Scientists sort obesity facts from sales pitches


Twenty international scientists undertook an interesting task. They reviewed the available literature on things that are generally believed about obesity. They attempted to determine what is true and what is not.

The conclusions may not be perfect, but they offer better guidelines than the myths surrounding the subject and the hyperbole of salesmen.

The myths

  1. Small changes in energy intake or expenditure produce large effects over the long run. The authors point to a very old study that related 3,500 calories with a pound of weight change. The data was taken from a short-term study of men on a very low calorie diet.

Among the problems with the assumption was the failure to reflect that changes in mass modify energy requirements.

Most importantly, newer studies fail to support the myth, but beliefs die a slow, agonizing death.

  1. Gradual weight loss predicts a better long-term result than rapid weight loss. The reverse appears to be true.
  2. Readiness for a diet regimen can predict the outcome. No correlation has been demonstrated. There is one caveat: Most or all participants entering a program have some motivation. Measuring how much seems to be a wasted effort.
  3. Physical education classes reduce or prevent childhood obesity. A caution here — by me. The authors looked at a spe cific thing. They evaluated body mass index following an increased intensity of “typically provided physical education.” They only did a short follow-up.

It is reasonable to conclude that modest changes in school-based programs won’t address the childhood obesity problem.

We don’t know that school programs don’t produce interest in lifetime sports.

Most evidence I’ve seen is strongly supportive of exercise in sustaining health over the years. The authors do suggest more study of the dose-response relationship of physical activity and weight. I agree, but I’d add the effects on health and quality of life to future studies.

  1. Breast-fed children are less likely to become obese. Despite a World Health Organization report, this appears to be false.
  2. Sexual activity burns a lot of calories. If you want to read about the average length of, well, sex, and the energy expended, I’ll put it on my blog or you can check out the Jan. 31 New England Journal of Medicine.

I’ll summarize that it’s not worth it if you think that it replaces an hour in the gym.


The authors define as having neither the data to support or deny the claim conclusively:

  1. Value of breakfast. I dealt with that last time. I lean toward eating more before 3 p.m. than after, and breakfast may be a good time for more protein.
  2. Early childhood habits and weight predict adult behavior. Genetics play a role and there don’t seem to be good studies to prove the theory.
  3. Increasing fruits and vegetables will cause weight loss. The data supporting fruits and vegetables in a healthy diet seems firm. Just adding them can’t be proven to promote weight loss.
  4. Yo-yo dieting shortens your life. The problem here is that other factors make it impossible to draw conclusions. Animal studies don’t show a change in survival.
  5. It seems reasonable to me that having bike paths and walking areas are socially desirable and promote a sense of community and promote good health. Observational studies show no consistent effect on obesity. The authors say, “No conclusions can be drawn.

What does work?

Fruits, veggies and exercise promote good health, with or without weight loss. Once you are obese, it has to be dealt with as a chronic condition. School-based physical activity isn’t an answer, by itself. Family and community need to be involved.

My personal note would add that schools and community can wage economic and psychological warfare on destructive food and drink. We still think that Gatorade is a health drink and that schools should be allowed to make money off of unhealthy food and drink.

Pharmaceuticals can promote weight loss, but the risks are substantial, and they have to be used forever. Bariatric surgery can be lifesaving for the morbidly obese patient.

Allow me to get off this subject for a while. Lots of things are happening. Concepts are changing. Sincere, brilliant doctors are challenging the faith we placed in screening and pharmaceuticals. America lacks a purse big enough to pay for things that don’t work.

I must return soon to the fact that weight loss is a deceptive goal for those of us who want to live long lives with bodies and brains that serve us well.

Until I get requests for specific topics in medicine or broader fields of science, I’m available for discussions on Facebook and my blog. Both are under my name. My next topic is marijuana.

Dr. Larry Mulkerin is a retired clinical professor. He can be reached at


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