Leucine is an essential amino acid that helps with protein synthesis. In other words, it's a one of 9 building blocks of protein that can only be obtained from the diet. It's present in protein-rich foods including milk and other dairy products, tofu and other soy foods as well as fish, chicken and lean meat.
What's the Big Deal?
Once absorbed, leucine goes directly to muscle tissue, where it activates a chain of events that ultimately creates lean muscle. Think of it as cash to build a home-the home being muscle. When you have enough cash, you can pay the contractor to buy the equipment they need to build your home. Similarly, when you have enough leucine, your body can start making muscle protein. And the more leucine you have, the more muscle you can build.
What Does Leucine and Muscle Have to Do With Losing Weight?
On most weight loss diets, you end up losing muscle in addition to fat. That's because when you take in fewer calories than your body needs, your body has less energy to fuel basic biological functions. To make up for that, your body breaks down muscle proteins for energy. This is bad because it's your muscles that help burn calories. Here's where leucine does its magic while you lose weight; by stimulating protein synthesis it helps your body preserve muscle mass while you lose the right kind of weight-from fat, that is. In turn, your metabolism stays up, which is the key to achieving and maintaining a healthy weight for the long haul.