fatty liver

Is Fast Food Fat Food?

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Fat Metabolism Simplified 

Author: Dr. Stephen Chaney 

If you are like most Americans, you have vowed to lose weight and/or gain health in 2023. But how do you do that? There are hundreds of diets to choose from. And each diet has its “story” – a mixture of pseudo-science and testimonials – designed to convince you to try it.

Forget the pseudo-science. Forget the testimonials. Instead, focus on the one thing these diets have in common. They are all whole food diets. They all eliminate sodas, fast foods, and highly processed convenience foods.

In fact, that may be the simplest thing you can do to lose weight and become healthier. Many experts say that any time you eliminate sodas, fast foods, and convenience foods you will lose weight. If that statement is true, it could explain the American obesity epidemic. Between 1977 and 2017, a span of just 40 years, fast food consumption:

  • Increased from 6% to 35% (a 6-fold increase) in the 40-65 age group, and…
  • 11% to 46% (a 4-fold increase) in the 12-39 age group.

But is it true? There are certainly reasons to think it might be:

  • Fast foods are high in fat, sugar, and calories and are low in fiber – all of which are associated with obesity.
  • Big Food Inc has researched the ideal combination of taste, mouth feel, and effect on blood sugar to create an addiction to fast food.

However, the studies linking fast food consumption to obesity have been flawed.

  • People who consume fast foods tend to exercise less and have a poorer diet, even when they are eating at home. Previous studies have not distinguished between fast food consumption and other things (diet, exercise, lifestyle) that are also linked to obesity.
  • Previous studies have often only assessed diet and other lifestyle factors at the beginning or end of the study. There is no way of knowing whether these values are typical for the entire timespan of the study.
  • Previous studies have only shown associations, not cause and effect.

The current study (AO Odegaard et al, American Journal of Clinical Nutrition, 116: 255-262, 2022) was designed to eliminate many of the flaws in previous studies.

Fat Metabolism Simplified

You have probably heard that belly fat increases your risk of diabetes, heart disease, stroke, Alzheimer’s, and some cancers. This study looked at the effect of fast foods on belly fat, muscle fat, and fatty liver (liver fat).

However, belly fat is both simple and complicated:

  • It is simple in that it is easy to see. We talk about it as an “apple shape” and we measure it in waste circumference.
  • It is complicated because, anatomically, there are several subtypes of belly fat, and these authors chose to examine the effect of fast foods on each subtype.
  • However, the effect of fast foods on each subtype of belly fat, and the metabolic effects of each subtype, are similar. So, in the interest of simplicity, I will combine the subtypes and simply refer to the effect of fast foods on belly fat.

With that in mind, here is all you need to know about biology and metabolism of fat.

In addition to fat accumulation in the abdomen (belly fat), this study also looked fat accumulation in muscle (which I will refer to as muscle fat) and liver (which I will refer to as liver fat).

All three types of fat contribute to metabolic syndrome (prediabetes) characterized by:

  • Insulin resistance, which leads to an elevation of both glucose and insulin.
  • High LDL (bad cholesterol) and low HDL (good cholesterol).
  • High triglycerides.
  • High blood pressure.
  • Inflammation

These metabolic effects increase the risk of diabetes, heart disease, stroke, Alzheimer’s, inflammatory diseases, and some cancers.

In addition, liver fat can lead to non-alcoholic liver disease, fibrosis of the liver, and cirrhosis of the liver.

How Was This Study Done?

clinical studyThis study recruited 5115 participants from the Coronary Risk Development in Young Adults (CARDIA) study. This study recruited young adults (average age of 25) in 1985-1986 and followed them for 25 years. The participants were 57% female and 53% white.

As stated above, this study looked at the effect of fast foods on belly fat, muscle fat, and fatty liver (liver fat).

This study had numerous strengths:

  1. Unlike many other studies, variables like diet, fast food intake, and lifestyle were measured at multiple times during the study.
    • All participants entered treatment centers for physical exams, bloodwork, and lifestyle questionnaires at entry into the study (year 0) and again at years 2, 5, 7, 10, 15, 20, and 25.
    • On years 0, 7, 10, 15, 20, and 25 the questionnaires included the question, “How many times in a week or month do you eat breakfast, lunch, or dinner out in a place such as McDonald’s, Burger King, Wendy’s, Arby’s, Pizza Hut, or Kentucky Fried Chicken?” This question was used to calculate the number of times per week that participants ate fast food meals.
    • On years 0, 7, and 10 the quality of the non-fast-food portion of their diet was assessed by asking the participants to complete a comprehensive questionnaire about their typical intake of foods over the past month.
      • Diet quality was calculated using something called an alternative Mediterranean diet score because this calculation excludes foods commonly consumed at fast food restaurants. Thus, this calculation specifically measures the quality of the non-fast-food portion of their diet.
    • Each of these variables was averaged over the entire timespan of the study and trends (either an increase or decrease over time) were noted.
    • The outcomes of the study (belly fat, muscle fat, and liver fat) were measured at the end of the study (year 25) using CT imaging techniques.

2) The authors identified other factors that may have caused fat accumulation and corrected for them. For example:

    • Participants with the highest fast food consumption had lower educational level, lower income, poorer non-fast-food diet quality, lower physical activity, lower alcohol intake, higher caloric intake, and were more likely to be male and black.
    • Consequently, the data comparing fast food intake with fat accumulation were corrected for age, sex, race, education, income, smoking, alcohol, diet quality, caloric intake, and physical activity.

Is Fast Food Fat Food?

Fast food intake was equally divided into quintiles ranging from “Never to once a month” to “≥ 3 times per week”. When participants with the highest fast food intake over the past 25 years were compared to those with the lowest:

  • Their belly fat was higher by 48%.
  • Their muscle fat was higher by 27%
  • Their liver fat was 5-fold higher.
  • Their waist circumference (another measure of belly fat) was 11% (4 inches) more.
  • Their BMI (a measure of obesity) was 15% higher.

The authors concluded, “The results of this analysis robustly demonstrate that middle-aged adults who ate fast food more frequently over the past 25 years have significantly higher odds of MAFLD [fatty liver disease] and IAAT [belly fat]…aligned with poorer current and future cardiometabolic health [heart disease and diabetes] and chronic disease risk.”

What Does This Study Mean For You?

Several previous studies have shown that fast food consumption leads to fat accumulation and/or obesity. However, this is perhaps the best designed study on the effect of fast foods on fat accumulation and obesity to date. This is because:

  • It measured fast food consumption, non-fast-food diet quality, exercise, and many other lifestyle factors at multiple times during the 25-year study. That way we can be assured we are looking at fast food consumption and other lifestyle choices over the entire 25-year timespan of the study, not just at the beginning or end of the study.
  • The authors corrected the data for other lifestyle factors known to influence fat accumulation and obesity. Statistical corrections are never perfect, but these authors did their best to make sure the study only measured the effects of fast food consumption on fat accumulation.

Of course, this kind of study shows associations. It does not prove cause and effect. However, since 25-year double blind, placebo-controlled studies are not possible, this is perhaps the best study we may ever have.

That brings me back to your New Year resolutions. If you are like most Americans, you have probably resolved to lose weight and get healthier in past years – only to end the year fatter and less healthy than you started it.

You have probably tried dozens of diets. They worked for a while, but they were difficult to follow long term, and eventually you abandoned them.

My suggestion this year is to forget the crazy diets. Just go for a simple change. Eliminate sodas, fast foods, and convenience foods from your diet. You will lose weight. And you will be healthier. Guaranteed.

Of course, it’s not that simple. Remember that Big Food Inc has designed these foods to be addictive. Unless you have an iron will, you probably won’t be able to go cold turkey.

You may need a gradual approach. Replace sodas, fast and convenience foods one at a time. Find healthier substitutes for each fast food you replace. Then explore more convenient ways to eat healthy. It will be a journey. But the end results will be worth it.

The Bottom Line 

If you are like most Americans, you have vowed to lose weight and/or gain health in 2023. But how do you do that? There are hundreds of diets to choose from. And each diet has its “story” – a mixture of pseudo-science and testimonials – designed to convince you to try it.

Forget the pseudo-science. Forget the testimonials. Instead, focus on the one thing these diets have in common. They are all whole food diets. They all eliminate sodas, fast foods, and highly processed convenience foods.

Many studies have implicated sodas, fast and convenience foods in obesity and fat accumulation in our bodies. But these studies have all had their flaws.

A recent study looked at the association between fast food intake and 3 kinds of fat (belly fat, muscle fat, liver fat) over 25 years. All 3 kinds of fat are highly associated with metabolic syndrome (prediabetes) and several chronic diseases. More importantly, this study was designed to eliminate many of the flaws in previous studies.

When participants with the highest fast food intake over the past 25 years were compared to those with the lowest:

  • Their belly fat was higher by 48%.
  • Their muscle fat was higher by 27%.
  • Their liver fat was 5-fold higher.
  • Their waist circumference (another measure of belly fat) was 11% (4 inches) more.
  • Their BMI (a measure of obesity) was 15% higher.

The authors concluded, “The results of this analysis robustly demonstrate that middle-aged adults who ate fast food more frequently over the past 25 years have significantly higher odds of MAFLD [fatty liver disease] and IAAT [belly fat]…aligned with poorer current and future cardiometabolic health [heart disease and diabetes] and chronic disease risk.”

Simply put, the best thing you can do for your weight and your health this year is to eliminate sodas, fast foods, and convenience foods from your diet. You will lose weight. And you will be healthier. Guaranteed.

For more details 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.

 

 

Is Fructose Good For You Or Bad For You?

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Is It The Fructose Or Is It The Food?

Author: Dr. Stephen Chaney

VillainFructose is the villain of the day. It is #1 on everyone’s “No-No” list. Almost every website, blog, and diet book demonize it. Even authors I highly respect say we should absolutely avoid it.

We are told it causes obesity, diabetes, heart disease, and non-alcoholic fatty liver disease – a disease that was unheard of only a few decades ago. We are told to read labels and avoid any foods with fructose or high-fructose corn syrup listed on their label.

But wait. Isn’t fructose a natural sugar? The answer is, “Yes”. It is the main sugar in fruit and many other naturally sweet whole foods. In fact, there is the same amount of fructose in an 8-ounce soda and a medium apple.

Does that mean that fruits are also bad for us? What is the truth?

Is It The Fructose Or Is It The Food?

AppleLet me put this into perspective for you. I have covered this in detail in a previous issue of Health Tips From The Professor. Here is a brief summary.

  • There are no sugar villains. There are no sugar heroes. Most of your favorite “natural” sugars are chemically and biologically indistinguishable from high-fructose corn syrup. Other natural sugars, like agave sugar, contain more fructose than high-fructose corn syrup.
  • All the studies showing the bad effects of fructose have been done with sodas and/or highly processed foods with added sugar. Let’s be clear. Those foods are bad for you.
  • Fruits, on the other hand, are good for you. You’ve heard the old adage, “An apple a day keeps the doctor away”. A recent study showed that isn’t just an “old wives’ tale”. It is true.

Why is that? Why is fructose in sodas and junk foods bad for us and fructose in fruits good for us?

Part of the answer is that fruits are high in fiber, which slows the release of fructose into the intestine as fruits are digested. In addition, the fructose in fruits is trapped in a cellular matrix, which also slows the release of fructose during digestion.

Sodas and highly processed foods, on the other hand, have nothing to slow the release of fructose. It is immediately available as soon as the food reaches the intestine.

A recent study sheds light on why the rate of fructose release in our intestine may be important. The study showed:

  • When fructose is released slowly our bodies know exactly what to do with it.
    • Most of it is metabolized by the cells that line our intestine, and the rest is metabolized by the liver.
    • In both cases fructose is converted to glucose and slowly released into the bloodstream.
    • This stabilizes blood sugar levels.
  • When fructose is released quickly our bodies are overwhelmed and bad things happen.
    • The intestine passes the excess on to the liver, and the liver converts it to fat rather than glucose.
    • The fat is stored in the liver.
    • This leads to insulin resistance, diabetes, heart disease, and fatty liver disease.

But could the fiber in fruits have other beneficial effects such as supporting populations of beneficial gut bacteria? The study ( J Beisner et al, Nutrients, 12: 3444, 2020) I will focus on today suggests the answer is yes.

How Was The Study Done?

Clinical StudyInvestigators from the University of Hohenheim, Germany recruited 12 healthy female volunteers, ages 20 – 40 (average age = 28).

Each of the subjects was given a series of diets to follow for one week each.

  • Week one was a low fructose diet (10 g of fructose/day). For this diet phase subjects had to avoid sweets, highly processed foods, sodas, and fruits and vegetables containing more than 1 g of fructose per serving.
  • Week two was a high fructose fruit diet (100 g of fructose/day). This diet phase emphasized fructose-rich fruits and vegetables. Sweets, highly processed foods, and sodas had to be avoided.
  • Week three was a repeat of the low fructose diet (10 g of fructose/day).
  • Week four was a high-fructose corn syrup diet (100 g of fructose/day). For this diet phase subjects had to sweeten the food they were eating with a measured amount of high-fructose corn syrup. They also had to avoid fructose-rich fruits and vegetables.

The diets were designed to have around 2,000 calories/day and to have the same amounts of fat (30% of calories), protein (15% of calories), and carbohydrate (55% of calories). However, the fiber content of the diets was very different (around 17 g/day on the low fructose and high-fructose corn syrup diets and around 38 g/day on the high fructose fruit diet).

The subjects were given detailed instructions and training before starting on the 4-week program. They also kept a daily dietary record of everything they ate and drank so the investigators would know how closely they stuck to their dietary instructions.

This experimental design was based on previous studies showing that populations of gut bacteria change within 24-48 hours when you go on a new diet. Stool samples were collected at the end of each week and analyzed for gut bacteria.

Is Fructose Good For You Or Bad For You?

MicrobiomeThe study showed:

  • Consumption of a high-fructose, fruit-rich diet resulted in:
    • An increase in beneficial butyrate-producing bacteria (more about that below).
    • A decrease in bacteria associated with elevated total and LDL cholesterol.
    • Decreased blood levels of total and LDL cholesterol.
  • Consumption of a high-fructose corn syrup diet had the opposite effect. It resulted in:
    • A decrease in beneficial butyrate-producing bacteria.
    • An increase in bacteria associated with elevated total and LDL cholesterol.
    • Increased blood levels of total and LDL cholesterol.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial butyrate-producing bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

The authors said that there were probably two mechanisms for the different effects of fructose in high-fructose corn syrup and in fruits.

  • The fiber found in fruit supports the growth of beneficial bacteria in our intestine.
  • When high-fructose corn syrup is present in foods with low fiber content, it is released rapidly in the intestine. As I noted above, the cells that line our intestine become overwhelmed and pass some of that excess fructose on to our liver. However, the authors cited previous studies showing that some of that excess fructose remains in our intestine and supports the growth of unhealthy bacteria.

What Does Butyrate Do?

Question MarkYou are probably wondering what is special about butyrate-producing bacteria. Here is a brief synopsis.

  • Butyrate is a short chain fatty acid. As you might expect from its name, it was originally identified as a constituent of butter.
  • Some species of gut bacteria convert the fats in our diet to butyrate.
    • It is used as a preferred energy source for the cells that line our intestine. Consequently, butyrate production in our intestines has been linked to:
      • Reduced inflammation of the cells lining our intestine, which reduces the risk for diseases like inflammatory bowel disease (IBS) and Crohn’s Disease.
      • Reduced risk of “leaky gut syndrome”.
      • Reduced risk of colon cancer.
    • It is also absorbed into the bloodstream and appears to affect several metabolic pathways. For example, butyrate production in the intestine is associated with:
      • Decreased cholesterol levels.
      • Improved blood sugar control.
      • A healthy body weight.

What Does This Mean For You?

Questioning ManThis was a small study. As the authors noted, larger studies of longer duration are needed to confirm that the effects of fructose on our gut bacteria depend on the food the fructose is in. However, several other studies have come to similar conclusions.

More importantly, this study merely shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, while high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose are virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

The Bottom Line 

High-fructose corn syrup has been vilified in recent years. However, there is increasing evidence that it is not fructose that is the problem. It is the foods it is found in.

A recent study was designed to test that hypothesis. The investigators fed subjects high fructose diets in which the fructose came either from fruits or high-fructose corn syrup. The amount of fructose was identical in the two diets. The investigators then asked what effect the two diets had on gut bacteria. In short:

  • Consumption of the high-fruit diet increased healthy levels of beneficial gut bacteria and suppressed levels of unhealthy gut bacteria.
  • Consumption of the high-fructose corn syrup diet had the opposite effect. It increased unhealthy bacteria and suppressed beneficial bacteria.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial…bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

My take is as follows: This study shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, and high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean that high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose is virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

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.

Health Tips From The Professor