The Scarsdale Diet is built around ketosis, which is simply the production by the body of an unusually high amount of ketones which results in rapid weight loss. Ketones are an acidic molecule, the exact chemistry is not important. What is important for those wishing to lose weight, is getting your body to produce them. The best part is that ketones act as an appetite suppressant (read that bit again) - the chemical process of losing weight will actually supress your appetite thus leading to further weight loss - this is the beauty of the Scarsdale Diet.
Herman Tarnower M.D. did lots of research on dieting and the exact conditions reqiured to induce the body into losing weight. Here is an extract from the book (The Complete Scarsdale Medical Diet, chapter 3):
"Two words, metabolism and ketones are central to weight loss in a good diet. Sometimes, especially under proper dieting conditions, the body gets ahead of itself by burning up more fat than it does ordinarily. When this happens, your body produces an excess of ketones.
Ketones are sometimes referred to as the products of partially burned (or metabolized) fat. If you are not taking in enough carbohydrates or fats to supply your caloric needs, your system first draws upon your stored body fat to supply your energy needs. But your body does not succeed in completely consuming all the fat it attempts to metabolize in your cells. The waste products of this process - the partially burned fat, or "ashes"- are called ketones. If you are producing them, it is a sign that your body is burning off fat at an accelerated rate; you are enjoying Fast Fat Metabolism.
And that is what we want - the utilization of fat stores for calories and energy. Pulling excess fat out of the fat storage areas is an integral part of an effective reducing process; your body becomes a fat-burning machine.
One of the best things about ketones for the would-be weight loser is that they act to curb the appetite, thus making the whole dieting process less burdensome and cutting down any need you might feel for appetite depressing drugs.
Ketones are washed out of the system through the urine. This diuretic effect is a helpful, cleansing part of the increased fat-burning process.
The foods allowed on the SMD provide what has proved to be an effective combination of proteins, fats and carbohydrates. The combination of foods you eat daily on the diet causes increased body fat metabolism and the production of ketones, but not at more that a desirable level for the average adult in normal health.
The reducing diet causing ketosis never rises to levels that might be dangerous except in the following conditions: severe, uncontrolled diabetes; third trimester pregnancy, alcoholism (the problem in the alcoholic is complicated and not fully understood).