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Myths About Obesity Rest on Slim Evidence

By Dr. David Lipschitz Modified: February 23, 2013 at 4:03 pm •  Published: February 23, 2013
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Much of what we believe about obesity may be incorrect.

The New England Journal of Medicine recently published "Myths, Presumptions and Facts About Obesity," a paper from scientists at nutritional centers in the United States and abroad. They suggest that many common beliefs regarding obesity are not supported by scientific evidence (they are presumptions) or that information suggests the beliefs to be incorrect (myths).

This paper raises serious questions about our understanding of obesity.

Here are beliefs the authors identify as myths.

Myth: Reducing calorie intake or increasing exercise over prolonged periods of time leads to significant weight loss, so slightly reducing food intake while adding moderate exercise can lead to an annual weight loss of 10 pounds. Research shows that for most people, the loss is more like 2 pounds annually.

Myth: It is important to set realistic weight loss goals, and failure to do so leads to frustration, limiting weight loss. New research indicates that the more ambitious the weight loss goals, the better.

Myth: Rapid weight loss is less likely to succeed in the long term compared with slow, gradual weight loss. Remarkably, research indicates that rapid initial weight loss leads to a higher chance of success.

Myth: To be successful, someone must be ready and committed to weight loss. In fact, initial attitude about weight loss does not appear to predict success.

Myth: Physical education programs help to prevent childhood obesity. Sadly, a number of research studies have shown that frequent supervised exercise programs at school do not affect weight.

Myth: Being breastfed reduces the lifetime risk of obesity. A recent analysis of World Health Organization information shows this is not true.

Myth: Increased sexual activity helps weight loss. It was said that sexual activity expends up to 300 calories, but research has shown that the actual calories expended are typically 3.5 per minute.

And here are beliefs not supported by scientific evidence (presumptions).

1. Eating a big breakfast helps prevent weight gain by reducing hunger later in the day. One study stated that breakfast habits showed no impact on weight, while another showed some benefit.

2. Eating more fruits and vegetables helps weight loss. While they are healthy for you, studies show that merely eating these foods without making other behavioral changes may not promote weight loss.

3. Early childhood habits in regard to exercise and diet affect weight in later life. Evidence suggests that genetic factors, not habits, affect weight in later life.

4. Weight cycling increases the risk of dying. It is better to maintain a stable weight than to lose and gain weight repetitively. Although there is some truth to the observation that weight cyclers (yo-yo dieters) often have health problems, studies have not been done that prove cause and effect, and many experts question the validity of this belief.

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