The Benefits of Protein
Beef up your knowledge of protein and good dietary sources.
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, Calif., 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 consumption of [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.