Effects of dietary protein on the composition of weight loss in post-menopaus al women

OBJECTIVES: To determine whether a hypocaloric diet higher in protein can prevent the loss of lean mass that is commonly associated with weight loss. DESIGN: An intervention study comparing a hypocaloric diet moderately high in protein to one lower in protein. SETTING: Study measurements were taken at the Wake Forest University General Clinical Research Center (GCRC) and Geriatric Research Center (GRC). PARTICIPANTS: Twenty-four post-menopausal, obese women (mean age = 58 +/- 6.6 yrs; mean BMI = 33.0 +/- 3.6 kg/m2). INTERVENTION: Two 20-week hypocaloric diets (both reduced by 2800 kcal/wk) were compared: one maintaining dietary protein intake at 30% of total energy intake (1.2-1.5 g/kg/d; HI PROT), and the other maintaining dietary protein intake at 15% of total energy (0.5-0.7 g/kg/d; LO PROT). The GCRC metabolic kitchen provided lunch and dinner meals which the women picked up 3 days per week and ate outside of the clinic. MEASUREMENTS: Body composition, including total body mass, total lean mass, total fat mass, and appendicular lean mass, assessed by dual energy x-ray absorptiometry, was measured before and after the diet interventions. RESULTS: The HI PROT group lost 8.4 +/- 4.5 kg and the LO PROT group lost 11.4 +/- 3.8 kg of body weight (p = 0.11). The mean percentage of total mass lost as lean mass was 17.3% +/- 27.8% and 37.5% +/- 14.6%, respectively (p = 0.03). CONCLUSION: Maintaining adequate protein intake may reduce lean mass losses associated with voluntary weight loss in older women.