Whey and Casein Proteins for Muscle Gains

Both whey and casein proteins break down differently in your body.

It is well known that milk proteins have different rates of protein absorption and availability. Milk contains two protein fractions: whey and casein. They’re characterized as “fast” and “slow” proteins, respectively, based on their digestion rate and speed of amino acid absorption. It is well documented that whey protein results in a greater rise in protein synthesis after resistance exercise, but casein has more anti-catabolic effects resulting in longer sustained protein synthesis. For example, one study found that casein ingestion inhibited whole body protein breakdown by approximately 30 percent. It has been hypothesized that a combination of whey and casein will produce superior results in body composition due to its complementary effects of whey increasing protein synthesis fast, while casein results in a long term anti-catabolic effect.

There have been various protein supplements on the market with different ratios of whey to casein proteins. Post-exercise protein supplementation has additive effects beyond the muscle responses to exercises alone. Previous studies have shown that supplements containing whey protein alone, or combined with casein and other ingredients, improves lean body mass and upper and lower body strength gains, observed after 6-12 weeks of resistance training, compared with the ingestion of carbohydrates or other protein sources.

To compare the effects of 2 different protein supplements, varying by the ratio between whey protein (fast-digested protein) and casein (slow-digested protein), on changes in muscle size during a long-term strength training program. Subjects were assigned to two different groups with various whey to casein ratios:

– 20g of whey protein (100 percent whey)
– 10g of whey protein and 10g of casein proteins (50 percent whey and 50 percent casein) or
– 4g of whey protein and 16g of casein proteins (20 percent whey and 80 percent casein).

Subjects performed four workouts per week for nine weeks, using full body workouts. At the end of the study, ingestion of 100 percent whey protein and 50 percent casein drinks resulted in higher leucine bioavailability, compared to 20 percent whey and 80 percent casein whose composition is close to that of the milk, which contains 4g of fast protein and 16g of slow protein. Despite the greater leucine bioavailability, there were no differences between the groups in body composition. Moreover, it has been recently suggested that the use of combined fast and slow proteins intakes may be important factors predicting benefits from increased dietary protein during resistance training.

From a practical standpoint for lifters and athletes, the study suggests that although the nutritional supplement comprising a mix of high casein to whey resulted in lower aminoacidemia when compared with both whey protein (100 percent) and a whey and casein combination (50 percent whey, 50 percent casein). The researchers were quoted as stating, “What really matters to maximize the responses to resistance training is to provide a sufficient amount of high-quality proteins, at the end of exercise, and the ratio of fast-to-slow digested proteins makes little difference.” So the study suggests that consuming a high quality mixed protein drink, such as Protein Rush, is all that is needed for increases in lean muscle mass – but don’t get too caught up in the ratio of blends, as total protein seems to be the most important factor, not blend ratio.

Naclerio, F. and Larumbe-Zabala, E. (2016). Effects of Whey Protein Alone or as Part of a Multi-ingredient Formulation on Strength, Fat-Free Mass, or Lean Body Mass in Resistance-Trained Individuals: A Meta-analysis. Sports Med. 46(1):125-37.

Bosse, J.D., Dixon, B.M. (2012). Dietary protein in weight management: a review proposing protein spread and change theories. Nutr Metab (Lond). 12;9(1):81.

Fabre M, Hausswirth C, Tiollier E, Molle O, Louis J, Durguerian A, Neuveux N,  Bigard X. Effects of Post-Exercise Protein Intake on Muscle Mass and Strength During Resistance Training: is There an Optimal Ratio Between Fast and Slow Proteins? Int J Sport Nutr Exerc Metab. 2017 Apr 19:1-23.

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