Purpose of review
High-protein diets, often with carbohydrate restriction, are quite popular among overweight Americans pursuing strategies for weight control. Recently, well designed clinical trials have evaluated the anthropometric and metabolic effects of these diets. This review focuses on the impact of high-protein diets on energy expenditure and satiety; the diets' effects on weight loss, body composition, cardiovascular risk, and glycemic control; and potential detrimental consequences of high-protein intake.
Current evidence indicates that protein-induced energy expenditure and satiety contribute to weight control. Randomized, controlled trials continue to show comparable, if not superior, effects of high-protein diets compared with lower protein diets on weight loss, preservation of lean body mass, and improvement in several cardiovascular risk factors for up to 12 months. Evidence that chronic high-protein intake affects glucose metabolism is inconclusive at present. Further study of the long-term safety of diets with varying amounts of protein is warranted.
On the basis of patients' metabolic profiles and preferences, practitioners can recommend individualized, nutrient-rich diets within current nutritional guidelines for weight control. Diets moderately increased in protein and modestly restricted in carbohydrate and fat, particularly saturated fat, may have beneficial effects on body weight, body composition, and associated metabolic parameters. Key issues must be resolved regarding the long-term compliance and safety of chronic high-protein intake.