Jump to Main Content
Whole-body protein turnover response to short-term high-protein diets during weight loss: a randomized controlled trial
- Pasiokos, S. M., Margolis, L. M., McClung, J. P., Cao, J. J., Whigham, L. D., Combs, G. F., Young, A. J.
- International Journal of Obesity 2014 v.38 no.7 pp. 1015-1018
- adults, body mass index, dietary protein, energy, high protein diet, isotope labeling, leucine, oxidation, protein synthesis, randomized clinical trials, weight control, weight loss
- Objective: Determine whole-body protein turnover responses to high protein diets during weight loss. Design: Thirty-nine adults (age, 21 ± 1 yr; VO2peak, 48 ± 1 ml'kg-1'min-1; body mass index, 25 ± 1 kg•m2) were randomized to diets providing protein at the recommend dietary allowance (RDA), 2X-RDA, or 3X-RDA. A 10-day weight maintenance period preceded a 21-day, 40% energy deficit. Postabsorptive (FASTED) and postprandial (FED) whole-body protein turnover was determined during weight maintenance (day 10) and energy deficit (day 31) using [1-13C]-leucine. Results: FASTED flux, synthesis, and breakdown were lower (P < 0.05) for energy deficit than weight maintenance. Protein flux and synthesis were higher (P < 0.05) for FED than FASTED, whereas feeding attenuated (P < 0.05) breakdown during weight maintenance but not energy deficit. Oxidation increased (P < 0.05) linearly between dietary protein levels, and feeding stimulated oxidation, although oxidative responses to feeding were higher (P < 0.05) for energy deficit than weight maintenance. FASTED net balance decreased linearly between dietary protein levels, but in the FED state, net balance was lower for 3X-RDA as compared to RDA and 2X-RDA (diet-by-state, P < 0.05). Conclusion: Consuming dietary protein at levels exceeding the RDA during short-term weight loss upregulates protein oxidation but does not enhance whole-body protein balance.