Low carbohydrate diets are the current craze (Atkins, South Beach, ect.). They work by eliminating carbohydrates completely from the diet. Without any carbs, one would be eating only fat and protein. The brain depends on sugar as its fuel, as it cannot use fat or protein. When one cuts out the carbs from their diet the body quickly uses up its stored carbohydrate (glycogen). Once these stores are used up, all the body has left to burn are fat and protein. The body converts fat to ketones which the brain can use as fuel. This process is called ketosis and is an emergency measure the body uses to save its muscles and vital organs. In other words, the body reacts as if it is starving. Ketosis causes suppression of the appetite which helps with weight loss. Furthermore, a large amount of initial weight loss is due to loss of water not fat. One problem with low carb diets, is that when one subsequently eats some carbs the body thinks it is no longer starving and stops producing ketones. The appetite suppression effect is no longer present and hunger takes over and one will crave carbs. Water weight is then rapidly regained. Another problem with low carb diets, is the large amount of fat, especially saturated fat that is eaten on low carb diets. Saturated fat is turned into LDL cholesterol (the bad stuff) by the liver. This is why cholesterol levels do not change much on low carb diets. High LDL cholesterol then leads to a higher risk of heart attack and stroke. Finally, low carb diets depend on people eating large amounts of protein. High amounts of dietary protein can directly lead to kidney damage. Moreover, high dietary protein can lead to calcium being lost through the urine. This then results in an increased risk of kidney stones and osteoporosis. Animal protein lacks disease and cancer preventing nutrients and antioxidants. Fruits, which tend to be avoided on low carb diets are loaded with fiber and antioxidants. Any diet that limits high nutrient, antioxidant, and fiber rich foods needs the be seriously reconsidered.