Management of obesity

To the Editor: The recent article on obesity by Proietto and Baur in the Journal1 coincided with another by Campos in New Scientist,2 in which he criticised the conventional view of the risks of obesity and the norms usually accepted. Campos quoted evidence suggesting that, in fact, the group in the overweight range (body mass index [BMI], 25–30 kg/m2) are healthier than those with a BMI below 25 kg/m2. He also noted that between 1990 and 2002, despite a further increase in the prevalence of obesity in the United States, the incidence of type 2 diabetes hardly changed, while cardiovascular death rates fell. According to Campos, similar claims about the risks of obesity have been repeated over the past 50 years and relate more to cultural and political factors than to reliable scientific evidence.

Clearly, this view is inconsistent with that articulated by Proietto and Baur. While Campos’ view obviously does not apply to the grossly obese, there is a strong suggestion that the overall evidence base is inconsistent. This may be because the assumption of a linear relationship between excess weight and illness is false. It is further likely that there is confounding of variables, with weight a proxy for lack of exercise. As Campos points out, large-scale observational studies are inevitably poorly controlled.

If this is so, then it may well be more useful for the medical profession to emphasise exercise and lifestyle rather than weight loss. It may be much easier to obtain and reinforce behavioural change in these areas, and avoid the common feeling of hopelessness (“why bother”) expressed by people who find it hard to diet and to lose weight.