John DiTraglia MD
It was with bated breath that I read an article in this week’s The New England Journal of Medicine entitled “Myths, presumptions, and facts about obesity.” (1) It started out splendidly by saying, “Passionate interests, the human tendency to seek explanations for observed phenomena, and everyday experience appear to contribute to strong convictions about obesity, despite the absence of supporting data.” They go on to say that this leads to all kinds of wrong and ineffective policy.
A myth is something that has been proven to be wrong but is still widely believed. A presumption is something that has not been proven but is still widely believed. And a fact is something that is already supported by good evidence.
These are the seven myths they picked:
1. “Small sustained changes in energy intake or expenditure will produce large, long-term weight changes.” The math never works for this because the body adjusts - my readers know that.
2. “Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and lose less weight.” It’s true that this is not going to help you lose more weight but I always think of this as just telling the truth. You’re not going to lose and keep off a lot of weight, if by a lot of weight you mean anything like half of what you would lose by obesity surgery.
3. “Large, rapid weight loss is associated with poorer long-term weight loss outcomes, as compared with slow, gradual weight loss.” Maybe doctors preach this but patients are usually not interested in this idea. Anyway, fast or slow you’re not going to keep it off.
4. “It is important to assess the stage of change or diet readiness in order to help patients who request weight-loss treatment.” There are actually Obesity Medicine Board questions that operate on this assumption.
5. “Physical-education classes, in their current form, play an important role in reducing or preventing childhood obesity.” Yeah.
6. “Breast-feeding is protective against obesity.” I have actually promulgated this idea in a repeated recent article - or at least quoted other people who espoused this idea.
7. “A bout of sexual activity burns 100 to 300 Calories for each participant.” That’s weird, I haven’t heard this myth, but I am going to go with it now.
That’s a pretty tame list of myths. What about the biggest myth of all - diet and exercise will make you lose weight and keep it off. This is only true in the sense that you can walk through fire. You can, but you really can’t reasonably.
These are the six presumptions they picked:
1. “Regularly eating (versus skipping) breakfast is protective against obesity.”
2. “Early childhood is the period in which we learn exercise and eating habits that influence our weight throughout life.”
3. “Eating more fruits and vegetables will result in weight loss or less weight gain, regardless of whether any other changes to one’s behavior or environment are made.”
4. “Weight cycling (i.e., yo-yo dieting) is associated with increased mortality.”
5. “Snacking contributes to weight gain and obesity.”
6. “The built environment, in terms of sidewalk and park availability, influences the incidence or prevalence of obesity.”
These things may well be unproved presumptions but most of them are reasonable for other reasons so just don’t say they will fight obesity. Except for snacking, the converse may be true - it’s better to snack than eat infrequently but big.
These are their nine “facts” about obesity.
1. “Although genetic factors play a large role, heritability is not destiny; calculations show that moderate environmental changes can promote as much weight loss as the most efficacious pharmaceutical agents available.” I don’t know what this means but it sounds a lot like some of the myths and presumptions.
2. “Diets very effectively reduce weight, but trying to go on a diet or recommending that someone go on a diet generally does not work well in the long term.” So this should be in the myth column.
3. “Regardless of body weight or weight loss, and increased level of exercise increases health.” Yeah, but what does that have to do with obesity?”
4. “Physical activity or exercise in a sufficient dose aids in long-term weight maintenance.” This is wrong. There’s no evidence for this if it means what it says.
5. “Continuation of conditions that promote weight loss promotes maintenance of lower weight.” What about myth #1?
6. “For overweight children, programs that involve the parents and the home setting promote greater weight loss or maintenance.” “Greater” maybe but still tiny.
7. “Provision of meals and use of meal-replacement products promote greater weight loss.” Sure but not a lot “greater” and not for long. This is an advertisement for commercial diets.
8. “Some pharmaceutical agents can help patients achieve clinically meaningful weight loss and maintain the reduction as long as the agents continue to be used.” Fair enough maybe if by “clinically meaningful” you mean health-wise but not cosmetically. This is another ad.
9. “In appropriate patients, bariatric surgery results in long-term weight loss and reductions in the rate of incident diabetes and mortality.” This is the only unequivocally true fact but who’s “appropriate?”
So, all in all, kind of a let down for me. Also there is a distressing amount of conflict of interest among the authors of this report - lots of sponsorship from food industry and drug companies.
Still there has been a lot of noise about this article in the press and I can’t wait to see the letters to the editor, including mine, that this article causes.
1.Cassaza K et al. N Engl J Med 2013;368:446-54.