Skim milk is often recommended as a dietary component to support muscle health, primarily due to its high-quality protein content. Scientific evidence supports the idea that consuming protein after resistance exercise helps stimulate muscle protein synthesis and aids in recovery. Skim milk provides a significant amount of complete protein—about 8 grams per cup—containing all essential amino acids necessary for muscle repair and growth. Additionally, milk proteins, especially casein and whey, are well-studied for their positive impact on muscle mass and strength, particularly when combined with resistance training.

Several clinical studies have compared milk (including skim milk) to other protein sources and have found that milk is effective in promoting muscle hypertrophy and improving body composition in both young and older adults. Skim milk offers these benefits without the added calories from fat, which may be advantageous for those seeking muscle gain without increased fat intake. However, the evidence is less robust for skim milk specifically, as most research focuses on milk in general or on isolated casein and whey proteins. Overall, while not unique to skim milk, the scientific rationale for its support of the muscle system is based on its protein quality and amino acid profile.