At first glance, this appears to be just another diet book, but it is different. Nutritionist Waterhouse discusses the physiological reasons that make it difficult for women to lose weight and explains why changing the body composition to lose fat is more important. She then shows why diets don't work and presents a program that combines aerobic exercise, eating moderately throughout the day, choosing low-fat foods, and not eating after 6 p.m. By gradually integrating this program into their lives, women can control their weight without dieting and also improve their health. Waterhouse's advice about coping with travel, restaurant meals, and holiday meals is useful, too. Recommended for health and fitness collections.-- Barbara M. Bibel, Oakland P.L., Cal .