Plain language summary
Resistance exercise and post-exercise protein intake increase muscle building, and protein feeding has been shown to reduce energy intake in subsequent meals. The purpose of this study was to compare drinks containing carbohydrate (CHO, in the form of dextrose) and protein (PRO, as whey protein), consumed after resistance exercise on subsequent appetite and energy intake. 15 physically active, healthy males, who included resistance exercise in their exercise routine took part in this randomised double-blind study. After completing 50 min of leg resistance exercises they immediately ingested either PRO or CHO drink. 65 minutes after exercise they were offered a meal. The time spent eating and total energy intake were recorded, and subjects completed a questionnaire regarding their subjective appetite and sensory characteristics of the drink. The drink was provided in a randomised, double-blind manner. After the PRO drink participants consumed 10.3% less energy and eating rate was lower compared with the CHO drink. The PRO drink was perceived as creamier and thicker, the CHO drink as sweeter, more pleasant and more refreshing. Several plausible explanations exist as to why protein in drink form might be more satiating than carbohydrate: gastrointestinal appetite-related hormones; circulating amino acids; and the sensory profile of the drink. As no bloods were taken, these possible explanations could not be evaluated. The authors conclude that whilst the observed reduction in energy intake is unlikely to impair the energy provision required to optimise muscle synthesis, it may be beneficial for those individuals seeking to reduce body fat.
Abstract
PURPOSE Protein consumption after resistance exercise potentiates muscle protein synthesis, but its effects on subsequent appetite in this context are unknown. This study examined appetite and energy intake following consumption of protein- and carbohydrate-containing drinks after resistance exercise. METHODS After familiarisation, 15 resistance training males (age 21 ± 1 years, body mass 78.0 ± 11.9 kg, stature 1.78 ± 0.07 m) completed two randomised, double-blind trials, consisting of lower-body resistance exercise, followed by consumption of a whey protein (PRO 23.9 ± 3.6 g protein) or dextrose (CHO 26.5 ± 3.8 g carbohydrate) drink in the 5 min post-exercise. An ad libitum meal was served 60 min later, with subjective appetite measured throughout. Drinks were flavoured and matched for energy content and volume. The PRO drink provided 0.3 g/kg body mass protein. RESULTS Ad libitum energy intake (PRO 3742 ± 994 kJ; CHO 4172 ± 1132 kJ; P = 0.007) and mean eating rate (PRO 339 ± 102 kJ/min; CHO 405 ± 154 kJ/min; P = 0.009) were lower during PRO. The change in eating rate was associated with the change in energy intake (R = 0.661, P = 0.007). No interaction effects were observed for subjective measures of appetite. The PRO drink was perceived as creamier and thicker, and less pleasant, sweet and refreshing (P < 0.05). CONCLUSION These results suggest whey protein consumption after resistance exercise reduces subsequent energy intake, and this might be partially mediated by a reduced eating rate. Whilst this reduced energy intake is unlikely to impair hypertrophy, it may be of value in supporting an energy deficit for weight loss.
Methodological quality
Jadad score
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2
Allocation concealment
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Not applicable
