ketogenic diet Archives - Health Tips From The Professor

The Low Carb Myth

April 8, 2025 by Dr. Steve Chaney

The “Goldilocks Effect”

Author: Dr. Stephen Chaney

The low carb wars rage on. Low carb enthusiasts claim that low-carb diets are healthy. And they claim the lower you go, the healthier you will be. Let me start with some definitions:

The typical American diet is high carb. It gets about 55% of its calories from carbohydrates. [Note: The Mediterranean and DASH diets also get about 55% of their calories from carbohydrates. I’ll talk more about that later.]

Moderate carb diets get 26-46% of their calories from carbohydrates. Examples include the low carb Mediterranean diet and the Paleo, South Beach, and Zone diets.

Low carb diets get <26% of their calories from carbohydrates. The Atkins diet is the classic example of a low carb diet.

Very low carb diets get <10% of their calories from carbohydrates. Examples are the Keto and Carnivore diets.

And I don’t need to tell you that the Keto and Carnivore diets are receiving a lot of favorable press lately.

But some health experts warn that low carb and very low carb diets may be dangerous. Several studies have reported that low carb diets increase the risk of mortality (shorten lifespan).

As a consumer you are probably confused by the conflicting claims. Are low carb diets healthy, or is this another myth? In this issue of “Health Tips From the Professor” I am going to discuss two very large studies that came to opposite conclusions.

Both were what we call meta-analysis studies. Simply put, that means they combine the data from several smaller studies to obtain more statistically reliable data. But as Mark Twain said, “There are lies. There are damn lies. And then there are statistics.”

The first study, called the Prospective Urban Rural Epidemiology (PURE) study, was published a few years ago. It included data from 135,335 participants from 18 countries across 5 continents. That’s a very large study, and normally we expect very large studies to be accurate.

It showed a linear relationship between carbohydrate intake and mortality. Simply put, the more carbohydrate people consumed, the greater their risk of premature death. The results from the PURE study had low carb enthusiasts doing a victory lap and claiming it was time to rewrite nutritional guidelines to favor low carb diets.

Whenever controversies like this arise, reputable scientists are motivated to take another look at the question. They understand that all studies have their weaknesses and biases. So, they look at previous studies very carefully and try to design a study that eliminates the weaknesses and biases of those studies. Their goal is to design a stronger study that reconciles the differences between the previous studies.

And this study had two glaring weaknesses.

The percent carbohydrate intake ranged from 40% to 80%. It showed that a moderate carbohydrate intake might be healthier than a high carbohydrate intake, but it provided no information about low carb or very low carb diets.

The data was primarily from Asian countries. It was not clear whether it was relevant to the kind of diets consumed in North America and Europe.

A second study published a year later (SB Seidelmann et al, The Lancet, doi.org/10.1016/S2468-2667(18)30135-X eliminated these weaknesses and resolved the conflicting data.

How Was The Second Study Done?

This study was performed in two parts. This first part drew on data from the Atherosclerosis Risk in Communities (ARIC) study. That study enrolled 15,428 men and women, aged 45-64, from four US communities between 1987 and 1989. This group was followed for an average of 25 years, during which time 6283 people died.

Carbohydrate intake was calculated based on food frequency questionnaires administered when participants enrolled in the study and again 6 years later. The study evaluated the association between carbohydrate intake and mortality.

The second part was a meta-analysis that combined the data from the ARIC study with all major clinical studies since 2007 that measured carbohydrate intake and mortality and lasted 5 years or more. The total number of participants included in this meta-analysis was 432,179, and it included data from previous studies that claimed low carbohydrate intake was associated with decreased mortality.

The Low Carb Myth

The results from the ARIC study were:

The relationship between mortality and carbohydrate intake was a U-shaped curve.

- The lowest risk of death was observed with a moderate carbohydrate intake (50-55%). This is the intake recommended by current nutrition guidelines.

- The highest risk of death was observed with a low carbohydrate intake (<20%).

- The risk of death also increased with very high carbohydrate intake (>70%).

When the investigators used the mortality data to estimate life expectancy, they predicted a 50-year-old participant would have a projected life expectancy of:

- 33.1 years if they had a moderate intake of carbohydrates.

- 4 years less if they had a very low carbohydrate intake.

- 1 year less if they had a very high carbohydrate intake.

The risk associated with low carbohydrate intake was affected by what the carbohydrate was replaced with.

- When carbohydrates were replaced with animal protein and animal fat there was an increased risk of mortality on a low-carb diet.

The animal-based low-carb diet contained more beef, pork, lamb, chicken, and fish. It was also higher in saturated fat.

- When carbohydrates were replaced with plant protein and plant fats, there was a decreased risk of mortality on a low-carb diet. The plant-based low-carb diet contained more nuts, peanut butter, dark or whole grain breads, chocolate, and white bread. It was also higher in polyunsaturated fats.

The effect of carbohydrate intake on mortality was virtually the same for all-cause mortality, cardiovascular mortality, and non-cardiovascular mortality.

There was no significant effect of carbohydrate intake on long-term weight gain (another myth busted).

The results from the dueling meta-analyses were actually very similar in some respects. When the data from all studies were combined:

Very high carbohydrate diets were associated with increased mortality.

Meat-based low-carb diets increased mortality, and plant-based low-carb diets decreased mortality.

The results were the same for total mortality, cardiovascular mortality, and non-cardiovascular mortality.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy and both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged.

Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

Simply put, that means if a low carb diet works best for you, it is healthier to replace the carbs with plant-based fats and protein rather than animal-based fats and protein.

The “Goldilocks Effect”

This study also resolved the discrepancies between previous studies. The authors pointed out that the PURE study relied heavily on data from Asian and developing countries, and the average carbohydrate intake is very different in Europe and the US than in Asian and developing countries.

In the US and Europe mean carbohydrate intake is about 50% of calories and it ranges from 25% to 70% of calories. With that range of carbohydrate intake, it is possible to observe the increase in mortality associated with both very low and very high carbohydrate intakes.

The US and European countries are affluent, which means that low carb enthusiasts can also afford diets high in animal protein.

In contrast, white rice is a staple in Asian countries, and protein is a garnish rather than a main course. Consequently, overall carbohydrate intake is greater in Asian countries and very few Asians eat a truly low carbohydrate diet.

High protein foods tend to be more expensive than high carbohydrate foods. Thus, very few people in developing countries can afford to follow a very low carbohydrate diet, and overall carbohydrate intake also tends to be higher in those countries.

Therefore, in Asian and developing countries the average carbohydrate intake is greater (~61%) than in the US and Europe (~50%), and the range of carbohydrate intake is from 45% to 80% of calories instead of 25% to 70%. With this range of intake, it is only possible to see the increase in mortality associated with very high carbohydrate intake.

In fact, when the authors of the current study overlaid the data from the PURE study with their ARIC data, there was an almost perfect fit. The only difference was that their ARIC data covered both low and high carbohydrate intake while the PURE study touted by low carb enthusiasts only covered moderate to high carbohydrate intake.

[I have given you my rendition of the graph on the right. If you would like to see the data yourself, look at the paper.]

Basically, low carb advocates are telling you that diets with carbohydrate intakes of 26% or less are healthy based on studies that did not include carbohydrate intakes below 40%. That is misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

In short, the ARIC study finally answered the question, “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough”.

I call this “The Goldilocks Effect”. You may remember “Goldilocks And The Three Bears”. One bed was too hard. One bed was too soft. But one bed was “just right”. One bowl of porridge was too hot. One was two cold. But one was “just right”.

According to this study, the same is true for carbohydrate intake. High carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But moderate carbohydrate intake is “just right”.

What Does This Study Mean For You?

There are several important take-home lessons from this study:

1) All major studies agree that very high carbohydrate intake is unhealthy. In part, that reflects the fact that diets with high carbohydrate intake are likely to be high in sodas and sugary junk foods. It may also reflect the fact that diets which are high in carbohydrates are often low in plant protein or healthy fats or both.

2) All studies that cover the full range of carbohydrate intake agree that low and very low carbohydrate diets are also unhealthy. They shorten the life expectancy of a 50-year-old by about 4 years.

3) The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets. Their claims are a myth.

4) Not all high carb diets are created equally. As I noted above, the Mediterranean and DASH diets are just as high in carbohydrates as the typical American diet, but their carbohydrates come from whole fruits and vegetables, whole grains, beans, nuts, and seeds. And multiple studies show that both diets are much healthier than the typical American diet.

5) Not all low carb diets are created equally. Meat-based low-carb diets decrease life expectancy compared to the typical American diets while plant-based low carb diets increase life expectancy.

6) The health risks of meat-based low-carb diets may be due to the saturated fat content or the heavy reliance on red meat. However, the risks are just as likely to be due to the foods these diets leave out – typically fruits, whole grains, legumes, and some vegetables.

7) Proponents of low-carb diets assume that you can make up for the missing nutrients by just taking multivitamins. However, each food group also provides a unique combination of phytonutrients and fibers. The fibers, in turn, influence your microbiome. Simply put, whenever you leave out whole food groups, you put your health at risk.

The Bottom Line

The low-carb wars are raging. Several studies have reported that low carb diets increase risk of mortality (shorten lifespan). However, a study published a few years ago came to the opposite conclusion. That study had low carb enthusiasts doing a victory lap and claiming it is time to rewrite nutritional guidelines to favor low-carb diets.

However, a study published a year later resolves the conflicting data and finally answers the question: “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough”.

I call this “The Goldilocks Effect”. According to this study, high carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But moderate carbohydrate intake is “just right”.

Specifically, this study reported:

Moderate carbohydrate intake (50-55%) is healthiest. This is the carbohydrate intake found in healthy diets like the Mediterranean and DASH diets, and is the intake recommended by current nutritional guidelines.

2) All major studies agree that very high carbohydrate intake (60-70%) is unhealthy. It shortens the life expectancy of a 50-year-old by about a year.

3) All studies that cover the full range of carbohydrate intake agree that low carbohydrate intake (<26%) is also unhealthy. It shortens the life expectancy of a 50-year-old by about 4 years.

4) The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

5) Meat-based low-carb diets decrease life expectancy compared to the typical American diet while plant-based low carb diets increase life expectancy. This is consistent with the results of previous studies.

Simply put, the latest study means that the supposed benefits of low carb diets are a myth.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

______________________________________________________________________________

My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

______________________________________________________________________

About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry textbooks for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 53 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Which Diets Are Heart Healthy?

September 26, 2023 by Dr. Steve Chaney

What Does A Heart Healthy Diet Look Like?

Author: Dr. Stephen Chaney

Heart disease is a big deal. According to the CDC, “Heart disease is the leading cause of death for men, women, and people of most racial and ethnic groups in the United States. One person dies every 33 seconds in the United States from cardiovascular disease. About 695,000 people in the United States died from heart disease in 2021 – that’s 1 in every 5 deaths”.

This doesn’t have to happen. According to the Cleveland Clinic, “90 percent of heart disease is preventable through healthier diet, regular exercise, and not smoking”. For this issue of “Health Tips From the Professor”, I will focus on the role of diet on heart health.

The problem is many Americans are confused. They don’t know what a heart-healthy diet is. There is so much conflicting information on the internet.

Fortunately, the American Heart Association has stepped in to clear up the confusion.

In 2021 they reviewed hundreds of clinical studies and published “Evidence-Based Dietary Guidance to Promote Cardiovascular Health”.

And recently they have published a comprehensive review (CD Gardner et al, Circulation, 147: 1715-1730, 2023) of how well popular diets align with their 2021 dietary guidelines.

I will cover both publications below. But first I want to address why Americans are so confused about which diets reduce heart disease risk.

Why Are Americans Confused About Diet And Heart Disease Risk?

I should start by addressing the “elephant in the room”.

As I discussed in last week’s “Health Tips From the Professor” article, Big Food Inc has seduced us. They have developed an unending supply of highly processed foods that are cheap, convenient, easy to prepare, and fulfill all our cravings. These foods are not heart-healthy, but they make up 73% of our food supply.

The Institute of Medicine, the scientific body that sets dietary standards, states that a wide range of macronutrient intakes are consistent with healthy diets. Specifically, they recommend carbohydrate intake at 45% to 65%, fat intake at 20% to 35%, and protein intake at 10% to 35% of total calories. (Of course, they are referring to healthy carbohydrates, fats, and proteins.)

The authors of this article pointed to several reasons why Americans have been misled about heart-healthy diets.

Many of the most popular diets fall outside of the “Acceptable Macronutrient Range”.

Many popular diets exclude heart-healthy food groups.

And, the words of the authors,

“Further contributing to consumer misunderstanding is the proliferation of diet books, [and] blogs [by] clinicians with limited understanding of what the dietary patterns entail and the evidence base for promoting cardiometabolic health.” I call these the Dr. Strangeloves of our world.

What Does A Heart Healthy Diet Look Like?

Let me start by sharing the American Heart Association’s 10 “Evidence-Based Dietary Guidelines to Promote Cardiovascular Health.

#1: Adjust energy intake and expenditure to achieve and maintain a healthy body weight
#2: Eat plenty of vegetables and fruits; choose a wide variety
#3: Choose foods made mostly with whole grains rather than refined grains
#4: Choose healthy sources of protein
	Mostly from plants (beans, other legumes, and nuts)
	Fish and seafood
	Low-fat or fat-free dairy products instead of full-fat dairy products
	If meat or poultry are desired, choose lean cuts and avoid processed forms
#5. Use liquid plant oils (olive, safflower, corn) rather than animal fats (butter and lard) and tropical oils (coconut and palm kernel)
#6. Use minimally processed foods instead of highly processed foods
#7: Minimize intake of beverages and foods with added sugars
#8: Choose and prepare foods with little or no salt
#9: If you do not drink alcohol, do not start; if you choose to drink alcohol, limit intake
#10: Adhere to this guidance regardless of where food is prepared or consumed

Here are my comments on these guidelines:

If you have been reading my “Health Tips From the Professor” blog for a while, you probably realize that these aren’t just guidelines to promote heart health. These guidelines also reduce the risk of diabetes, cancer, inflammatory diseases, and much more.

If you have read my post on coconut oil, you will know that I have a minor disagreement with the AHA recommendation to avoid it. There is no long-term evidence that coconut oil is bad for the heart. But there is also no long-term evidence that it is good for the heart. My recommendation is to use it sparingly.

And you probably know there has been considerable discussion recently about whether full fat dairy is actually bad for the heart. In my most recent review of the topic, I concluded that if full fat dairy is heart healthy, it is only in the context of a primarily plant-based diet and may only be true for fermented dairy foods like unpasteurized yogurt and kefir.

Finally, guideline 10 may need some translation. Basically, this guideline is just asking how easy it is to follow the diet when you are away from home.

Which Diets Are Heart Healthy?

In evaluating how well diets adhered to the American Heart Association guidelines the authors ignored item 1 (energy intake) because most of the diets they evaluated did not provide any guidelines on how many calories should be consumed.

Each diet was given a score between 0 (Fail) and 1 (A+) for each of the other 9 guidelines by a panel of experts. The points for all 9 guidelines were added up, giving each diet a rating of 0 (worst) to 9 (best). Finally, a score of 9 was assigned 100%, so each diet could be given a percentage score for adherence to heart-healthy guidelines.

Here are the results:

Tier 1 diets (the most heart healthy diets) received scores of 86% to 100%. Going from highest (100%) to lowest (86%), these diets were:

DASH, Nordic, Mediterranean, Pescetarian (vegetarian diets that allow fish), and Ovo-Lacto Vegetarian (vegetarian diets that allow dairy, eggs, or both).

You will notice that these are all primarily plant-based diets.

Tier 2 diets were Vegan and other low-fat diets (TLC, Volumetrics). They both received scores of 78%.

The Vegan diet received 0 points for category 10 (ease of following the diet when eating out). It was also downgraded in category 7 for not having clear guidance for the use of salt when preparing foods.

The other low-fat diets were downgraded in categories 7, 10, and 5 (use of tropical oils).

Tier 3 diets received scores of 64% to 72%. They included very-low fat diets (<10% fat, very strict vegan diets) and low-carb diets (Zone, South Beach, Low-Glycemic Index).

They received 0 points for category 10 and were downgraded for eliminating heart-healthy food groups (liquid plant oils for the very low-fat diets, and fruits, vegetables, whole grains, and plant proteins for the low-carb diets).

Tier 4 diets (the least heart healthy diets) were the Paleo diet with a score of 53% and very low-carb diets (Atkins and Ketogenic) with a score of 31%.

The Paleo diet received 0 points for categories 10, 3 (choose whole grains), and 5 (using liquid plant oils rather than animal fats or tropical oils). It was also downgraded for lack of healthy plant-based protein sources.

The very low-carb diets were the least heart healthy. They received 0 points for categories 2 (eat plenty of fruits and vegetables), 3 (choose whole grains), 3 (healthy protein sources), 5 (use liquid plant oils instead of animal fats), 7 (minimize salt consumption), and 10 (ease of following the diet away from home).

The authors concluded, “Numerous [dietary] patterns [are] strongly aligned with 2021 American Heart Association Dietary Guidance (ie, Mediterranean, DASH, pescetarian, vegetarian) [and] can be adopted to reflect personal and cultural preferences and budgetary constraints.

Thus, optimal cardiovascular health would be best supported by developing a food environment that supports adherence to these patterns wherever food is prepared or consumed.”

Given our current food environment that last statement is wildly optimistic. But at least you have the information needed to make the best food choices for you and your family

The Bottom Line

In 2021 the American Heart Association published 10 guidelines for evaluating heart-healthy diets. A recent study looked at how well popular diets adhered to those guidelines. The authors separated the diets into four categories (tiers) based on how heart-healthy they were. The results were not surprising:

Tier 1 diets (the most heart healthy diets) were DASH, Nordic, Mediterranean, Pescetarian (vegetarian diets that allow fish), and Ovo-Lacto Vegetarian (vegetarian diets that allow dairy, eggs, or both).

Tier 2 diets were Vegan and other low-fat diets (TLC, Volumetrics).

Tier 3 diets included very-low fat diets (<10% fat, very strict vegan diets) and low-carb diets (Zone, South Beach, Low-Glycemic Index).

Tier 4 diets (the least heart healthy diets) were the Paleo diet and very low-carb diets (Atkins and Ketogenic).

Thus, optimal cardiovascular health would be best supported by developing a food environment that supports adherence to these patterns wherever food is prepared or consumed.”

Given our current food environment that last statement is wildly optimistic. But at least you have the information needed to make the best food choices for you and your family.

For more information on this study, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

____________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

Which Diets Are Best In 2023?

February 14, 2023 by Dr. Steve Chaney

Which Diet Should You Choose?

Author: Dr. Stephen Chaney

Many of you started 2023 with goals of losing weight and/or improving your health. In many cases, that involved choosing a new diet. That was only 6 weeks ago, but it probably feels like an eternity.

For many of you the “bloom” has gone off the new diet you started so enthusiastically in January.

Perhaps the diet isn’t working as well as advertised…

Perhaps the diet is too restrictive. You are finding it hard to stick with…

Perhaps you are always hungry or constantly fighting food cravings…

Perhaps you are starting to wonder whether there is a better diet than the one you chose in January…

Perhaps you are wondering whether the diet you chose is the wrong one for you…

If you are rethinking your diet, you might want to know which diets the experts recommend. Unfortunately, that’s not as easy as it sounds. The diet world has become just as divided as the political world.

Fortunately, you have an impartial resource. Each year US News & World Report invites a panel of experts with different points of view to evaluate popular diets. They then combine the input from all the experts into rankings of the diets in various categories.

If you are still searching for your ideal diet, I will summarize the US News & World Report’s “Best Diets In 2023”. For the full report, click on this link.

How Was This Report Created?

US News & World Report recruited a panel of 30 nationally recognized experts in diet, nutrition, obesity, food psychology, diabetes, and heart disease to review the 24 most popular diets.

The diets evaluated are not the same each year. Last year they evaluated the top 40 most popular diets. This year they only reviewed the top 24.

That means some good diets were left off the list. For example, the vegan diet is very healthy, but it is also very restrictive. Very few people follow a pure vegan diet, so it didn’t make the top 24 most popular. However, this year’s list did include several primarily plant-based diets that are more popular with the general public.

The panel is also not the same each year. Some experts are rotated off the panel, and others are added. The experts rate each diet in seven categories:

How easy it is to follow.

Its ability to produce short-term weight loss.

Its ability to produce long-term weight loss.

its nutritional completeness.

Its safety.

Its potential for preventing and managing diabetes.

Its potential for preventing and managing heart disease.

They converted the experts’ ratings to scores 5 (highest) to 1 (lowest). They then used these scores to construct eleven sets of Best Diets rankings:

Best Diets Overall ranks diets on several different parameters, including whether all food groups are included in the diet, the availability of the foods needed to be on the diet and the use of additional vitamins or supplements. They considered if the diet was evidence-based and adaptable to meet cultural, religious, or other personal preferences. In addition, the criteria also included evaluation of the prep and planning time required for the diet and the effectiveness of the diet for someone who wants to get and stay healthy.

Best Plant-Based Diets used the same approach as Best Diets Overall to rank the eight plans emphasizing minimally processed foods from plants that were included in this year’s ratings.

Best Commercial Diet ratings used the same approach to rank 15 commercial diet programs that require a participation fee or promote the use of branded food or nutritional products.

Best Long-Term Weight-Loss Diet ratings were generated by combining the safety of the rate of weight loss promoted and the likelihood of the plan to result in successful long-term weight loss and maintenance of weight loss.

Best Fast Weight-Loss Diets were scored on their effectiveness for someone who wants to lose weight in three months or less.

Best Diabetes Diet ratings were calculated equally from the effectiveness of the diet for someone who wants to lower risk factors for diabetes, the nutritional quality of the diet, and research evidence-based support for the diet.

Best Heart-Healthy Diet ratings were calculated equally from the effectiveness of the diet for someone who wants to lower risk factors for hypertension and other forms of heart disease, the nutritional quality of the diet, and evidence-based support for the diet.

Best Diets for Bone and Joint Health were calculated equally on the effectiveness of the diet for someone who wants to lower their risk factors for inflammation and improve bone and joint health, as well as the nutritional quality and research evidence-based support for the diet.

Best Diets for Healthy Eating combines nutritional completeness and safety ratings, giving twice the weight to safety. A healthy diet should provide sufficient calories and not fall seriously short on important nutrients or entire food groups.

Easiest Diets to Follow represents panelists’ averaged scores for the relevant lifestyle questions, including whether all food groups are included and if the recommended foods are readily available at the average supermarket.

Best Family-Friendly Diets were calculated equally on their adaptability for the whole family, including cultural, religious, and personal preferences, the time required to plan and prep, nutritional value and access to food at any supermarket.

Which Diets Are Best In 2023?

Are you ready? If this were an awards program, I would be saying “Envelop please” and would open the envelop slowly to build suspense.

However, I am not going to do that. Here are the top 3 and bottom 3 diets in each category (If you would like to see where your favorite diet ranked, click on this link.

[Note: I excluded commercial diets from this review. (I have a brief discussion of commercial diets below). If you notice a number missing in my summaries, it is because I eliminated one or more commercial diet from my summary.]

Best Diets Overall

The Top 3:

#1: Mediterranean Diet. The Mediterranean diet has been ranked #1 for 6 consecutive years.

#2 (tie): DASH Diet (This diet was designed to keep blood pressure under control, but you can also think of it as an Americanized version of the Mediterranean diet.)

#2 (tie): Flexitarian Diet (A flexible semi-vegetarian diet).

The Bottom 3:

#20: Keto Diet (A high protein, high fat, very low carb diet designed to achieve ketosis).

#21: Atkins Diet (The granddaddy of the high animal protein, low carb, high fat diets).

#24: Raw Food Diet (A diet based on eating foods that have not been cooked or processed).

Best Plant-Based Diets Overall

The Top 3:

#1: Mediterranean Diet.

#2: Flexitarian Diet.

#3: MIND Diet (This diet is a combination of Mediterranean and DASH but is specifically designed to reduce cognitive decline as we age.)

The Bottom 3:

Since only 8 diets were included in this category, even the bottom 3 are pretty good diets, so I did not include a “list of shame” in this category.

Best Long-Term Weight-Loss Diets

The Top 3:

#1: DASH Diet

#2 (tie): Volumetrics Diet (A diet based on the caloric density of foods).

#2 (tie): Mayo Clinic Diet (A diet designed to establish lifelong healthy eating habits).

The Bottom 3:

#22 (tie): Keto Diet.

#22 (tie): Atkins Diet.

#24: Raw Food Diet.

Best Fast Weight-Loss Diets

The Top 3:

#1: Keto Diet

#2: Atkins Diet

#7 (tie): Mayo Clinic Diet

#7 (tie): South Beach Diet

#7 (tie): Volumetrics Diet

The Bottom 3:

The diets at the bottom of this list were designed for health and weight maintenance rather than rapid weight loss, so I did not include a “list of shame” in this category.

Best Diabetes Diets

The Top 3:

#1: DASH Diet

#2: Mediterranean Diet

#3: Flexitarian Diet

The Bottom 3:

#20: Atkins Diet

#21: Paleo Diet (A diet based on what our paleolithic ancestors presumably ate. It restricts grains and dairy and is heavily meat-based).

#22: Raw Food Diet.

Best Heart-Healthy Diets

The Top 3:

#1: DASH Diet

#2: Mediterranean Diet

#3 (tie): Ornish Diet (A whole food, semi-vegetarian diet designed to promote heart health).

#3 (tie): Flexitarian Diet

The Bottom 3:

#22 (tie): Raw Foods Diet

#22 (tie): Paleo Diet

#24: Keto Diet

Best Diets for Bone and Joint Health

The Top 3:

#1 (tie): DASH Diet

#1 (tie): Mediterranean Diet

#3: Flexitarian Diet

The Bottom 3:

#21 (tie): Raw Foods Diet

#21 (tie): Paleo Diet

#22: Atkins Diet

#23: Keto Diet

Best Diets for Healthy Eating

The Top 3:

#1: Mediterranean Diet

#2: DASH Diet

#3: Flexitarian Diet

The Bottom 3:

#22: Keto Diet

#23: Atkins Diet

#24: Raw Foods Diet

Easiest Diets to Follow

The Top 3:

#1 (tie): Flexitarian Diet

#1 (tie): TLC Diet (This diet was designed by the NIH to reduce cholesterol levels and promote heart health.)

#3 (tie): Mediterranean Diet

#3 (tie): DASH Diet

The Bottom 3:

#19: Atkins Diet

#20: Keto Diet

#22: Raw Foods Diet

Which Diets Are Best For Rapid Weight Loss?

There are 2 take-home lessons from the rapid weight loss category:

If you are looking for rapid weight loss, any whole food restrictive diet will do.

- Last year’s diet analysis included the vegan diet, and both vegan and keto diets ranked near the top of the rapid weight loss category. Keto and vegan diets are both very restrictive, but they are polar opposites in terms of the foods they allow and restrict.

- - The keto diet is a meat heavy, very low carb diet. It restricts fruits, some vegetables, grains, and most legumes.

- - The vegan diet is a very low-fat diet that eliminates meat, dairy, eggs, and animal fats.

- The Atkins and keto diets toppled this year’s rapid weight loss list, but they were joined by the Mayo Clinic, South Beach, and volumetrics diets. Those diets are also restrictive, but, like the vegan diet, they are very different from the Atkins and keto diets.

- I did not include commercial diets that rated high on this list, but they are all restrictive in one way or another.

2) Whole food, very low carb diets like Atkins and keto are good for rapid weight loss, but they rank near the bottom of the list for every healthy diet category.

- If you choose to lose weight on the Atkins or keto diets, switch to a healthier diet once you reach your desired weight loss.

Which Diet Should You Choose?

With rapid weight loss out of the way, let’s get back to the question, “Which Diet Should You Choose?” My recommendations are:

1) Choose a diet that fits your needs. That is one of the things I like best about the US News & World Report ratings. The diets are categorized. If your main concern is diabetes, choose one of the top diets in that category. If your main concern is heart health… You get the point.

2) Choose diets that are healthy and associated with long term weight loss. If that is your goal, you will notice that primarily plant-based diets top these lists. Meat-based, low carb diets like Atkins and keto are near the bottom of the lists.

“Why is that?”, you might ask? The answer is simple. And it’s not that all 30 experts were prejudiced against low carb diets. It’s that the major primarily plant-based diets like Mediterranean, DASH, and flexitarian are backed by long-term clinical studies showing they are healthy and significantly reduce the risk of diabetes, heart disease, and other chronic diseases.

On the other hand, there are no long-term studies showing the Atkins and keto diets are healthy long term. And since the Atkins diet has been around for more than 50 years, the lack of clinical evidence that it is healthy long term is damming.

3) Choose diets that are easy to follow. The less-restrictive primarily plant-based diets top this list – diets like Mediterranean, DASH, MIND, and flexitarian. They are also at or near the top of almost every diet category.

4) Choose diets that fit your lifestyle and dietary preferences. For example, if you don’t like fish and olive oil, you will probably do much better with the DASH or flexitarian diet than with the Mediterranean diet.

5) Finally, focus on what you have to gain, rather than on foods you have to give up.

On the minus side, none of the diets include sodas, junk foods, and highly processed foods. These foods should go on your “No-No” list. Sweets should be occasional treats and only as part of a healthy meal. Meat, especially red meat, should become a garnish rather than a main course.

On the plus side, primarily plant-based diets offer a cornucopia of delicious plant foods you probably didn’t even know existed. Plus, for any of the top-rated plant-based diets, there are websites and books full of mouth-watering recipes. Be adventurous.

What About Commercial Diets?

I chose not to review commercial diets by name, but let me make a few observations.

If you look at the gaps in my lists, it should be apparent that several commercial diets rank near the top for fast weight loss, but near the bottom on most healthy diet lists.

I do not recommend commercial diets that rely on ready-to-eat, low-calorie, highly processed versions “of your favorite foods”.

- These pre-packaged meals are expensive. Unless you are a millionaire, you won’t be able to afford these meals for the rest of your life.

- These pre-packaged meals are not teaching you healthy eating habits that will allow you to keep the weight off.

If you wish to spend your hard-earned dollars on a commercial diet, choose a diet that:

- Relies on whole foods from all 5 food groups.

- Teaches and provides support for the type of lifestyle change that leads to permanent weight loss.

Meal replacement shakes can play a role in healthy weight loss if:

- They are high quality and use natural ingredients as much as possible.

- They are part of a holistic lifestyle change program.

The Bottom Line

For many of you the “bloom” has gone off the new diet you started so enthusiastically in January. If you are rethinking your diet, you might want to know which diets the experts recommend. Unfortunately, that’s not as easy as it sounds. The diet world has become just as divided as the political world.

There are probably two questions at the top of your list.

#1: Which diets are best for rapid weight loss? Here are 2 general principles:

If you are looking for rapid weight loss, any whole food restrictive diet will do.

2) If you choose to lose weight on the Atkins or keto diets, switch to a healthier diet once you reach your desired weight loss. Atkins and keto diets are good for rapid weight loss, but they rank near the bottom of the list for every healthy diet category.

#2: Which diet should you choose? Here the principles are:

Choose a diet that fits your needs.

2) Choose diets that are healthy and associated with long term weight loss.

3) Choose diets that are easy to follow.

4) Choose diets that fit your lifestyle and dietary preferences.

5) Finally, focus on what you have to gain, rather than on foods you have to give up.

For more details on the diet that is best for you and my thoughts on commercial diets, read the article above.

Which Diets Are Best In 2022?

February 8, 2022 by Dr. Steve Chaney

Which Diet Should You Choose?

Author: Dr. Stephen Chaney

Many of you started 2022 with goals of losing weight and/or improving your health. In many cases, that involved choosing a new diet. That was only a month ago, but it probably feels like an eternity.

For many of you the “bloom” has gone off the new diet you started so enthusiastically in January.

Perhaps the diet isn’t working as well as advertised…

Perhaps the diet is too restrictive. You are finding it hard to stick with…

Perhaps you are always hungry or constantly fighting food cravings…

Perhaps you are starting to wonder whether there is a better diet than the one you chose in January…

Perhaps you are wondering whether the diet you chose is the wrong one for you…

If you are still searching for your ideal diet, I will summarize the US News & World Report’s “Best Diets In 2022”. For the full report, click on this link.

How Was This Report Created?

US News & World Report recruited panel of 27 nationally recognized experts in diet, nutrition, obesity, food psychology, diabetes, and heart disease to review the 40 most popular diets. The panel is not the same each year. Some experts are rotated off the panel, and others are added. The experts rate each diet in seven categories:

How easy it is to follow.

Its ability to produce short-term weight loss.

Its ability to produce long-term weight loss.

its nutritional completeness.

Its safety.

Its potential for preventing and managing diabetes.

Its potential for preventing and managing heart disease.

They converted the experts’ ratings to scores 5 (highest) to 1 (lowest). They then used these scores to construct nine sets of Best Diets rankings:

Best Diets Overall combines panelists’ ratings in all seven categories. However, all categories were not equally weighted. Short-term and long-term weight loss were combined, with long-term ratings getting twice the weight. Why? A diet’s true test is whether it can be sustained for years. And safety was double counted because no diet should be dangerous.

Best Commercial Diets uses the same approach to rank 15 structured diet programs that require a participation fee or promote the use of branded food or nutritional products.

Best Weight-Loss Diets was generated by combining short-term and long-term weight-loss ratings, weighting both equally. Some dieters want to drop pounds fast, while others, looking years ahead, are aiming for slow and steady. Equal weighting accepts both goals as worthy.

Best Diabetes Diets is based on averaged diabetes ratings.

Best Heart-Healthy Diets uses averaged heart-health ratings.

Best Diets for Healthy Eating combines nutritional completeness and safety ratings, giving twice the weight to safety. A healthy diet should provide sufficient calories and not fall seriously short on important nutrients or entire food groups.

Easiest Diets to Follow represents panelists’ averaged judgments about each diet’s taste appeal, ease of initial adjustment, ability to keep dieters from feeling hungry and imposition of special requirements.

Best Plant-Based Diets uses the same approach as Best Diets Overall to rank 12 plans that emphasize minimally processed foods from plants.

Best Fast Weight-Loss Diets is based on short-term weight-loss ratings.

Which Diets Are Best In 2022?

Are you ready? If this were an awards program I would be saying “Envelop please” and would open the envelop slowly to build suspense.

However, I am not going to do that. Here are the top 5 and bottom 5 diets in each category (If you would like to see where your favorite diet ranked, click on this link). [Note: I excluded commercial diets from this review.]

Best Diets Overall

The Top 5:

#1: Mediterranean Diet. The Mediterranean diet has been ranked #1 for 5 consecutive years.

#2: DASH Diet (This diet was designed to keep blood pressure under control, but you can also think of it as an Americanized version of the Mediterranean diet.)

#3: Flexitarian Diet (A flexible semi-vegetarian diet).

#4: MIND Diet (This diet is a combination of Mediterranean and DASH but is specifically designed to reduce cognitive decline as we age.)

#5: The TLC Diet (This diet was designed by the NIH to promote heart health.)

The Bottom 5:

#36: Whole 30 Diet (A whole food, restrictive diet, designed for a 30-day jump start to weight loss. It was not designed for long-term use).

#37: Modified Keto Diet (A slightly less restrictive version of the Keto Diet).

#38: Keto Diet (A high protein, high fat, very low carb diet designed to achieve ketosis).

#39: Dukan Diet (High protein, low carb, low fat diet).

#40: GAPS Diet (A diet designed to improve gut health).

Best Weight-Loss Diets

The Top 5:

#1: Flexitarian Diet

#2: Volumetrics Diet (A diet based on the caloric density of foods).

#3: Vegan Diet (A diet that only allows plant foods).

#4: Mayo Clinic Diet (A diet designed to establish lifelong healthy eating habits).

#5: Ornish Diet (A whole food, semi-vegetarian diet designed to promote heart health).

The Bottom 5:

#36: Fertility Diet (A diet designed to improve fertility, but the experts were skeptical that it would increase your chances of becoming pregnant)

#37: Whole 30 Diet

#38: Alkaline Diet (A diet designed to make your blood more alkaline, but the experts were skeptical about that claim)

#39: AIP Diet (A diet designed for people with autoimmune diseases)

#40: GAPS Diet

Best Diabetes Diets

The Top 5:

#1: Mediterranean Diet

#2: Flexitarian Diet

#3: Vegan Diet

#4: Mayo Clinic Diet

#5: DASH Diet

The Bottom 5:

#36: Alkaline Diet

#37: Dukan Diet

#38: GAPS Diet

#39: Sirtfood Diet (a very low calorie, fad diet that emphasizes plant foods rich in sirtuins)

#40: Whole 30 Diet

Best Heart-Healthy Diets

The Top 5:

#1: Mediterranean Diet

#2: Ornish Diet

#3: DASH Diet

#4: Flexitarian Diet

#5: TLC Diet

#6: Vegan Diet

The Bottom 5:

#36: Keto Diet

#37: AIP Diet

#38: Whole 30 Diet

#39: Modified Keto Diet

#40: Dukan Diet

Best Diets for Healthy Eating

The Top 5:

#1: Mediterranean Diet

#2: DASH Diet

#3: Flexitarian Diet

#4: MIND Diet

#5: TLC Diet

The Bottom 5:

#36: Raw Food Diet

#37: Atkins Diet

#38: Dukan Diet

#39: Modified Keto Diet

#40: Keto Diet

Easiest Diets to Follow

The Top 5:

#1: Mediterranean Diet

#2: Flexitarian Diet

#3: Fertility Diet

#4: MIND Diet

#5: DASH Diet

The Bottom 5:

#36: Modified Keto Diet

#37: Keto Diet

#38: Whole 30 Diet

#39: GAPS Diet

#40: Raw Foods Diet

Best Fast Weight-Loss Diets

The Top 5 (Excluding Commercial Diets):

#1: Atkins Diet

#2: Biggest Loser Diet

#3: Keto Diet

#4: Raw Food Diet

#5: Vegan Diet

The Bottom 5

#36: Dr. Weil’s Anti-Inflammatory Diet

#37: The Fertility Diet

#38: AIP Diet

#39: Alkaline Diet

#40: Gaps Diet

Which Diets Are Best For Rapid Weight Loss?

There are 3 take-home lessons from the rapid weight loss category:

1) If you are looking for rapid weight loss, any whole food restrictive diet will do. The top 5 diets are very different. For example, the keto and vegan diets are polar opposites, yet they both are in the top 5 for rapid weight loss.

The Atkins and keto diets are meat heavy, low carb diets. They restrict fruits, some vegetables, grains, and most legumes.

The Biggest Loser diet relies on restrictive meal plan and exercise programs.

The restrictions of the raw food diet are obvious.

The vegan diet is a very low-fat diet that eliminates meat, dairy, eggs, and animal fats.

I did not include commercial diets that rated high on this list, but they are all restrictive in one way or another.

2) We should ask what happens when we get tired of restrictive diets and add back some of your favorite foods.

If you lose weight on a vegan diet and add back some of your favorite foods, you might end up with a semi-vegetarian diet. This is a healthy diet that can help you maintain your weight loss.

If you lose weight on the Atkins or keto diets and add back some of your favorite foods, you end up with the typical American diet – one that is high in both fat and carbs. This is not a recipe for long-term success.

3) Don’t pay too much attention to the bottom 5 diets. None of them were designed with weight loss in mind.

Which Diet Should You Choose?

With rapid weight loss out of the way, let’s get back to the question, “Which Diet Should You Choose?” My recommendations are:

3) Choose diets that are easy to follow. The less-restrictive primarily plant-based diets top this list – diets like Mediterranean, DASH, MIND, and flexitarian.

5) In case you were wondering, intermittent fasting ranked 26-30 and the Paleo diet ranked 26-33 on most of the list – not the worst diets, but a long way from the best. If you have a favorite diet I didn’t mention, check the US News website to find where it is ranked.

6) Finally, focus on what you have to gain, rather than on foods you have to give up.

On the minus side, none of the diets include sodas, junk foods, and highly processed foods. These foods should go on your “No-No” list. Sweets should be occasional treats and only as part of a healthy meal. Meat, especially red meat, should become a garnish rather than a main course.

On the plus side, primarily plant-based diets offer a cornucopia of delicious plant foods you probably didn’t even know existed. Plus, for any of the top-rated plant-based diets, there are websites and books full of mouth-watering recipes. Be adventurous.

The Bottom Line

There are probably two questions at the top of your list.

#1: Which diets are best for rapid weight loss? Here are some general principles:

If you are looking for rapid weight loss, any whole food restrictive diet will do.

We should ask what happens when we get tired of restrictive diets and add back some of our favorite foods.

Long term weight loss is possible if you transition to a healthy diet after you have lost the weight.

#2: Which diet should you choose? Here the principles are:

Choose a diet that fits your needs.

Choose diets that are healthy and associated with long term weight loss.

Choose diets that are easy to follow.

Choose diets that fit your lifestyle and dietary preferences.

Finally, focus on what you have to gain, rather than on foods you have to give up.

For more details on the diet that is best for you, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Is The Keto Diet Best For Endurance Exercise?

October 27, 2020 by Dr. Steve Chaney

Where Do Food Myths Come From?

I don’t need to tell you that the keto diet is popular right now. It is touted for weight loss, mental sharpness, and improved health. I discuss the accuracy of those claims in my book, “Slaying the Food Myths”.

Perhaps more surprising has been the adoption of the keto diet by so many endurance athletes. As I point out in my book, there is a kernel of truth for that idea. Fats and ketone bodies are a very efficient energy source for low to moderate intensity exercise, and we have a virtually unlimited source of stored fat that can be converted to ketone bodies.

However, I always add this caveat, “The keto diet is perfect for endurance exercise – as long as you don’t care how fast you get there”. That is because high intensity exercise requires muscle glycogen stores, which come from the carbohydrates we eat. When you cut carbs from the diet, you deplete your glycogen stores.

And, if you are running a marathon and you want to sprint to the finish line, you will need those muscle glycogen stores. Or, if you are in a cycling event and you want to power up a mountain, you will need those glycogen stores.

Of course, you are probably asking, “Why do so many endurance athletes swear by the keto diet?” There is a dirty little secret behind athlete endorsements. I’m not talking about the money that top athletes get paid for endorsements, although that is also a problem.

I’m talking about the testimonials you hear from your friend who runs marathons or your personal trainer. Unfortunately, testimonials from athletes are notoriously unreliable. The problem is that the placebo effect approaches 70% for athletes.

Competitive athletes are strong willed. If they think a diet or sports nutrition product will help them, they will themselves to a higher level of performance. And this happens subconsciously. They aren’t even aware that their mind is influencing their performance.

So, just because your favorite athlete endorses the keto diet doesn’t mean it is the perfect diet for you. Testimonials can be very misleading.

The important question to ask is, “Do clinical studies support the keto diet as the best diet for endurance exercise?” But, before I answer that question, let me frame the question by asking. “Where do food myths come from?” because the belief that keto diets are best for endurance exercise is a classic food myth.

Where Do Food Myths Come From?

I discussed this question at length in my book, “Slaying The Food Myths”. Let me summarize it briefly here.

Secrets Only Scientists Know: First you need to know the secrets only scientists know. Here are the top 2:

#1: Scientists design their studies to disprove previous studies. There is no glory for being the 10^th person to confirm the existing paradigm. The glory comes from being the first to show the existing paradigm might be wrong. While this may seem to be a contrary approach, it is actually the strength of the scientific method.

However, it means that there will be published clinical studies on both sides of every issue.

#2: Every study has its flaws. There is no perfect study.

This is why the scientific community doesn’t base their recommendations on 2 or 3 published studies. We wait until there are 10 to 20 good quality studies and base our recommendations on what 90% of them show.

Now, let me contrast the scientific approach with how food myths are born.

Where Do Food Myths Come From? Food myths usually originate on blogs or websites. Often the articles are written by people with no scientific credentials. But some of them are written by doctors (I will call them Dr. Strangelove to “protect the guilty”). The articles they write have these things in common:

The articles are based on the biases of the author. No effort is made to look at the other side of the story.

The authors “cherry pick” studies that support their bias and ignore studies that contradict them.

They use scientific-sounding mumbo jumbo to make their hypothesis sound credible.

Their articles are usually spectacular. For example, they say things like, “A particular diet, food, or supplement will either cure you or kill you”, and/or “The medical community is hiding the truth from you.”

They never let the facts get in the way of a good story.

Since the idea sounds credible it is picked up by other blogs and websites without any fact checking (social media at its worst). Once it has been repeated often enough, it becomes generally accepted as true. It becomes a food myth. From that point on, studies that disprove the myth are often ignored.

How do you know whether a common belief is true, or just another myth? The only way to be sure is to take a balanced look at all the clinical studies, not just the studies that support the belief.

That is what the authors of a recent review paper (CP Bailey and E Hennessy, Journal of the international Society of Sports Nutrition, 17, Article number: 33, 2020) did for the belief that the keto diet is the best diet for endurance exercise.

Is The Keto Diet Best For Endurance Exercise?

Before I discuss the findings of the review article, there are two things you should know:

#1: There is little scientific research on the effectiveness of the keto diet on endurance exercise. After an exhaustive search of the literature, the authors were only able to find 7 published studies on the topic.

#2:Most sports nutrition studies are of poor quality. In general, they are very small studies, are of short duration, and do not use common test procedures to measure a successful outcome. These studies on keto diets were no different. For example:

- The number of subjects in these studies ranged from 5 to 29 (average = 14).

- The duration of time on the diet in these studies ranged from 3 weeks to 12 weeks (average = 5 weeks).

- Tests used to measure the effectiveness of specific diets on endurance exercise were VO2max (the maximum amount of oxygen you can utilize during exercise), Time to exhaustion (how long you can exercise before you are exhausted), Rating of perceived exertion (feeling of fatigue at the end of the exercise), Race time (time required to complete an event), and Peak power output during the event.

- Four studies used a treadmill to simulate endurance exercise. The other three used a stationary bike.

- Five of the studies compared the keto diet to a high carbohydrate diet. Two studies used the keto diet only.

The results were all over the place:

Two studies reported an increase in VO2max for both the keto diet and the high carbohydrate diet. One study reported a decrease in VO2max for both diets. The other studies reported no change in VO2max. In short, there was no difference between the diets for VO2max.

One study reported a decrease in race time for the high carbohydrate diet and a non-significant increase in race time for the keto diet. Two other studies reported no effect of either diet on race time. In short, one study suggested the high carbohydrate diet was more effective at shortening race time. The other two studies found no effect of either diet.

Two studies showed an increase in time to exhaustion for both diets. One study showed a decrease in time to exhaustion for the keto diet (participants got tired more quickly). That study did not include the high carbohydrate diet for comparison. In short, there was no clear difference between the two diets for time to exhaustion.

One study showed that the group on the keto diet reported a higher rating of perceived exertion (were more tired) at the end of the endurance event than the group on the high carbohydrate diet. Another study found no difference between the two diets. In short, one study suggested the high carbohydrate diet was better with respect to perceived exertion (tiredness) at the end of the endurance event. Another study found no difference between the two diets.

One study reported that peak power was significantly greater for the group on the keto diet than the group on the high carbohydrate diet. One of the studies with the keto group reported that peak power decreased for 4 out of 5 subjects on the keto diet. In short, one study suggested that the keto diet was more effective at increasing peak power than the high carbohydrate diet. Another study suggested the keto diet decreased peak power.

The authors concluded: “When compared to a high carbohydrate diet, there are mixed findings for the effect of the keto diet on endurance performance…The limited number of published studies point to a need for more research in this field.” I would add that we need larger, better designed studies, with common measures of exercise performance.

What Does This Mean For You?

You may be wondering why I even bothered to talk about such poor-quality studies and a review that could not provide a definitive answer. In fact, that is exactly my point.

This is characteristic of the kind of “evidence” that Dr. Strangelove and his buddies present to support whatever food myth they are featuring on their website. They don’t know how to distinguish good studies from bad studies, and they “cherry pick” only the studies that support their food myth.

So, if you believe that the keto diet is best for endurance exercise, you can “cherry pick” the one published clinical study that supports your belief. You just need to ignore the other 6 published studies.

And, if you believe that a high carbohydrate diet is better for endurance exercise than the keto diet, you can “cherry pick” two clinical studies that support your belief. You just need to ignore the other 5 published clinical studies.

None of the studies are high-quality studies, and the effect of either diet on endurance exercise in these studies is miniscule.

In short, there is no convincing evidence that the keto diet is best for endurance exercise. Or, put another way, we do not have enough evidence to elevate that belief from a food myth to a recommendation we can confidently make for an endurance athlete.

The Bottom Line

A recent publication conducted an impartial review of the evidence for and against the popular belief that a keto diet is the best diet for endurance exercise. The review found only 7 poor-quality studies on this topic in the scientific literature, and the results of those studies were all over the map.

One study reported the keto diet was better than a high carbohydrate diet for endurance exercise.

Two studies reported that the high carbohydrate diet was better.

The other 4 studies were inconclusive.

None of the studies found a significant effect on endurance performance by either diet.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.