David Allison and 19 prestigious researchers have published an article in the New England Journal of Medicine on the Myths, Presumptions and Facts About Obesity. The myths they identify as being widely held are:

1. Small, sustained changes in energy intake or expenditure will produce large, long-term weight changes.

2. Setting realistic goals for weight loss is important, because otherwise patients will become frustrated and lose less weight.

3. Large, rapid weight loss is associated with poorer long-term weight-loss outcomes, as compared with slow, gradual weight loss.

4. It is important to assess the stage of change or diet in order to help patients who request weight-loss treatments.

5. Physical education classes, in their current form, play an important role in reducing or preventing childhood obesity.

6. Breast-feeding is protective against obesity.  (See my recent post on breastfeeding and obesity.)

7. A bout of sexual activity burns 100 to 300 kcal for each participant.

They go on to identify six presumptions, which are widely accepted beliefs that have neither been proved nor disproved, so that we may move forward to collect solid data to support or refute them.

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.

They authors posit nine facts that we do know about obesity. The first two are:

1. Although genetics plays a role, heritability is not destiny.

2. Diets reduce weight but trying to go on a diet o recommending someone go on a diet generally does not work well in the long-term.

The remaining facts address specific tools: physical activity, maintenance, parent-child interventions, meal replacements, pharmacology and bariatric surgery.

An excellent discussion of the myth around how many calories does it take to make one overweight is the blog from Arya Sharma.

The article does not discuss a couple of observations. First, the media is a powerful tool in perpetuating many of these myths and presumptions. Second, policy-makers, especially at the federal level, repeat these myths when they know, or should know better. Third, it may be that our brains do not do a good job in analyzing data to overcome assumptions and stereotypical views.

We will have more on the myths and presumptions and role in policy-making in the days ahead.