Why Is Weight Loss More Difficult Than It Used to Be?
Author: Dr. Stephen Chaney
If you are one of the millions of Americans who set a New Year’s goal of losing weight and eating healthier, you are to be congratulated.
However, if you are like many Americans, you are probably asking yourself “Is losing weight getting harder, or is it just my imagination?”
If you are asking yourself “Is losing weight getting harder than the first time I went on a weight loss diet?”, the answer to that question is a clear yes. It has to do with the perils of yo-yo dieting.
But here is the question that most of you never thought to ask: “Is losing weight getting harder than it was for my parents and grandparents?”
If this study (RE Brown et al, Obesity Research & Clinical Practice, 10: 243-255, 2016) is correct, the answer to that question is also yes.
How Was The Study Done?
The authors used data from The National Health and Nutrition Examination Study (NHANES), which is conducted by the CDC on an ongoing basis. For those not familiar with this program, here is a description of the NHANES program from the CDC website.
“The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States.
The survey examines a nationally representative sample of about 5,000 people per round, with 2-year data sets available for analysis. These people are located in counties across the country.
The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained medical personnel.
All participants visit the physician. Dietary interviews and body measurements are included for everyone. All but the very young have a blood sample taken and have a dental screening. Depending on the age of the participant, the rest of the examination includes tests to assess various aspects of health. In general, the older the individual, the more extensive the examination.
Health interviews are conducted in respondents’ homes. Health measurements are performed in specially-designed and equipped mobile centers, which travel to locations throughout the country. The study team consists of a physician, medical and health technicians, and dietary and health interviewers.”
In short, the NHANES dataset represents a valuable source of data for this kind of study in that it provides a 2-year snapshots of the health and nutritional status of the American population over many decades.
The authors of this study looked at the association between total caloric intake and diet composition with BMI (body mass index a measure of obesity) at 2-year intervals between 1971 and 2008. There were 36,377 US adults in this part of the study.
Because physical activity was only part of the NHANES dataset between 1988 and 2006, the correlation of physical activity with BMI was measured at 2-year intervals between 1988 and 2006. There were 14,419 adults in this part of the study.
Is Losing Weight Getting Harder?
The study showed:
- Between 1971 and 2008 total caloric intake, carbohydrate intake, and BMI increased between 10% and 14%.
Nobody was surprised by this result. Americans are eating more calories and more carbs (primarily refined carbs and sugar) than we did 30 years ago. It’s no wonder we weigh more.
- Between 1988 and 2006 physical activity increased a whopping 47-120%.
This result was a little surprising. It raises the question: “Why isn’t all this extra physical activity paying off in keeping our weight under control.
However, when the authors compared people who had the same diet (same caloric intake and same amount carbohydrate) and same physical activity with their BMI over the years they found a very surprising result.
- When they compared people eating the same diets in 1971 and 2008, the group in 2008 weighed 10% more! And this wasn’t a single data point. There was a relatively linear increase in weight between 1971 and 2008 for people consuming exactly the same diet.
- When they compared people with the same amount of physical activity in 1988 and 2006, the group in 2006 weighed 5% more! Once again, there was a relatively linear increase in weight between 1988 and 2006 for people performing exactly the same amount of exercise.
In other words, people weigh significantly more today than they did 20 or 30 years ago, even if they follow the exact same diet and exercise plans. Nobody saw this one coming.
That means it is harder to maintain a healthy weight today than it was just a few decades ago. You may have suspected this, but now you know for sure. Life isn’t fair!
The authors concluded: “Factors other than diet and physical activity may be contributing to the increase in BMI [in this country] over time. Further research is necessary to identify these factors and to determine the mechanisms through which they affect body weight.”
In other words, the real question is: “Why is weight loss more difficult than it used to be?”
Why Is Weight Loss More Difficult Than It Used To Be?
The short answer is, “Nobody knows for sure”. However, the authors raised several possibilities.
- We are increasingly exposed to persistent organic pollutants (such as pesticides, flame retardants, and chemicals in food packaging) that accumulate in our bodies and may affect how our bodies process food and store fat.
- The use of prescription drugs has risen dramatically since the 70’s and 80’s. Antidepressants, for example, are now one of the most commonly prescribed drugs in the US, and many antidepressants have been linked to weight gain. However, it’s not just antidepressants. Allergy medications, steroids, and pain medications can also cause weight gain.
- Just looking at caloric intake and diet composition (% carbohydrate, fat, and protein) obscures other major changes in our diet over the last few decades. We are eating more meat, more highly processed foods, and more artificially sweetened foods. Highly processed foods and artificial sweeteners have both been linked to weight gain.
- Our microbiome (gut bacteria) appears to be changing as well. Meat, highly processed foods, and artificial sweeteners have all been shown to influence which gut bacteria inhabit our intestines. We also know gut bacteria can influence our tendency to gain weight.
In short, a lot of things have changed over the past few decades. And these changes may be making it more difficult for us to lose weight. Some of these things, like diet and the influence of diet on our microbiome, we can control. Other things may be beyond our control.
The Bottom Line
A recent study has looked at the effect of diet and physical activity on BMI (a measure of obesity) over the past few decades.
When the authors compared people who had the same diet (same caloric intake and same amount carbohydrate) and same physical activity with their BMI over the years they found a very surprising result.
- When they compared people eating the same diets in 1971 and 2008, the group in 2008 weighed 10% more!
- When they compared people with the same amount of physical activity in 1988 and 2006, the group in 2006 weighed 5% more!
In other words, people weigh significantly more today than they did 20 or 30 years ago, even if they follow the exact same diet and exercise plans. Nobody saw this one coming.
That means it is harder to maintain a healthy weight today than it was just a few decades ago. You may have suspected this, but now you know for sure. Life isn’t fair!
For more details and to learn why it is harder to lose weight now than it was a few decades ago 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.