High-protein meals may benefit fat oxidation and energy expenditure in individuals with higher body fat


  • M. Batterham, PhD, APD, Post Doctoral Fellow
    R. Cavanagh, MND, APD, Dietitian
    A. Jenkins, PhD, Associate Professor
    L. Tapsell, PhD, FDAA, Professor
    G. Plasqui, PhD, Associate Lecturer
    P. Clifton, PhD, Professor

M. Batterham, School of Health Sciences, University of Wollongong, Northfields Ave, Wollongong, NSW, 2522. Email: marijka@uow.edu.au


Aim:  Fat oxidation is impaired in obesity. The aim of the present study was to determine if fat oxidation, seen in a high-protein meal response, was influenced by body composition.

Methods:  Subjects were provided with control (14% protein, glycaemic index, GI 65), high-protein high-GI (33% protein, GI 74) and high-protein low-GI (35% protein, GI 45) meals. Substrate oxidation and energy expenditure were measured in room calorimeters over eight hours in 18 subjects. Results were compared using a repeated-measures anova with a customised post-hoc analysis (to compare the protein diets averaged vs control and to compare the low- and high-GI diets) and covariates in a linear model of the form: y = α + β1 × fat-free mass (kg) + β2 × loge fat mass (kg).

Results:  The full model found significant meal effects on fat oxidation (0.21 ± 0.21 kcal/minute high-protein high-GI, 0.34 ± 0.11 kcal/minute high-protein low-GI, 0.55 ± 0.2 kcal/minute control, F = 3.50, P = 0.007). The effect on energy expenditure (1.67 ± 0.07 kcal/minute high-protein high-GI, 1.61 ± 0.08 kcal/minute high-protein low-GI, 1.67 ± 0.08 kcal/minute control) approached significance (F = 2.45, P = 0.070). Post-hoc analysis revealed a protein effect (P = 0.004 for fat oxidation and P = 0.030 for energy expenditure). Significant interactions indicated that meal response was influenced by body composition. The high-protein meals eliminated the negative relationship between body fat and fat oxidation (α = −4.7, β2 = 2.23, P < 0.01) and between body fat and energy expenditure, which were evident in the control meal (α = −1.5, β2 = 0.63, P < 0.05). No effect of GI was evident.

Conclusion:  High-protein intakes may ameliorate an obesity-induced decline in fat oxidation.