Poster Topical Area: Energy and Macronutrient Metabolism
Location: Hall D
Poster Board Number: 490
Effective weight loss requires targeted loss of fat mass (FM). While both caloric-restriction and exercise can reduce adiposity, the most effective strategies to maximize fat loss remain unclear.
Objectives: To determine the ability of high-protein diet (HPD) to favorably influence body composition and fatty acid oxidation (FAO) over five days of caloric-restriction (CR) in healthy, active men. HPD was hypothesized to improve retention of lean mass (LM), resulting in greater loss in FM and greater FAO both at rest and during exercise.
Methods: In this randomized, crossover trial, participants underwent three conditions: caloric-restriction with low protein intake (CRLP; 0.8 g/kg body weight (BW)); caloric-restriction with high protein intake (CRHP; 1.7 g/kg BW) and control (CON; 1.7 g/kg BW). CR was achieved by reducing energy availability to 15 kcal/kg fat-free mass (FFM), whereas energy availability was maintained at 40 kcal/kg FFM in CON. Throughout all conditions, participants completed supervised exercise sessions on a bicycle ergometer set to expend 15 kcal/kg FFM. Before and after each five-day condition, body composition was assessed via bioimpedance and FAO and peak oxygen uptake (VO2peak) were measured during an incremental exercise test.
Results: Body weight decreased (p < .001) in CRLP [-1.97 ± 0.22 kg] and CRHP [-1.80 ± 0.52 kg], but remained stable in CON. Loss of FM was significant in CRHP [-1.14 ± 0.23 kg, p < .05] but not in CRLP [-0.57 ± 0.48 kg] whereas the reduction in FFM was only significant in CRLP [-1.4 ± 0.59 kg, p < .01], but not in CRHP [-0.6 ± 0.57 kg]. Maximal rates of FAO increased (p < .01) in CRHP [+0.22 ± 0.04] and CRLP [+0.15 ± 0.06], but not in CON. VO2peak increased in only CRHP [+2.66 ± 0.74 mL/kg/min, p < .05] but not in CRLP [+1.00 ± 0.75 mL/kg/min] or CON [-0.46 ± 1.41 mL/kg/min].
Conclusions: Despite similar overall weight loss, short-term caloric restriction combined with exercise resulted only in significant fat loss when participants were provided a high-protein diet. While caloric restriction improved maximal fat oxidation independent of protein intake, only a high-protein appeared to provide modest performance improvements during short-term calorie-restricted weight loss.
University of Nebraska - Lincoln