Recent evidence suggests that resting metabolic rate (RMR) is correlated with hunger and energy intake (EI) in overweight and obese adults (Caudwell et al. 2013); however, this relationship has not been examined in lean adults. Furthermore, whether pre-meal metabolic rate is associated with subsequent hunger or meal EI remains to be elucidated.
PURPOSE: To assess relationships between measures of energy expenditure (EE), hunger, and EI in lean men.
METHODS: Following an overnight fast, eight physically active men (age: 25 ± 3 y, body mass: 79.6 ± 9.7 kg, body fat 13 ± 6%; mean ± SD) completed four 10-h test days in the laboratory. Three buffet-type meals were served per test day. Prior to each meal, 30-min breath-by-breath gas measures were collected in addition to hunger ratings. One of the test days, exercise day (Ex), included a sprint interval exercise session (four “all out” 30-s running bouts) performed 1.5 h prior to lunch. The other three test days were non-exercise days (NoEx). The trapezoid method was used to calculate 10-h area under the curve (AUC) for hunger ratings and gas collections (eight per test day) to obtain total EE (TEE). Pearson correlation coefficients are reported. Relationships within subjects were analyzed with the Bland and Altman (1995) method using multiple regression analysis.
RESULTS: TEE was significantly correlated with total (3-meal) EI (TEI; Ex: r = 0.71, P = 0.05 and NoEx: r = 0.77, P = 0.03), but not with hunger AUC (Ex: r = 0.47, P = 0.24 and NoEx: r = 0.62, P = 0.10). The correlation between hunger AUC and TEI approached significance during Ex (r = 0.69, P = 0.06) but not NoEx (r = 0.34, P = 0.40). Correlations between RMR and TEI (Ex: r = 0.57, P = 0.14 and NoEx: r = 0.65, P = 0.08), and RMR and hunger AUC (Ex: r = 0.65, P = 0.08 and NoEx: r = 0.67, P = 0.07) approached significance. Relationships within subjects (96 observations) showed that pre-meal metabolic rate was correlated with hunger (r = 0.18, P < 0.001) and with meal EI (r = 0.11, P < 0.001).
CONCLUSIONS: These data appear to confirm the robustness of the relationship between RMR and EI in a sample of lean men, and extend these findings to pre-meal metabolic status despite the small sample size. Relationships between measures of EE, EI and hunger in lean adults may also be strengthened with exercise.
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