Whey protein powder is derived from milk-based products. The protein is separated from liquids and is refined and dehydrated into a powdered form. This makes it not only a convenient way to increase your protein intake, but also provides one of the highest quality protein sources that is easily absorbed by the body. More specifically, close to 100% of whey protein is absorbed by the body, whereas for example with soy and plant-based protein, the body can only absorb around 50-60% of it. Since resistance training promotes a catabolic environment where muscle proteins are broken down, a highly absorbable protein source such as whey protein is ideal for after your workout. This is since it acts immediately to provide a high quality protein source to your body and prompt it to switch from a catabolic (muscle breakdown) to an anabolic (muscle repair and growth) state.
Increasing protein intake is also greatly beneficial for weight loss since it, along with carbohydrates, provides the fewest calories for a macronutrient (4 calories/gram). To put it in perspective, one serve of whey protein powder typically contains 20-25 grams of protein, and yields only between 100-150 calories. Protein is also highly satiating, which means an increased protein intake can greatly help to curb hunger and therefore assist in lowering your daily caloric intake, which is essential for weight loss.