RESUMO
The effect of body composition on thermoregulation in response to a feeding regime was evaluated in eight male volunteers (21-27 years of age) during 120 min of exposure at 8, 12, and 27degrees C. Subjects were divided with respect to body fat [high fat (HF) = 19-28%, N = 4: low fat (LF) = 10-15%, N= 4] and randomly assigned the three air temperature conditions twice to examine the thermogenic effect of a sequential timed feeding regime of either a carbohydrate (CHO) or placebo (PL) beverage during exposure. Tissue insulation (I), rectal temperature (T(re)), mean skin temperature (T(sk)), metabolism (M), and respiratory exchange ratio (R) were examined. T(re), T(sk), M, and I revealed no significant differences between treatment (PL vs. CHO) at any temperature (8, 12, or 27 degrees C). However, pooled T)(sk) at 27 degrees C, and pooled I at 12 degrees C revealed significant (p < .05) differences between the LF and HF groups. In addition, at 8, 12, and 27 degrees C, pooled T(re), T(sk), and I decreased (p < .05) during the length of exposure, whereas pooled M increased (p < .05) at 8 and 12 degrees C. Pooled R increased during the length of exposure (p < .05) at 8 and 12 degrees C and differed (p < .05) between the LF and HF groups at 8 degrees C only. From these data, it appears that whereas substrate utilization differed between dietary treatment (8 degrees C) and across time (8 and 12 degrees C), there was a differential effect between LF and HF groups (T(sk) at 27 degrees C and I at 12 degrees C) that was not influenced by feeding regime.