Optimal Weight Loss Diet to Reduce Cardiovascular Risk

Abstract & Commentary

By Michael H. Crawford, MD, Professor of Medicine, University of California, San Francisco, Chief of Clinical Cardiology, University of California, San Francisco Medical Center, Editor for Clinical Cardiology Alert.

This article originally appeared in the February issue of Clinical Cardiology Alert. At that time it was peer reviewed by Ethan Weiss, MD, Associate Professor of Medicine, Division of Cardiology, University of California, San Francisco, CA. Dr. Weiss is an advisory board member for Bionovo. Dr. Crawford reports no financial relationships relevant to this field of study.

Synopsis: The authors conclude that after weight loss, a low glycemic index and, to a lesser extent, low-protein diet may reduce inflammation associated with cardiovascular disease in overweight adults.

Source: Gogebakan O, et al. Effects of weight loss and long-term maintenance with diets varying in protein and glycemic index on cardiovascular risk factors: The Diet, Obesity, and Genes (DiOGenes) study: A randomized controlled trial. Circulation 2011;124:2829-2838.

This pan-european multicultural study investigates whether after initial weight loss in overweight subjects, a subsequent diet of high or low carbohydrate (glycemic index) or protein diets helped subjects maintain their new weight better. Their initial results showed that the low glycemic, high-protein diet was superior for maintaining their weight for 26 weeks. The present study evaluated which diet best improved hsCRP, triglycerides, cholesterol levels, and blood pressure vs a control group in 932 overweight adults who lost weight on an 8-week low-calorie diet. Of the 773 randomized to one of the four diets, 71% completed the study. Average weight loss in the low-calorie period was 11 kg. Of the subsequent diets, only the low-protein high-glycemic diet resulted in weight regain (+ 1.7 kg). Weight loss reduced hsCRP, cholesterol (HDL and LDL), triglycerides, and blood pressure. During the maintenance phase, hsCRP was reduced further in the low-glycemic diets vs high and on low protein diets vs high. Cholesterol, triglycerides, and blood pressure were not differentially affected by the four diets. The authors conclude that after weight loss, a low glycemic index and, to a lesser extent, low-protein diet may reduce inflammation associated with cardiovascular disease in overweight adults.

Commentary

With two-thirds of American adults being either overweight or obese, scientific data on appropriate diets are important. The original trial report of this study showed that caloric restriction was necessary for weight loss and diet composition had little effect. The emphasis on low-fat diets to reduce cholesterol and reduce cardiovascular risk may be thwarted if subjects substitute carbohydrates for the fat calories, resulting in little or no weight loss. As this follow-up study shows, a high glycemic index diet may also blunt the decrease in low-grade inflammation associated with weight loss and increase cardiovascular risk. Maintaining a high-protein diet also can blunt the decrease in hsCRP following weight loss, but to a much lesser extent than a high-glycemic diet. However, high-protein diets are known to improve lipid profiles. What the balance between lower LDL cholesterol and higher inflammation will do to subsequent cardiovascular risk is not known, but since cholesterol can be lowered by other means, the lower inflammation on a low-glycemic diet could be more important. In summary, this study argues for adopting low glycemic index diets with lower protein content for weight loss and maintenance.

The strengths of this study are that the subjects were otherwise healthy without diabetes, morbid obesity, and other chronic diseases. Also, the study separated the effects of weight loss from the effects of dietary composition. However, it must be emphasized that the effects of weight loss on all the metabolic, inflammatory, and blood pressure measures was greater than the effects of dietary composition.