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United States Department of Agriculture

Agricultural Research Service

Research Project: BONE METABOLISM IN OBESITY Title: Dietary protein intake, energy deficit, and nitrogen balance in normal-weight adults: a randomized controlled

Authors
item Margolis, Lee -
item Cao, Jay
item Whigham Grendell, Leah
item Mcclung, James -
item Combs, Gerald
item Young, Andrew -
item Pasiakos, Stefan -

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 2012
Publication Date: April 9, 2013
Citation: Margolis, L.M., Cao, J.J., Whigham Grendell, L.D., Mcclung, J.P., Combs, G.F., Young, A.J., Pasiakos, S.M. 2013. Dietary protein intake, energy deficit, and nitrogen balance in normal-weight adults: a randomized controlled. Federation of American Societies for Experimental Biology Conference. 27:1075.11.

Technical Abstract: Consuming protein at levels higher than the recommended dietary allowance (RDA) may be metabolically advantageous for overweight and obese individuals attempting weight loss. However, the dose-response characteristics that define the optimal level of dietary protein necessary to sustain measures of metabolic homeostasis during short-term energy deficit (ED) in normal-weight adults remain unclear. Thirty-two men and 7 women participated in a 31-day randomized trial providing diets containing protein at either the RDA (0.8 g•kg-1•d-1), 2X-RDA (1.6 g•kg-1•d-1), or 3X-RDA (2.4 g•kg-1•d-1). A weight maintenance (WM, days 1-10) period was followed by 21 days of ED (days 11-31); energy intake was restricted to 60% of daily requirements. Nitrogen balance (NBAL) was assessed during WM (day 9) and throughout ED on days 14, 17, 24, and 30. Independent of protein, NBAL (mgN·kg-1·d-1) was lower (P < 0.05) at the start of ED (day 14, -40 ± 5) compared to WM (day 9, -10 ± 5). NBAL remained negative at the conclusion of ED (day 30) for RDA (-39 ± 8). However, NBAL increased (P < 0.05) rapidly and was maintained at levels comparable to WM beginning on day 17 for 2X-RDA (0 ± 8), yet failed to achieve WM levels until day 30 (-7 ± 10) for 3X-RDA. These data confirm that high protein diets conserve NBAL during short-term ED, but suggest no beneficial effect of protein at levels beyond 2X-RDA, as 3X-RDA failed to further enhance nitrogen adaptation. Supported by USAMRMC and USDA ARS

Last Modified: 10/20/2014
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