Meal In Young Men Research Articles

Moderate exercise reduces serum triacylglycerol concentrations but does not affect pre-heparin lipoprotein lipase concentrations after a moderate-fat meal in young men

Aerobic exercise has been shown to lower postprandial TAG concentrations after a meal(s) of high-fat content. This study examined the effects of moderate-intensity cycling on postprandial TAG concentrations and pre-heparin lipoprotein lipase concentrations after subjects consumed a meal of moderate-fat content (45 % of total energy). Twelve male subjects, aged 24 (sem 1) years, completed two 2 d trials (exercise and control) at least 1 week apart in a randomised, repeated measures design. On day 1, subjects either cycled for 30 min at 65 % of maximum heart rate in the afternoon or rested (no exercise). On day 2 of both trials, after an overnight stay with an 11 h fast, subjects consumed a test meal of moderate-fat content (0.61 g fat, 1.34 g carbohydrate, 0.37 g protein and 51 kJ energy/kg body mass) for breakfast. Blood samples were collected at baseline (before the exercise or at an equivalent time-point during the control trial on day 1), in the fasted state (0 h) and at 2, 4 and 6 h postprandially on day 2. The total and incremental areas under the serum TAG concentration v. time curve were 30 % (P = 0.039) and 33 % (P = 0.012) lower on the exercise trial compared with the control trial, respectively. Serum pre-heparin lipoprotein lipase concentrations did not differ between the exercise and control trials. These findings demonstrate that 30 min of moderate-intensity cycling performed the day before a meal of moderate-fat content is effective at lowering postprandial serum TAG concentrations but does not affect serum pre-heparin lipoprotein lipase concentrations in young men.

Protein-induced changes in energy expenditure in young and old individuals

Resting energy expenditure (EE) has recently been shown to be reduced in elderly human subjects even after adjustment for body size and composition. The present study extended this examination of EE in relation to age by comparing the thermic effect of a protein meal in young men (YM 20-26 yr, n = 9), old men (OM 70-89 yr, n = 9), and old women (OW 67-75 yr, n = 6). EE was measured before and from 1 to 6 h after presentation of 60 g protein and of a control noncaloric meal on separate occasions. Despite substantial differences in body size and composition, the protein-induced increment in EE was similar in all groups [maximum increase: YM 0.21 +/- 0.05, OM 0.17 +/- 0.12, and OW 0.17 +/- 0.04 (SE) kcal/min]. Although fasting plasma norepinephrine (NE) levels differed among all three groups (YM less than OM less than OW), NE concentrations were not affected by protein ingestion. Because protein administration acutely promotes synthesis of dopamine (DA) and serotonin (5-HT), which are both capable of stimulating EE, blockade of extraneuronal synthesis of DA and 5-HT with carbidopa, a competitive inhibitor of aromatic-L-amino acid decarboxylase, failed to suppress (and actually increased) postprandial EE. These data demonstrate that not all mechanisms responsible for EE decline with age and that protein-induced changes in EE are more a function of the oral load itself than of the size, age, or antecedent diet of the individual ingesting the protein.