Background: Obesity and its comorbidities are worldwide problems. Approaches to reducing obesity and its associated metabolic derangements typically emphasize fat and energy restriction, but for many achieving and maintaining weight loss is difficult. Diets that focus on substantially altering macronutrient distribution rather than energy restriction are promising alternatives, but have generally included large amounts of protein, fiber or fat.
Objective: To compare the effects of dietary advice including moderate increases in protein and fiber without specifying energy intake with standard low-fat, high-carbohydrate dietary recommendations on body composition and metabolic risk factors.
Methods: 89 overweight or obese women aged 18-65 years were randomized to either a standard diet that was intended to be low in fat and relatively high in carbohydrate (n=42) or to a relatively high-protein (up to 30% of energy), relatively high-fiber (>35g per day; HPHF) diet (n=47) for 10 weeks. Advice regarding strict adherence to energy intake goals was not given.
Results: Participants on the HPHF diet lost more body weight (1.3kg; 95% CI, 0.7, 1.9; P<0.0001), total fat (1.0kg; 95% CI, 0.2, 1.8; P<0.0001) and truncal fat (0.7kg; 95% CI, 0.1, 1.3; P=0.034) than participants on the standard diet. Total cholesterol and low-density lipoprotein (LDL) cholesterol were also significantly lower after the HPHF diet.
Conclusion: An ad libitum diet relatively high in both protein and fiber improved body composition and metabolic risk factors compared with standard dietary advice.