Background: High protein meals produce 3 relevant effects in weight management: i) higher thermogenic cost, ii) enhanced fat oxidation, and iii) greater satiation. Pork has been reported to be more thermogenic than soy, suggesting meat protein may be superior to plant protein in a high-protein weight loss diet context. In this study, we aimed to compare the effects of high-protein meals using meat, dairy, and soy sources respectively.
Methods: This crossover feeding trial measured energy expenditure, substrate oxidation, and satiety levels of 12 adults during 8-hour stays in a whole-room calorimeter. The 3 isoenergetic high-protein test meals (30% protein, 40% carbohydrate, 30% fat) contained predominantly meat, dairy, and soy protein.
Results: There was no significant difference between meals for effects on energy expenditure (p = 0.987), carbohydrate oxidation (p = 0.951), and fat oxidation (p = 0.997). Protein oxidation was significantly lower in meals with predominantly meat compared to soy sources (p = 0.012). There was no significant difference between meals for reported satiety levels (p = 0.296).
Conclusion: High-protein meals may be argued as beneficial for weight loss. Animal protein does not appear to offer superior energy expenditure effects, but there may be protein-sparing effects with meat, which may be beneficial in terms of retaining lean body mass.