Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 28978542 · doi:10.3945/ajcn.117.159855
What was done
In a randomized crossover trial, 10 resistance-trained young men (mean ± SEM: age 21 ± 1 y, weight 88 ± 3 kg, body fat 16% ± 1%) received primed continuous stable isotope infusions and performed a single bout of resistance exercise. Post-exercise, participants consumed intrinsically labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Serial blood and muscle biopsy samples were collected over 300 minutes to evaluate whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis.
What was found
Plasma appearance of protein-derived leucine was faster after egg whites than whole eggs (P = 0.01). Total plasma leucine availability over 300 minutes was similar between whole eggs (68% ± 1%) and egg whites (66% ± 2%; P = 0.75), with no difference in whole-body net leucine balance (P = 0.27). Both conditions increased mTORC1, S6K1, and 4E-BP1 phosphorylation (all P < 0.05). Whole-egg ingestion resulted in a greater stimulation of postexercise myofibrillar protein synthesis than egg whites (P = 0.04; exact rates not reported in abstract).
Why it matters
It demonstrates that protein consumed within an intact whole-food matrix can enhance acute postprandial muscle protein synthesis more than an equivalent amount of isolated protein.
Limits
The study had a small sample size (n = 10) restricted to young resistance-trained men. It measured only acute 300-minute metabolic responses rather than long-term hypertrophy, and the whole-egg and egg-white meals were matched for protein content but not for caloric or fat content.
Cited by
- supports Human studies show that co-ingestion of fat with protein following exercise stimulates greater muscle protein synthesis than protein ingestion alone.