Low calorie diets--bolstered by suggestions on how such factors as biological rhythms can be taken into account to promote weight loss. Scanlon (Dr. Mandell's 5-Day Allergy Relief System, Overcoming Jet Lag) decided that her previous writings on diet and on body rhythms were related, so she brought them together. ""FACT"": ""You are about to participate in a boldly different kind of weight reduction and maintenance plan."" ""FACT"": ""You will receive new information that until now was unavailable from the scientific and medical community. . . you will understand for the first time what has really caused your weight gain and can master proven methods to reverse it."" With that kind of hype predominating, Scanlon explains that some of our tastes are still dictated by our ""stone age bodies"" (a strong preference for meat, for example); that the body's innate rhythms do best if most calories are consumed bejfore 4 p.m. (early meals should be protein-heavy, late meals primarily carbohydrate); and that obesity tends to run in families. She goes on to cover when and how obesity may develop; discusses common dieting glitches; and presents 1600-calorie, 1200-calorie and 800-calorie/day diets, all of which incorporate the food allergy and body rhythm considerations. A reasonable program with some new possibilities.