Protein provides the amino acids necessary to rebuild muscle that’s damaged during intense exercise, and fast, or simple, carbs boost insulin, which is one of the body’s primary storage hormones.
The extra insulin helps your body to use the amino acids from the protein and glycogen from the carbs more efficiently, so you rebuild more quickly. And you want to get that protein and carbs fast.
According to Tara Parker-Pope, author and columnist for the Well Blog, “The enzymes that help the body resynthesize muscle glycogen are really most active in that first 15 minutes. The longer we wait to eat something, the longer it takes to recover.”