The Benefits of Protein

Beef up your knowledge of protein and good dietary sources

By Neil Osterweil
WebMD Weight Loss Clinic - Feature

Reviewed By Charlotte E. Grayson, MD

Carbs bad, protein good.

Cased closed? Not exactly.

High protein, low carbohydrate diets are the hottest thing since sliced flank steak, and every food marketer in the known universe appears to want a piece of the protein pie.

Body builders are snatching, grabbing, and gulping down protein shakes. Dieters are gobbling down protein bars (and shunning pasta) in hopes of quick weight loss.

The Power of Protein

It's easy to understand the excitement. Protein is an important component of every cell in the body. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones and other body chemicals. In fact, protein is an important building block of bones, muscles, cartilage, skin, and blood.

Along with fat and carbohydrates, protein is a "macronutrient," meaning that the body needs relatively large amounts of it. Vitamins and minerals, which are needed in only small quantities, are called "micronutrients." But unlike fat and carbohydrates, the body does not store protein, and therefore has no reservoir to draw on when it needs a new supply.

So you may assume the solution is to eat protein all day long. Not so fast, say nutritionists.

The truth is, we need less total protein that you might think. But we could all benefit from getting more protein from better food sources.

How Much Protein Is Enough?

We've all heard the myth that extra protein builds more muscle. In fact, the only way to build muscle is through exercise. Bodies need a modest amount of protein to function well. Extra protein doesn't give you extra strength. According to the U.S. Department of Health and Human Services:

  • Teenage boys and active men can get all the protein they need from three daily servings for a total of seven ounces.
  • For children age 2 to 6, most women, and some older people, the government recommends two daily servings for a total of five ounces.
  • For older children, teen girls, active women, and most men, the guidelines give the nod to two daily servings for a total of six ounces.

Everyone who eats an eight-ounce steak typically served in restaurants is getting more protein that their bodies need. Plus they're getting a hefty amount of artery-clogging saturated fat as well.

The Drawbacks of High-Protein Diets

Many people who have jumped on the high-protein/low-carb bandwagon think that they can pack away as much protein as they like. But nutrition experts urge caution. The reasons why have to do with how high-protein/low-carb diets are thought to lead to weight loss. When people eat lots of protein but few carbohydrates, their metabolisms change into a state called ketosis. Ketosis means the body converts from burning carbs for fuel to burning its own fat. When fat is broken down, small bits of carbon called ketones are released into the bloodstream as energy sources. Ketosis, which also occurs in diabetes, tends to suppress appetite, causing people to eat less, and it also increases the body's elimination of fluids through urine, resulting in a loss of water weight.

Christopher D. Gardner, PhD, Assistant Professor of Medicine at Stanford University in Palo Alto, California, tells WebMD that high-protein diets like the Atkins' regimen may trade short-term benefits for long-term health consequences. Among the risks: The body produces ammonia when it breaks down protein. No one knows the long-term risks of higher levels of ammonia in the body.

Also, there is evidence to suggest that people who eat high protein diets typically excrete excess calcium in their urine, says Deborah Sellmeyer, MD, assistant professor of medicine and director of the Center for Osteoporosis at the University of California at San Francisco. This suggests that the body is releasing stores of calcium into the bloodstream to counteract an increase in acids caused by protein consumption (calcium buffers, or neutralizes, acids). Too much calcium loss could lead to osteoporosis down the road, Sellmeyer says.

Lastly, there are the obvious concerns. Carbohydrate foods shunned by some people on low-carb diets include fruits and vegetables, which are the best sources for vitamins, fiber and antioxidants - nutrients that help prevent disease. By contrast, animal foods that are high in protein are usually also high in saturated fats, which increase the risk for heart disease, stroke, diabetes, and several types of cancer.

The American Heart Association warns: "Reducing consumptionof [carbs] usually means other, higher-fat foods are eaten instead. This raises cholesterol levels even more and increases cardiovascular risk." The AHA also notes that by concentrating on protein sources and skipping carbs, dieters may be getting too much salt, and not enough calcium, potassium, or magnesium, which are typically found in fruits, vegetables, and whole grains.