Is casein a good post-workout protein supplement?

casein protein post workout

Is casein a good post-workout protein supplement?

Casein Protein

Casein is known as the slow protein, and for good reason. In the introductory article to the casein protein series, we discussed how casein protein consumption causes amino acid levels in the blood to increase for seven hours; more than double the time of whey protein. This would make casein a great choice for a night time meal, but, what does the research say about casein’s post-workout potential?

Protein Timing

Protein timing is a strategy used to consume protein at key times throughout the day; mainly morning, after exercise, and before going to sleep. These “anabolic windows” are thought to be the most beneficial times to consume protein. Some suggest this strategy can improve body composition and increase muscle mass. There is some research suggesting post-exercise protein consumption can have some benefits1,2.

Research: Casein vs. Whey vs. Soy

In the first study, subjects were split up into three groups: one group was the placebo and did not receive any supplement, another received casein, and the last used whey. The participants engaged in a leg extension workout and were then given 20 grams of their respective supplement. Researchers analyzed protein balance and muscle protein synthesis. The researchers concluded that both whey and casein resulted in similar increases in muscle protein balance and protein synthesis3.

In the second study, 16 participants were assigned to either a whey or casein group. Both groups consumed 24 grams of their respective protein immediately before and after exercise for eight weeks. Researchers conducted body fat analyses and performance (1-repetition max, muscle endurance, vertical jump, agility run, and broad jump) tests on the subjects before and after the eight week period.

At the end of the study, both groups saw improvements in body composition, strength, and endurance. There was no significant difference in any of the changes between the whey and casein groups4.

The next study compared the effects of whey, casein, and soy protein when consumed after a leg workout. Eighteen subjects were split into three groups representing each protein. Each group consumed ~20 grams of their respective supplement immediately following the workout. Blood was taken to analyze amino acid levels.

All three proteins caused a spike of amino acids in the blood. At 30 minutes post-consumption, the whey spike was the most pronounced, followed by soy, and then casein. At about 120 minutes post-consumption, the spike for all three proteins was similar. By 180 minutes, the amino acid levels for the whey group had fallen below the casein and soy group. Researchers in this study also looked at resting protein synthesis after consuming the three proteins. They found that whey caused a bigger increase to muscle protein synthesis than soy or casein5.

In another study, researchers compared the effects of whey and casein on protein synthesis in older adults. They found that whey protein caused a higher peak in blood amino acid concentrations than casein. Whey also resulted in higher muscle protein synthesis than casein6.

The Bottom Line – Is casein a good post-workout option?

Whey has a reputation for being the best post-workout option. While there are benefits to using whey after a workout, its practical benefits over casein are not so impressive. The research highlighted above does show that whey causes a bigger spike in circulating amino acids than casein. In practical terms, however, whey and casein perform similarly, at least according to the first two studies. The second study did not show any difference in either body fat or performance between the whey and casein groups.

For the average person, whey probably has a slight edge for being a better post-workout option. Since the edge is slight, other differences such as taste, brand, price, and availability are probably more important deciding factors than any performance advantage.


  1. Schoenfeld, B. J., Aragon, A. A., & Krieger, J. W. (2013). The effect of protein timing on muscle strength and hypertrophy: A meta-analysis. Journal of the International Society of Sports Nutrition, 10(1). doi:10.1186/1550-2783-10-53
  2. Aragon, A., & Schoenfeld, B. (2013). Nutrient Timing Revisited. Functional Foods, 65-89. doi:10.1201/b16307-5
  3. Tipton, K. D., Elliott, T. A., Cree, M. G., Wolf, S. E., Sanford, A. P., &Wolfe, R. R. (2004). Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise. Medicine  Science in Sports & Exercise, 2073-2081. doi:10.1249/01.mss.0000147582.99810.c5
  4. Wilborn, C. D., Taylor, L. W., Foster, C. A., Campbell, B., Mcadams, M., Dugan, K., & Lewing, M. (2010). The Effects of Pre- and Post-Exercise Whey vs. Casein Protein Consumption on Body Composition and Performance Measures in Collegiate Female Athletes. Medicine &Science in Sports & Exercise, 42, 774. doi:10.1249/01.mss.0000386243.94827.4e
  5. Tang, J. E., Moore, D. R., Kujbida, G. W., Tarnopolsky, M. A., & Phillips, S. M. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: Effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), 987-992. doi:10.1152/japplphysiol.00076.2009
  6. Pennings, B., Boirie, Y., Senden, J. M., Gijsen, A. P., Kuipers, H., & Loon, L. J. (2011). Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. The American Journal of Clinical Nutrition, 93(5), 997-1005. doi:10.3945/ajcn.110.008102