Clinical Question

Are low glycemic index or low glycemic load diets effective in the treatment of obesity?

Evidence-Based Answer

Compared with high glycemic index diets or conventional energy-restricted weight loss diets, low glycemic index diets better reduce body mass index (BMI) and low-density lipoprotein (LDL) cholesterol. The weighted mean difference showed that patients lost an additional 1 to 2 BMI units on the low glycemic index diets.

Practice Pointers

There are a number of treatments for obesity that have been proven effective, especially over the short term. Behavior and cognitive behavior therapy are effective, especially when combined with diet and exercise.¹ Surgery results in greater weight loss than conventional treatments and improves quality of life, hypertension, and diabetes. However, it has a significant risk for morbidity and mortality.² There is some evidence that anti-obesity agents such as orlistat (Xenical) and sibutramine (Meridia) promote weight loss, but studies have had methodological problems.³ Exercise and diet are effective. Exercise improves cardiovascular disease risk factors even when participants do not lose weight.⁴ Fat-control and calorie-control diets achieve weight loss.⁵

In this review, low glycemic index diets have been shown to be more effective than low-calorie or higher glycemic index diets. The authors found six randomized controlled trails (N = 202). Study interventions were at least five weeks. The longest studies had a six-month intervention with a six-month follow-up. No studies reported on adverse effects, mortality, or quality of life. Compared with other diets, low glycemic index diets resulted in statistically and clinically significant reductions in BMI, LDL cholesterol, and total fat mass. There was a reduction in insulin resistance, but not fasting morning insulin. Longer-term studies on treatment for obesity are needed.