ORIGINAL ARTICLE

Comparison of the effects of 52 weeks weight loss with either a high-protein or high-carbohydrate diet on body composition and cardiometabolic risk factors in overweight and obese males TP Wycherley1, GD Brinkworth2, PM Clifton3 and M Noakes2 BACKGROUND: A high-protein (HP), low-fat weight-loss diet may be advantageous for improving cardiometabolic health outcomes and body composition. To date, only limited research has been conducted in male participants. OBJECTIVE: To evaluate the medium to long-term effects of two, low-fat, hypocaloric diets differing in carbohydrate:protein ratio on body composition and cardiometabolic health outcomes in overweight and obese males. DESIGN: One hundred and twenty males (age 50.8±9.3 (s.d.) years, body mass index 33.0±3.9 kgm 2) were randomly assigned and consumed a low-fat, isocaloric, energy-restricted diet (7MJ per day) with either HP (protein:carbohydrate:fat %energy, 35:40:25) or high carbohydrate (HC; 17:58:25). Body weight, body composition and cardiometabolic risk factors were assessed at baseline and after 12 and 52 weeks. RESULTS: Sixty-eight participants completed the study (HP, n 33; HC, n 35). At 1 year both the groups experienced similar reductions in body weight (HP, 12.3±8.0 kg ( 12%); HC, 10.9±8.6 kg ( 11%); P 0.83 time group interaction) and fat mass ( 9.9±6.0 kg ( 27%) vs 7.3±5.8 kg ( 22%); P 0.11). Participants who consumed the HP diet lost less fat-free mass ( 2.6±3.7 kg ( 4%) vs 3.8±4.7 kg ( 6%); Po0.01). Both groups experienced similar increases in high-density lipoprotein cholesterol (8%) and reductions in total cholesterol ( 7%), low-density lipoprotein cholesterol ( 9%), triglycerides ( 24%), glucose ( 3%), insulin ( 38%), blood pressure ( 7/ 12%) and C-reactive protein ( 29%), (PX0.14). CONCLUSION: In overweight and obese men, both a HP and HC diet reduced body weight and improved cardiometabolic risk factors. Consumption of a HP diet was more effective for improving body composition compared with an HC diet