You've heard talk of whey protein shakes for dieters. You read that the NBC television show "The Biggest Loser" use them. But what is it? How does it fit into a diet program? And most importantly, what can it do for you.

A whey protein shake is part of a high protein diet program. The concept is to substitute a shake for your normal breakfast meal, and perhaps even your lunch meal. Beyond that, you continue to eat in your normal, sensible manner.

The shake itself is merely whey powder blended with soy or skim milk, or even water. The whey powder can be purchased in several different flavors. Vanilla and chocolate are common flavors. Beyond the protein powder and milk, you can add fruit to add additional flavor. Strawberries, bananas and blueberries are often used in whey shakes. You can use whatever fruit you like. Some also choose to add ice.

The key to the whey protein shake is the 20 grams of protein. This is a considerable amount of protein for a single meal. In addition, it is whey protein, so it has extremely high absorption rates (in some cases 50% better absorption than egg protein). It is the amount, and the biological usefulness, that make the diet powerful.

One fact of whey protein is that is low in carbohydrates and fats. You get very few calories in a shake, and those that you do get come from the protein. A scoop of whey powder has approximately 120 calories. Skim milk has about 80 calories in 8 ounces. Combined, the shake has approximately 200 calories. When you replace a meal with a shake, you generally consumer fewer calories than you would eating the meal. Reduced caloric consumption leads to weight loss.

However, a whey protein shake may have other benefits as well. First, you'll be satisfied with the shake. Twenty grams of protein will fill you for some time. Plus, whey produces appetite suppressing hormones in the body. This prevents you from feeling hungry as well.

Whey has also been shown to increase your metabolism. A higher metabolism burns more calories, regardless of your activity level. A boost metabolism will end up burning calories during sleep.