Enhanced weight loss with protein-enriched meal replacements in subjects with the metabolic syndrome

The objective of this study was to investigate the effects of a protein-rich diet in comparison with a conventional protein diet on weight loss, weight maintenance, and body composition in subjects with the metabolic syndrome.

Obese subjects received instructions for an energy-restricted diet with a calorie deficit of 500 kcal/day and were randomly assigned to either high-protein (1.34 g/kg body weight) or conventional protein (0.8 g/kg body weight) diets for 12 months. Protein-enriched meal replacements were used to enrich one arm of the diet with protein throughout the study. In all, 67% of the participants completed the 1-year study.

Subjects following the high-protein diet lost more body weight and more fat mass compared with those on the conventional protein diet, whereas the loss of fat-free mass was similar in both diet groups. Biochemical parameters associated with the metabolic syndrome improved in both diet groups. Improvements were modestly greater in subjects with the high-protein diet. After 12 months of treatment, 64.5% of the subjects in the high-protein diet group and 34.8% of the subjects in the conventional diet group no longer met three or more of the criteria for having the metabolic syndrome.

Individuals with the metabolic syndrome achieved significant weight loss while preserving fat-free mass when treated with an energy-restricted, high-protein diet that included nutrient-dense meal replacements, as compared with the results for conventional protein intake. An intervention with a protein-enriched diet may have advantages for the management of the metabolic syndrome.