Results of short-term acute studies have indicated that timing of protein supplementation has an important effect on the
Studies generally show that a fast digesting protein like whey is important to consume before and after training.
However slower digesting protein supplements like casein have not been studied as extensively. Using a unique experimental approach, researchers from Estonia examined the impact of timing of a
protein supplement on adaptations to training. Men performed two separate eight-week training periods with workouts always performed at 4 p.m. They consumed the casein supplement two times per day (total 70 grams per day). Subjects consumed the supplement at 10 a.m. in between breakfast and lunch, however the timing of the second dose was different during the two training periods. The subjects took the second dose 10 minutes before training (Pre-Exercise Trial) or they took it 2.5 hours after dinner at 10:30 p.m. (Late Night Trial).
The most important finding was that only the Late Night Trial showed gains in lean body mass of 2.5 pounds on average, and they also decreased fat mass by over a pound. This is the first study to show that spreading out protein doses has a more beneficial impact on body composition responses to resistance training. The likely explanation is a more sustained elevation in
levels when a slow digesting/absorbing protein source like casein is consumed in the morning and evening.
Reference: Burk A, Timpmann S, Medijainen L, Vähi M, Oöpik V. Time-divided ingestion pattern of casein-based protein supplement stimulates an increase in fat-free body mass during resistance training in young untrained men. Nutr Res. 2009 Jun;29(6):405-13.