Whey protein is widely used as a dietary supplement for weight loss, and its efficacy is supported by a substantial body of scientific research. Multiple randomized controlled trials and meta-analyses have shown that whey protein supplementation can aid in weight loss, primarily by promoting satiety, preserving lean muscle mass during calorie restriction, and supporting increased fat loss compared to carbohydrate or fat supplementation. Whey is a complete protein with a high biological value, and its rapid digestion leads to a significant increase in the release of hormones such as GLP-1 and PYY, which help reduce appetite.

Studies have consistently demonstrated that individuals consuming whey protein as part of a calorie-restricted diet or combined with resistance training tend to lose more fat mass and retain more lean mass compared to those not using whey or using other protein sources. For example, a 2014 meta-analysis published in the Journal of the American College of Nutrition found that whey supplementation significantly reduced body weight and fat mass while preserving lean tissue. However, while the effects are statistically significant, it should be noted that they are generally modest and most pronounced when whey is used as part of a structured dietary and exercise regimen.

Overall, the scientific evidence supporting the use of whey protein for weight loss is robust, though it is not a standalone solution and works best alongside diet and lifestyle changes.