Carbohydrate energy‐replacement attenuates protein turnover and promotes nitrogen retention during acute periods of increased metabolic demand (820.8)

Acute periods of increased metabolic demand and subsequent energy deficit increase protein loss. To examine whether consuming an energy‐replacement based primarily on carbohydrate (85%) with negligible protein (2%) attenuates protein loss during highly metabolic energy flux, whole‐body protein turnover ( 15 N‐glycine) was measured in 23 adults at baseline and after 2‐days of increased metabolic energy expenditure ([mean ± SD] 1800 ± 350 kcal·d ‐1 ) once in energy balance (BAL) and on a separate occasion during energy deficit (DEF, 90%). Turnover was the same at baseline for both trials. After DEF, protein flux, synthesis, and breakdown rates were higher and net balance was lower than after BAL (time‐by‐energy , P < 0.05). Within trials, protein flux decreased for BAL but remained constant for DEF (time‐by‐energy, P < 0.05). Synthesis and breakdown decreased over time during BAL, whereas synthesis remained steady and breakdown increased 36% during DEF (time‐by‐energy, P < 0.05). Thus, net protein balance was maintained during BAL but was negative at the end of DEF (‐0.7 ± 0.4 g·kg ‐1 ·d ‐1 ; time‐by‐energy, P < 0.05). These data confirm the detrimental effects of energy deficit on protein balance and indicate that, by attenuating protein turnover, a carbohydrate‐based energy replacement can promote nitrogen retention during acute periods of increased metabolic demand. Grant Funding Source : USAMRMC and DMRDP