Most protein shakes are designed to act as either meal replacements or muscle-building supplements. Shakes provide concentrated amounts of protein, which can help make you feel full, improve your body composition and stimulate muscle growth and strength. Shakes don’t work the same way for everyone, however, and they aren’t guaranteed to produce positive effects.
Protein powder is made from concentrate, isolate or a mixture of both. Concentrate has a lower percentage of protein, usually 70 percent or more, and isolate is at least 90 percent protein. A normal serving of protein powder is about 30 grams, at least 20 grams of which are protein. For women, that goes a long way toward providing the minimum recommended daily allowance of 46 grams of protein, and it’s also a significant percentage of the 56-gram RDA for men. If you don’t get much protein in your normal diet, protein shakes can deliver the nutrients necessary to build healthy muscles, bones and organs, maintain a strong immune system and regulate hormones, among other tasks.
According to an article published in 2008 in the “American Journal of Clinical Nutrition,” protein is a more satiating nutrient than fats or carbohydrates. That means protein shakes can help you feel full on fewer total calories, keep you full for longer periods of time than other foods and curb your cravings and overall calorie consumption. In one study published in 2011 in the journal “Appetite,” women who drank beverages that contained as little as 1 percent whey protein powder experienced greater feelings of satiation and consumed fewer total calories than women who drank a placebo.
Some protein shakes have scientifically proven effects on body composition. In 2011, “The Journal of Nutrition” published a study demonstrating that overweight adults who supplemented their normal diets with whey protein shakes had acquired smaller waist circumferences and lost more body fat at the end of a 23-week trial period. Those results are significant because the subjects did not attempt to cut calories or follow a regular exercise plan in conjunction with taking protein powder.
If you regularly strength-train, you may notice positive effects if you drink post-workout protein shakes. According to the National Strength and Conditioning Association, drinking protein shakes within 30 minutes of strength exercise can successfully replenish your fuel and energy levels as well as help increase muscle mass, muscle size and muscle strength. “Fast-acting” protein powders, such as whey, are most effective at encouraging post-workout gains because your body is able to digest them quickly and easily.