Pop myths about obesity

A recent study published in the New England Journal of Medicine, Myths, Presumptions and Facts About Obesity, set out to dislodge widely held views about weight loss.

Researchers identified seven popular weight-loss "facts" that, they argue, are not backed by evidence.

They argue that incorrect beliefs shared by academics, scientists and the media can lead to ineffective health policy and unhelpful weight loss recommendations by doctors.

The seven weight loss myths are:

• False - A bout of sexual activity burns 100 calories to 300 calories for each participant. The study states that "the average length of sexual activity is about six minutes, so a man in his early-to-mid 30s might expend approximately 21 calories during sexual intercourse.

• False - Rapid weight loss is associated with poorer long-term weight loss outcomes, compared with gradual weight loss. Dieticians recommend that people losing weight should not shed more than a kilogram a week. But the study showed that there was no difference in the long-term weights of people who lost fat gradually compared with those who lost it quickly.

• False - Physical-education classes, in their current form, play an important role in reducing or preventing childhood obesity. Three US studies showed that even when school children had additional physical education lessons, they did not prevent or reduce childhood obesity.

• False - Breast-feeding prevents babies becoming obese. The study quotes a World Health Organisation report that "states that persons who were breast-fed as infants are less likely to be obese later in life".

  "Breast is best" but studies that followed 13000 children over six years showed no evidence that breast feeding protected them from obesity.

• False - Setting realistic weight loss goals is better. The study found that ambitious weight loss goals could be effective.

• False - Small sustained changes in eating over the long-term lead to greater weight loss. The study suggested bigger changes in what, and how much, an obese person ate to shed kilograms.

• False - It is important to assess the stage of change or diet readiness in order to help patients who request weight loss treatment. "Readiness" for behaviour change could not predict how much weight obese people would lose.

Source: The Times