Researchers from Loughborough University and other UK institutions tested how consumption of either a dextrose drink or a protein drink after exercise affected later food consumption. They recruited 15 resistance-training men, and following a standardised breakfast and exercise routine, gave them one of the two drinks, following a randomised double-blind protocol.
Around 65 minutes after finishing their drinks, participants were offered a meal, where they could eat as much as they wished – with researchers measuring consumption.
“Energy intake was reduced after the consumption of a whey protein isolate drink compared to an energy-matched carbohydrate drink. Mean eating rate was also reduced after consumption of the whey protein drink,” wrote the researchers in an article published in the European Journal of Nutrition.
The average energy intake per meal afterwards for participants who consumed the protein drink was 3,742 kJ, compared to 4,172 kj for participants who consumed the carbohydrate drink. The eating rates were 339 kJ / minute and 405kJ / min for protein and carbohydrate recipients respectively.
Cut could help weight loss
The researchers noted the difference between trials in energy consumption was 10.3%, above the 8.9% variation shown by a previous study into variation in meal consumption, suggesting the difference was significant.
They also said their findings had implications for weight management: “It has been suggested that the daily discrepancy between intake and expenditure causing long-term weight gain is slight. Accordingly, the modest reduction in energy intake observed in the current study (430 ± 579 kJ) may augment the effects of resistance exercise in aiding long- term weight management.
“The present study suggests that a reduction in energy intake following resistance exercise with whey protein consumption may offer an additional mechanism through which body re-composition might occur,” they added.
While participants were not told the composition of the drinks during the study, they were asked to rate their perceptions of them – and when told they had consumed either protein or carbohydrate drinks at the end of the study, were able to identify which was which.
Perception differences significant
The authors said it was possible perceptions of the drinks, in addition to protein content, might have affected later food consumption.
“Within the current study, the protein drink was perceived to be thicker and creamier than the carbohydrate drink, and less pleasant. Consequently, it is probable that orosensory factors may have played a causal role in the reduction in energy intake after consumption of the protein drink compared to the carbohydrate drink.
“Whilst the failure to match drinks for orosensory factors might represent a limitation of the present study, it also increases the external validity of the study as in practice protein and carbohydrate drinks consumed in a post-exercise setting would likely differ hedonically,” they noted.
The protein in the study was provided by Volac, which had also previously funded research by one of the study’s authors – however beyond providing the materials Volac was not otherwise involved in the study.
Other authors have previously received funding from dairy industry bodies, which were similarly not involved in this study.
Source: European Journal of Nutrition
Published 2016, doi: 10.1007/s00394-016-1344-4
“Whey protein consumption after resistance exercise reduces energy intake at a post‐exercise meal”
Authors: Monteyne, A., Martin, A., Jackson, L. et al.