Non-proven presumptions regarding obesity

In last week’s blog we reviewed part of an article from the Jan. 31, 2013 edition of the New England Journal of Medicine. In “Myths, Presumptions and Facts about Obesity” (NEJM 2013: 368;446), authors reviewed the scientific data regarding common assumptions about the causes, approaches to, and treatment of this common condition. 

Seven “myths” were reported on: small sustained changes in energy intake or expenditure will produce large, long term weight changes, setting realistic goals in obesity treatment is important because otherwise patients will become frustrated and lose less weight, large and rapid weight loss is associated with poorer long term weight loss outcomes than slow gradual weight loss, assessing the stage of change or diet readiness is important in helping patients who seek weight loss treatment, physical education classes in their current format play an important role in preventing or reducing childhood obesity, breast feeding is protective against obesity, and a bout of sexual activity burns 100-300 calories.  The authors did not find scientific data supporting these beliefs.

The second category discussed were “presumptions”-defined as widely accepted beliefs for which there is no significant scientific evidence supporting or refuting their utility. These presumptions are:

1. Regular eating (versus skipping) breakfast is protective against obesity.   This is not to say that breakfast isn’t important, but rather that this should not be counted on as a core part of a weight lost strategy

2. Early childhood is the period during which we learn exercise and eating habits that influence our weight throughout life.  Although it’s true that childhood obesity is a strong predictor of adult obesity, there is evidence of strong genetic component to this finding. No studies have shown an association between healthy childhood habits and lowered obesity in adulthood—but the issue may be that such a study has not been done rather than the presumption is incorrect

3.Eating more fruits and vegetables will result in weight loss or less weight gain, regardless of whether one makes other changes.  Fruits and vegetables are healthy and essential, but an increase in their intake with no other lifestyle changes has not been shown to be a consistent and effective weight loss strategy.

4.Weight cycling (i.e. “yo-yo” dieting) is associated with increased mortality No data to support.

5.Snacking contributes to weight gain and obesity. Makes sense, but not proven.

6.The built environment, in terms of park and sidewalk availability, influences obesity.  This would seem like an important study for community planners to undertake.

To underscore, the presumptions above MAY ALL BE TRUE—however the authors of the New England Journal of Medicine article were not able to find support evidence for them.

Next week we will complete the review of the article and focus on FACTS regarding obesity.