Very fat people die earlier than people of normal weight because hypertension, diabetes and coronary disease are more frequent among the markedly obese. Most obese subjects, however, are only slightly overweight and their mortality is not elevated. Reasons for dieting are more often psychological than somatic. 2. Reducing diets are ineffective because the obese rarely follow them. Total fasting and intestinal bypass may provide better results, but are more dangerous. 3. Atkins' diet eliminates carbohydrates from food without restricting protein and fat intake. Deprived of carbohydrates, the body uses fat for fuel. A small part of metabolized fat is eliminated in the urine as ketone bodies, and this is why such diets are called "ketogenic". They have been known at least since 1863. 4. Caloric loss due to ketonuria does not exceed 100 Cal/day in the non-diabetic. It is maximal during total fasting and cannot be increased by a ketogenic diet. 5. In the short run, such diets produce rapid weight loss due to polyuria. On the other hand, refeeding carbohydrates causes water retention and weight gain. 6. The diet decreases appetite: patients eat less without feeling severe hunger and without measuring their food intake. 7. Orthostatic hypotension, fatigue, and nausea are frequent, despite what Dr. ATKINS claims. 8. The diet increases plasma cholesterol and uric acid. It may be dangerous in diabetes (anorexia, acidosis) and in heart or kidney failure (hypokalemia). 9. The diet, though far from good, is better than the book. ATKINS' theories are at best half-truths, and the results he claims lack credibility. The obese subject's disappointment with traditional reducing diets and the book's hard-sell style account for ATKINS' success.