Protein ingestion as a dietary strategy for managing caloric intake in healthy adults

It is widely recognized that dietary protein induces greater satiety compared to carbohydrate and fat. Two separate trials were conducted to assess the use of protein as a dietary approach to manage energy intake (EI). The first, crossover trial, examined 24– hour EI after consuming a high protein bar (HP) vs. a high carbohydrate (HC) bar upon awakening on two separate days and a control, no bar day. Of the 54 participants who entered the trial, 37 subjects completed the study in its entirety. Results showed there was no significant difference in mean EI between the intervention days when the bars were consumed and the control day. The subjects consumed 1752±99 kcal on the control day, and 1846±75 and 1891±110 kcal on the days the HP and HC bars were consumed, respectively (P=0.591). However, compared to the control day, snack bar ingestion was significantly related to an increase in EI for the subjects who self-reported high weekly physical activity levels (n=11) (+22%; P=0.038 and +45%; P=0.030, HP and HC bars, respectively). These data suggest that individuals who have moderate to low physical activity levels compensate for the ingestion of energy bars (regardless of protein content) over a 24–hour period. The second parallel-arm, pilot trial examined the effect of 6 g daily gelatin ingestion vs. control on EI and weight change in healthy, overweight and obese women who initiated a walking program. Of the 37 women who entered the trial, 28 completed the six week trial. The results showed activity level (steps/d) increased in both groups (+ 22%, P=0.022). There was a significant group difference in mean EI at week 6 vs. baseline (–174±612 kcal/d and +197±320 kcal/d, P=0.001; gelatin and control groups, respectively). However, there was no significant between group difference for changes in weight, percent body fat and waist circumference. Those subjects having baseline Disinhibition scores of ≥12 gained significantly more weight throughout the study vs. those scoring <12 (P=0.004). These results indicate that daily gelatin ingestion may be a practical strategy for controlling EI among overweight and obese women initiating an exercise program.