Individually timing high-protein preloads has no effect on daily energy intake, peptide YY and glucagon-like peptide-1.

BACKGROUND/OBJECTIVES: Gut hormones have been shown to influence energy intake (EI). To our knowledge, no study has investigated the effects of dietary patterns aimed at optimizing fullness on EI, appetite and gut hormones. SUBJECT/METHODS: To determine whether individually timing high-protein preloads would impact EI, appetite, and peptide YY and glucagon-like peptide-1 (GLP-1) levels. Ten men (body mass index = 25.5 ± 2.6 kg/m(2)) participated in a randomized crossover trial. The three conditions consisted of the self-selection of snacks (condition 1), or the consumption of a preload (300 kcal: 40% protein, 40% carbohydrates and 20% fat) at either 15 min (condition 2) or ∼ 50 min (individually set) (condition 3) before lunch and dinner. During each condition, a standardized breakfast was served, whereas lunch and dinner were self-selected from a five-item menu, and eaten ad libitum. Mealtime and daily EI were measured. Appetite, peptide YY and GLP-1 were sampled over 9 h. RESULTS: No differences in daily EI were noted across conditions (1 = 3078 ± 720 kcal; 2 = 2929 ± 264 kcal; 3 = 2998 ± 437 kcal; not significant). For the most part, daily profiles as well as premeal levels of peptide YY and GLP-1 were not different between conditions. Desire to eat, hunger and prospective food consumption were found to be lowest during condition 1 (P < 0.05). CONCLUSIONS: According to these results, it would seem that individually timing high-protein preloads does not reduce daily EI in healthy human subjects.

Normal weight men and women overestimate exercise energy expenditure.

AIM: The limited potential of exercise to induce weight loss could be partly due to the overestimation of the energy cost of exercise. The objectives of this study were twofold: 1) to investigate whether men and women are able to accurately estimate exercise energy expenditure (EE); and 2) to determine whether they have the ability to accurately compensate for the EE of exercise during a buffet-type meal. METHODS: Sixteen (8 men, 8 women) moderately active (VO2 peak=45.4±7.7 mL.kg-1.min-1), normal weight (BMI=22.8±3.3 kg/m2) individuals, aged 20-35 years, were studied. They were blinded to two randomly assigned experimental conditions: a 200 and a 300 kcal (measured by indirect calorimetry) exercise sessions that were performed on a treadmill at the same intensity (50% of VO2 peak). At the end of each exercise session individuals were asked to estimate EE of the exercise sessions and to then eat the caloric equivalent of their estimated exercise EE from a buffet-type meal. RESULTS: Estimated EE was higher than measured EE for both the 200 kcal (825.0±1061.8 vs. 200.1±0.7 kcal, P<0.05) and 300 kcal (896.9±952.4 vs. 300.2±0.7 kcal, P<0.05) sessions. Further, post-exercise energy intake was higher than measured EE for the 200 kcal (556.8±204.4 vs. 200.1±0.7 kcal, P<0.001) and the 300 kcal (607.2±166.5 vs. 300.2±0.7 kcal, P<0.001) sessions. Although post-exercise energy intake was lower than estimated EE, no significant differences were noted. CONCLUSION: These results suggest that normal weight individuals overestimate EE during exercise by 3-4 folds. Further, when asked to precisely compensate for exercise EE with food intake, the resulting energy intake is still 2 to 3 folds greater than the measured EE of exercise.