Protein helps rebuild muscle tissue from the breakdown of intense training. Rapidly digesting whey protein is popular post-workout to kick-start the recovery process, and slowly digesting casein can help keep the process going throughout the night while you sleep. An interesting study published in The Journal of Nutrition shows how both of these dairy proteins might help reduce caloric intake.
Researchers fed obese lab rats a high-fat control diet for 8 weeks before assigning them to an experimental diet. Some got whey protein where 26% of the calories came from whey with another 14% from egg white. Casein consuming rats got 26% of their calories from casein and another 14% from egg white. Another group got a combination where 13% of calories came from whey, 13% from casein and 14% from egg white.
Food intake decreased by 17% to 37% during the first 2 weeks of a whey or casein protein diet. Fat mass was reduced by 21% to 28% with whey and between 17% and 33% with casein. The decrease in caloric intake was 18% to 34% during the first 4 days of the whey plus casein diet, and remained 30% on the 28th day of the protein diet.