Controversies in the Treatment of Obesity

Endocrine Society Symposium
June 16, 2004
9:30 – 11:00 AM

Reviewed by Joelle Escoffery, PhD

The goal of this symposium was to examine a variety of different strategies for the treatment of obesity.  Data addressing the efficacy of the popular low-carbohydrate diet were reviewed.  Results from four randomized trials demonstrated that low carbohydrate diets consistently produce greater weight loss and more favorable lipid effects (eg, improvements in high density lipoprotein (HDL) cholesterol and triglycerides) at 6 month follow-up, as compared with the more traditional reduced fat and reduced calorie diets. In the 2 studies that have followed participants for a year, the observed differences in weight loss no longer reached statistical significance, although there was a trend for the low carbohydrate group to show a greater weight loss. The favorable lipid effects, however, were maintained at the one year follow-up.  There are a number of hypothesized reasons why the low carbohydrate diet promotes weight loss, including increased satiety, decreased energy intake, and increased simplicity of the low carb plan.  Although this evidence may seem encouraging, it was emphasized that not enough is known about the long-term efficacy and safety of this approach (particularly in terms of bone, kidney, and endothelial outcomes) to advocate its widespread use. Another approach that was addressed was the more traditional low fat approach.  It has been shown that diets low in fat do not produce more weight loss than moderate fat diets of comparable caloric intake, although low fat diets do produce an improvement in lipid profile. This finding underscores the importance of energy restriction, as opposed to restriction of dietary fat for weight loss. In terms of weight maintenance, low fat diets are generally not a successful strategy, although it is unclear whether this finding represents a treatment failure or an adherence effect.  In the Diabetes Prevention Program (DPP), longer-term weight maintenance was achieved using this strategy, but numerous booster sessions and ongoing support were provided to assist in weight maintenance, suggesting an adherence effect. The evidence for diets based on the glycemic index was also reviewed. Currently, there is not enough evidence to advocate the widespread use of this approach. Finally, surgical interventions for obesity, such as gastric banding and gastric bypass, were addressed.  Although these approaches have been shown to reduce the incidence of type 2 diabetes and improve dyslipidemia at both 2 and 10 year follow-up, surgical intervention is a very costly approach.