The liquid on top of yogurt is whey, a protein-rich fluid that supports muscle growth.

Whey is one of the two primary proteins found in dairy, accounting for approximately 20% of the protein content in milk. During the production of yogurt, the fermentation process causes the milk to coagulate. This leads to syneresis, which is the natural expulsion of liquid whey from the protein curd structure.Scientific studies, such as those published in the Journal of the American College of Nutrition, highlight whey as a complete protein. It contains high concentrations of branched-chain amino acids, specifically leucine, which plays a critical role in muscle protein synthesis. This makes it a staple ingredient in fitness supplements and protein powders used by athletes worldwide.Beyond protein, the liquid whey found in yogurt containers is packed with potassium, calcium, and vitamin B12. Research from the University of California, Davis, suggests that discarding this liquid reduces the overall nutritional value of the snack. Keeping the whey intact ensures you receive the full probiotic benefits often associated with fermented dairy products.In the commercial dairy industry, this byproduct was once discarded, but its value was recognized in the late 20th century. Today, specialized filtration processes like ultrafiltration are used to isolate whey for use in medical nutrition and infant formula. Stirring the liquid back into your yogurt is the simplest way to consume this high-quality biological protein.