Research shows the role of whey protein and dairy in body composition
Research shows that whey protein, found naturally in milk, increases muscle synthesis and works in combination with resistance exercise to improve body composition.
Below are summaries of recent studies that explain the body composition benefits of whey protein.
Consuming whey protein after resistance exercise can stimulate protein synthesis
Creatine and whey protein together increase muscle fiber size and muscle strength
Whey protein isolate, not casein, improves strength and body composition
Supplementation with whey protein/creatine/carbohydrate before and after workouts enhances results
Whey protein is one of the best sources of branched-chain amino acids (BCAAs), including leucine, which has been shown to independently stimulate muscle protein synthesis in combination with exercise
This review article shares data from the USDA Food Composition Tables that show dairy products are rich sources of BCAAs and whey protein isolate is a leading source of leucine. The author cites several studies that give increasing evidence that BCAAs, specifically leucine, have a unique effect on metabolism that includes regulation of muscle protein synthesis and glucose homeostasis. The impact of BCAAs is proportional to availability and dietary intake.
Layman DK. The role of leucine in weight loss diets and glucose homeostasis. Journal of Nutrition. 2003;133:261S-267S.
Consuming whey protein after resistance exercise can stimulate protein synthesis
Ingestion of amino acids stimulates protein synthesis and results in a positive net muscle protein balance. Tipton and colleagues investigated whether consumption of casein or whey proteins have a similar beneficial effect following resistance exercise. Healthy untrained young men and women volunteers were randomly assigned to receive a drink containing either (1) 20g casein (N=7), (2) 20g whey protein (N=9) or (3) placebo (N=7) one hour after performing a bout of resistance training. Leg muscle biopsies were taken to measure net muscle protein balance. Consumption of both casein and whey proteins were found to bring about a similar positive net muscle protein balance, indicating that whole protein consumption can stimulate muscle protein synthesis after resistance exercise which over time may lead to increased muscle size and strength.
Tipton K, Elliott T, Cree M, Wolf S, Sanford A, Wolfe R. Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise. Medicine & Science in Sports & Exercise. 2004;36(12):2073-2081.
Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage
This study examined the effect of consuming a milk or soy beverage on rates of whole body and muscle protein turnover and leucine oxidation following resistance training in eight young men who regularly participated in weight lifting activities. Volunteers drank fluid milk or a soy protein beverage after a bout of weight lifting. The drinks were made from isolated soy protein or nonfat milk powder and were equal in protein (18.2g), carbohydrate (23g), fat (1.5g) and caloric (178cal) content. Results indicate that consuming a protein beverage (soy or milk) following a bout of weight lifting resulted in a positive net muscle protein balance and more muscle protein synthesis. Milk consumption after exercise resulted in a greater net muscle protein balance, and 34 percent more muscle protein synthesis compared to soy. The researchers also hypothesized that a combination of "slow" and "fast" proteins like casein and whey, both found in cow's milk, would be most effective for building muscle.
Wilkinson S, Tarnopolsky M, MacDonald M, MacDonald J, Armstrong D, Phillips S. American Journal of Clinical Nutrition. 2007;85:1031–40.
Ingesting whey protein with or without creatine after resistance exercise results in greater gains in muscle mass and knee extension strength compared to carbohydrate
Burke and colleagues tested the effects of whey protein supplementation, both with and without creatine monohydrate, combined with resistance training on muscle mass and strength. Thirty-six healthy, resistance trained males were randomly placed into one of three groups receiving supplementation* of: (1) whey protein and creatine, (2) whey protein or (3) carbohydrate placebo during six weeks of resistance training using a 4-day split routine. Males receiving whey protein (with or without creatine) had greater improvements in muscle mass and knee extension peak torque compared to those receiving a carbohydrate placebo during the six-week training program. Additionally, subjects that supplemented with whey protein and creatine had greater increases in muscle mass and bench press than the other groups. However, other measures of muscular strength such as squat strength and knee flexion peak torque were not influenced by supplementation. In conclusion, whey protein consumption during resistance training may provide some benefits over resistance training alone.
*Whey protein or carbohydrate was given at 1.2g/kg body weight/day and if applicable, creatine was given at 0.1g/kg body weight/day.
Burke D, Chilibeck P, Davison K, Candow D, Farthing J, Smith-Palmer T. The effect of whey protein supplementation with and without creatine monohydrate combined with resistance training on lean tissue mass and muscle strength. International Journal of Sport Nutrition and Exercise Metabolism. 2001;11(3):349-364.
Creatine and whey protein together increase muscle fiber size and muscle strength
Researchers from Victoria University and the University of Tasmania in Australia examined the impact of resistance exercise training and nutritional supplementation on body composition, muscle fiber size and contractile protein content, and muscle strength in a group of resistance-trained men. Twenty-six volunteers were randomly placed into one of four groups receiving supplementation* of: (1) creatine/whey protein, (2) creatine/carbohydrate, (3) whey protein only or (4) carbohydrate only. Results showed that all subjects experienced a significant increase in lean body mass following the 11-weeks of training, with the creatine/carbohydrate group experiencing a significant increase in lean body mass as compared to the carbohydrate only group. Furthermore, the creatine/carbohydrate and creatine/whey protein groups experienced greater gains in muscle fiber size compared to carbohydrate alone, while creatine/carbohydrate, creatine/whey protein and whey protein alone experienced greater gains in contractile protein content and muscle strength compared to carbohydrate only. Supplementation with whey protein with or without creatine, or creatine with carbohydrate may be more effective than carbohydrate alone in eliciting the changes in muscle size and strength that accompany routine resistance training.
*Supplements were given at 1.5g/kg body weight/day and if applicable, creatine was given at 0.1-0.3g/kg body weight/day depending on the phase of the study. Whey supplements contained 85% protein and contained minimal amounts of carbohydrate and fat, whereas the carbohydrate supplements contained only carbohydrates.
Cribb P, Williams A, Stathis C, Carey M, Hayes A. Effects of whey isolate, creatine, and resistance training on muscle hypertrophy. Medicine & Science in Sports & Exercise. 2007;39(2):298–307.
Whey protein isolate, not casein, improves strength and body composition
Cribb et al. found that whey protein isolate has a greater ability to enhance the changes in body composition and strength that accompany routine resistance exercise compared to casein. In this 12-week, double-blind study, 13 male recreational body builders supplemented* their normal diet with one of two proteins: hydrolyzed whey isolate or casein. Researchers examined the effects of protein supplementation consumed throughout the day, on strength, body composition and glutamine levels in the blood before and after a 3 days/week, 10-week resistance-training program. Results of the study indicate that the hydrolyzed whey protein isolate group achieved a significant increase in lean body mass and a significant decrease in body fat as compared to pre-training, while the casein group only showed a significant, although smaller, increase in lean body mass. Furthermore, the whey-supplemented group had a significant change in body composition (a combination of increased lean mass and decreased fat mass) as compared to the casein-supplemented group at the end of the training period. Additionally, while all subjects experienced increases in strength following the 10-week training program, the subjects who consumed whey protein showed significantly greater strength improvements in three exercises (squat, barbell bench press and cable pull-down) compared to those who consumed casein. There were no significant effects of either training or supplementation on blood glutamine levels for either group.
*Whey or casein protein was given at 1.5g/kg body weight/day.
Cribb P, Williams A, Carey M, Hayes A. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. International Journal of Sport Nutrition and Exercise Metabolism. 2006;16:494–509.
Supplementation with whey protein/creatine/carbohydrate before and after workouts enhances results
In this 10-week, single-blind, randomized study, 17 resistance trained males were matched for strength and placed in one of two groups: (1) a group who consumed a supplement* containing whey protein/creatine/glucose immediately before and after a workout or (2) a group who consumed the same supplement* in the morning before breakfast and late evening each training day. Findings of the study indicate that after 10 weeks of training (4 days/week), supplementation before and after each workout resulted in significantly greater improvements in strength and body composition (increase in lean body mass and decrease in body fat percentage) compared with those who took a supplement in the morning and late evening. The authors conclude a whey protein/creatine/carbohydrate supplement may enhance the desired changes from strength training, when taken immediately before and after a workout session.
*Supplements were provided at 1g/kg body weight/day containing 40% whey protein, 7% creatine and 43% glucose.
Cribb P, Hayes A. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy. Medicine & Science in Sports & Exercise. 2006;38(11):1918–25.