Ketosis, the production of large amounts of ketones, is a normal response to fasting lasting 4 to 12 hours (e.g. between meals). The ketones are produced from fat reserves to provide fuel for muscle and so spare glucose for use by the brain. A more extreme form of ketosis occurs during starvation, and when the diet is low in carbohydrates and high in fats. Persistent ketosis is associated with muscle wasting; it may also have some other harmful side-effects. Acetone cannot be metabolised and is toxic in high concentrations. The ketones can form acids that upset the acid-base balance in the blood.
Ketogenic diets are sometimes used to reduce weight in obese people. Some depend on the idea that ketones impair appetite, so you eat less. The effectiveness of a ketogenic diet can be monitored by measuring the amount of ketones in urine; the more ketones, the more effective the diet. Simple kits are available from some pharmacists for doing this. However, most dietitians advise against using these diets.
Ketogenic diets may have a place in the therapy of people with potentially life-threatening obesity, but they should be used only under medical supervision. They are not really suitable for others; they definitely should not be used by diabetics.
The best form of weight- and fat-loss diet is one that is balanced, calorie controlled, rich in carbohydrates, and does not cause muscle loss.
Ketogenic diets are a group of high-fat, moderate-protein, and very low-carbohydrate diets given to treat some children and adolescents with epilepsy, and some adults with epilepsy and other diseases. The name ketogenic refers to the increased production of ketone bodies as a result of this special diet. Ketone bodies are three compounds that are formed during the metabolism of fats and are ordinarily excreted in the urine. An abnormally high level of ketone bodies is called keto-sis, and this condition is the goal of the ketogenic diet. It is thought that ketosis helps to control the frequency and severity of epileptic seizures, even though the reasons for this effect are not fully understood as of 2007.It has been known since Biblical times that some people with epilepsy were helped by prolonged periods of fasting, with good results. In earlier periods of history, children were kept on clear liquids for as long as two or three weeks until their seizures improved. This type of fasting, however, was obviously not sustainable as a long-term treatment. In 1921, a doctor at the MayoClinic named R. M. Wilder devised a diet for patients with epilepsy that was intended to mimic the biochemical changes that take place during fasting—ketosis, acidosis, and dehydration. Dr. Wilder’s ketogenic diet provided 10–15 grams of carbohydrates per day, 1 gram of protein for each kilogram of the patient’s body weight, and the remaining calories from fat. The calorie level was 75% of the normal daily allowance for the patient’s weight, and fluids were restricted to 80 percent. Wilder’s diet was almost identical to the protocol used at Johns Hopkins in 2007.
Until the late 1930s, the Mayo Clinic ketogenic diet was used to treat adults as well as children with epilepsy. In 1938, however, the first anticonvulsant drug—phenytoin (Dilantin)—was introduced, and was quickly followed by others. As of the early 2000s, there are 20 different anticonvulsant medications given to patients with epilepsy. After these medications were introduced, people were less interested in the ketogenic diet; many doctors considered it unnecessary or too much trouble. The number of hospitals that used it as therapy fell off sharply, while many practitioners regarded it as a “holistic” or even “alternative” treatment for epilepsy.
