September 4th, 2008   

Effectiveness of low-carbohydrate, Mediterranean and low-fat diets

Findings from a two-year clinical trial show that low-carbohydrate and Mediterranean diets were more effective than a low-fat diet for weight loss in moderately obese adults. The low-carbohydrate and Mediterranean diets also had some beneficial metabolic effects. The results published in the July 17th issue of the New England Journal of Medicine suggest that these dietary strategies be considered in clinical practice.

In this two-year randomized controlled dietary intervention trial, 322 moderately obese middle age adults with a mean body mass index of 31 were assigned to one of three diets:

The overall mean weight loss for all study participants at 24 months was 4.7 kg for the low-carbohydrate group, 4.4 kg for the Mediterranean-diet group and 2.9 kg for the low-fat group. The metabolic advantages of the low-carbohydrate diet included the following improvements in cardiovascular risk markers:

The authors point out that since a similar caloric deficit was achieved in all diet groups, a low-carbohydrate, non-restricted diet may be optimal for those who will not follow a calorie-restricted diet. In addition, while maximum weight loss was achieved within 6 months, the increasing improvement in levels of some biomarkers over the course of the two-year study indicates that the diet offers health benefits beyond weight reduction.

FOR YOUR PRACTICE

This longer-term trial adds to the evidence that low-carbohydrate and Mediterranean diets are effective and safe alternatives to low-fat diets for weight loss. The more favorable effects on lipids achieved with the low-carbohydrate diet and on glycemic control with the Mediterranean diet in those with diabetes suggest that metabolic considerations and personal preferences be used to inform dietary interventions tailored for individuals.

WANT TO LEARN MORE?

Read the study, Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet, by Shai I et al. in NEJM, 2008; 359(3):229-41.

According to lead author Dr. Shai, in a communication shared by the Nutrition and Metabolism Society, their low-carbohydrate diet was based on Atkins. Participants read the book and the recipes were comparable. Typical meals included meat, poultry, fish and eggs and a variety of vegetables. Olive oil was used as the main oil for salad dressings.