Psychological well-being response to high protein and high carbohydrate weight loss diets in overweight and obese men: Arandomised trial

Background & aims: High protein, low fat (HP) diets have established efficacy for weight management, but their effects on psychological well-being, particularly in men have not been well studied. This study compared an energy controlled HP diet with a high carbohydrate, low fat (HC) diet on psychological well-being after 1 year. Methods: 117 obese men (mean±SD, age 49.6±9.2 years; BMI 31.2±4.2kg/m²) were randomised to consumption of either an energy restricted (~7MJ/day), HP diet (n=57; 35% of total energy as protein, 40% carbohydrate, 25% fat) or an isocaloric, HC diet (n=61; 17% protein, 58% carbohydrate, 25% fat) for 52 weeks. Body weight and psychological well-being was measured with Profile of Mood States (POMS), Bachman's Self Esteem scale and the SF-36 instruments at baseline (week 0), week 12 and week 52. Results: Weight loss was (mean±SEM) 8.9±0.4kg (8.6%) at Week 12 and 10.5±0.8kg (10.5%) at Week 52 (p<0.001 for time); no difference between groups (p=0.91 time×diet effect). POMS subscales (anger-hostility, vigour-activity, confusion-bewilderment, tension-anxiety, depression-dejection, fatigue-inertia) and total mood disturbance score and the majority of SF-36 subscales significantly improved at one year (p≤0.05 for all). Self-esteem did not change significantly during the intervention (p=0.075). No effect of diet composition was evident for any of the psychometric measures assessed (p≥0.5 for time×diet effect). Conclusions: In overweight and obese men, weight loss on hypocaloric HP and HC diets were both effective in improving mood and general psychological well-being over one year.Registered under anzctr.org.au Identifier no. ACTRN 12606000002583.