Certain enzymes and hormones are elevated in your body after you exercise. Anabolic hormones build up muscle and help your body adapt to the exercise you just did. Immediately after exercise, anabolic hormones increase and your body is more readily able to use what you put into it. Generally, excess protein gets turned into glucose or stored as fat, but after exercise, any proteins that you take in can be utilized.
Proteins are rated according to their quality and digestibility. When your body is able to thoroughly digest and use a protein it is considered to be of high quality. The protein digestibility-corrected amino acid score, or PDCAAS, does just this. It gives proteins a rating based on their quality and usability. Ratings extend from zero to 100 percent; the higher the score, the better the protein.
You should replenish lost protein after exercise with low fat food sources, according Michael Colgan, author of "Optimum Sports Nutrition." Although it may not seem like an appetizing post-workout meal, fish such as flounder, orange roughy, albacore tuna, crab and salmon provide 20 to 24 g of protein per 100 g serving with only 1 to 5 g of fat. Most fish rate at about an 80 percent on the PDCAAS scale.
Eggs are a high quality source of protein to eat after you exercise. Eggs rate at a 100 percent of the PDCAAS. They are an all-around good protein that provides most of the essential amino acids that are needed in your diet. They are easily digestible and your body will put most of the proteins to use immediately.
Milk is another protein that rates at a 100 percent of the PDCAAS. Milk may be even more effective at providing good dietary protein because it is liquid. Liquid protein moves quickly through the stomach and into the small intestine where digestion and absorption occurs. A 2006 study published in the "International Journal of Sport Nutrition and Exercise Metabolism" evaluated the effects of chocolate milk as a recovery drink after an intense bout of exercise, compared to a carbohydrate-only replacement drink. The researchers found that chocolate milk staved off fatigue and allowed athletes to work longer.
How you take in protein after exercise also depends on your exercise goals. For example, if you are an endurance-type athlete, you should also have carbohydrates with your protein. Muscle glycogen synthesis is elevated after exercise as well. If this is also a goal, then milk is more effective than eggs. Milk provides not only a good source of protein, but also lactose, a high quality carbohydrate. According to a study published in the "American Journal of Clinical Nutrition" in 2000 by Luc JC van Loon and colleagues, a mixture of protein and carbohydrates after exercise increases muscle glycogen storage.