Effect of fat-reduced diets on 24-h energy expenditure: comparisons between animal protein, vegetable protein, and carbohydrate

Background: Single-meal tests have shown that protein has greater thermogen ic and satiating effects than does carbohydrate, which may be relevant for the prevention and treatment of obesity if these effects can be maintained over 24 h. Objective: The effects of pork-meat protein, soy protein, and carbohydrate on 24-h energy expenditure were compared. Design: Twelve young, healthy, overweight and mildly obese [body mass index tin kg/m(2)): 26-32] nonsmoking men participated in a randomized, single-b lind, S-way crossover study lasting 4 d. The intervention had a 1-10-wk was hout period. The 3 isoenergetic intervention diets were as follows: pork di et (29% of energy as fat and 29% as protein, mainly from pork meat), soy di et (29% of energy as fat and 28% as protein, mainly from soy), and carbohyd rate diet (28% of energy as fat and 11% as protein). Twenty-four-hour energ y expenditure was measured in a respiratory chamber at baseline and on day 4 of each intervention period. Results: Twenty-four-hour energy expenditure was higher with the pork than with the soy (248 kJ/d, 1.9%; P = 0.05) or carbohydrate (492 kJ/d, 3.9%; P < 0.0001) diet and higher with the soy than with the carbohydrate (244 kJ/d , 1.9%; P < 0.05) diet. However, because of a higher satiating effect, ener gy intake was 10-15% lower during the chamber stay than at baseline (P > 0. 05) with all 3 diets. The differences in energy expenditure remained unchan ged after adjustment for differences in 24-h energy balance. Conclusions: Substitution of carbohydrate with 17-18% of energy as either p ork-meat or soy protein produced a 3% higher 24-h energy expenditure. The a nimal protein in pork meat produced a 2% higher 24-h energy expenditure tha n did the vegetable protein in soy.