Find out how consuming too much protein can harm your body.

By Miriam Nelson
WebMD Feature

Reviewed By Gary Vogin

Seems like everyone at the gym is doing it: filling up on protein to bulk up those biceps. But it's a misconception. Eating extra protein actually doesn't do much toward boosting your muscle mass and strength.

In fact, medical research shows that consuming too much protein -- more than 30% of your total daily caloric intake -- could actually harm your body, says protein expert Gail Butterfield, PhD, RD, director of Nutrition Studies at the Palo Alto Veterans' Administration Medical Center and nutrition lecturer at Stanford University.

She says that a diet containing excess protein can have the following adverse effects:

* Adding more protein but not more calories or exercise to your diet won't help you build more muscle mass, but it may put your other bodily systems under stress.
* .
* Eating more protein and increasing total caloric intake while maintaining the same exercise level will build an equal amount of additional fat and muscle mass, according to a study published in 1992 in the Journal of the American Geriatrics Society.

Too Much Protein

So think twice when you consider sacrificing the carbohydrates for a protein-dominant diet, Butterfield says. Drastically cutting carbohydrates from your diet may force your body to fight back.

She says that's because a diet in which protein makes up more than 30% of your caloric intake causes a buildup of toxic ketones. So-called ketogenic diets can thrust your kidneys into overdrive in order to flush these ketones from your body. As your kidneys rid your body of these toxic ketones, you can lose a significant amount of water, which puts you at risk of dehydration, particularly if you exercise heavily.

That water loss often shows up on the scale as weight loss. But along with losing water, you lose muscle mass and bone calcium. The dehydration also strains your kidneys and puts stress on your heart.

And dehydration from a ketogenic diet can make you feel weak and dizzy, give you bad breath, or lead to other problems.
How Much Protein Do I Need?

The amount of protein you require depends on your weight and your daily caloric intake. Most Americans consume more than enough protein in their daily diets. A few specific groups of people are at risk for being protein-deficient, including elderly women and people with illnesses or eating disorders. A protein deficiency is defined as eating 50% to 75% of the recommended amount of daily protein, Butterfield explains.

Ideally, you should consume 0.36 grams of protein for every pound of body weight, according to recommended daily allowances (RDA) set by the Food and Nutrition Board. So if you weigh 170 pounds, you need about 61 grams of protein each day.

Protein should also make up approximately 15% of your total daily caloric intake, also according to the RDA. In a diet of 1,800 calories a day, for example, about 270 of those calories should come from protein.
It's Essential

Although limiting protein intake is important, you should also realize that protein is essential to our bodies' normal functions. It assists in synthesizing enzymes and hormones, maintaining fluid balance, and regulating such vital functions as building antibodies against infection, blood clotting, and scar formation.

Protein is also a building block for our muscles, bones, cartilage, skin, hair, and blood. Protein-rich foods include meat, cheese, milk, fish, and eggs. For vegetarians, protein can be found in soy products such as tofu as well as in combinations of foods, such as rice or corn with beans.

Whether you are an avid strength trainer, a marathon runner, or just an average exerciser, a balanced diet that is rich in fruits, vegetables, whole grains, lean meats, fish, and complex carbohydrates is what nutritionists recommend.

Reviewed by Gary D. Vogin, MD, May 29, 2002.

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Last Editorial Review: 1/30/2005 10:56:15 PM