High-protein diets are generally well tolerated by healthy adults. But a dramatic increase in protein-rich foods may be dangerous for people with liver or kidney disease. This is because they lack the ability to get rid of the waste products left from protein metabolism.

Protein is essential to human life — every cell in your body has it. Your skin, bones, muscle and organ tissue all contain protein. It's found in your blood, hormones and enzymes as well.

Your body can store only small amounts of excess protein. During digestion and metabolism, protein is broken down into amino acids. These are the building blocks of protein. Next, nitrogen is removed from these extra amino acids. The nitrogen is processed by your liver and then excreted in urine as waste.

Your body uses amino acids to make enzymes and other essential proteins. It also uses amino acids for energy. Any amino acids that your body doesn't use for building other proteins or for energy are eventually converted into fat.

Although high-protein diets generally aren't harmful for people in good health, they may increase the risk of kidney stones and osteoporosis. They may also limit disease-fighting foods, such as fruits, vegetables and whole grains. In addition, many high-protein foods — such as meat, milk and eggs — are high in fat and cholesterol. So choose your sources of protein wisely. Good choices include fish, beans and lentils, which are lower in fat and cholesterol, and low-fat dairy products.

If you have kidney or liver disease or any chronic health condition, talk to your doctor before starting a new diet.