The author of Maggie's Back Book and Maggie and the Beautiful Machine sounds off, now, on a conglomeration of subjects. The tally: reliable on exercise, flakey on diet, sketchy on everything else. Setting out to tell about the ""Years of Our Lives"" (menstrual, pregnancy, menopausal, and older), Maggie hops from subject to subject offering unsubstantiated advice: to combat menstrual irregularity, ""gain a little weight, not in muscle but in body fat"" (how?); to prevent premenstrual syndrome, increase potassium intake, while loading up with vitamin C to prevent extra bruising (why?); and, as wrinkles are the result of gravity's drag on the body (really?), sleep with the foot of the bed elevated to counteract the pull. Next come some--more reasonable--exercises, arranged by body area (face and neck, the lower body, ""Joint Fluid Warm-Ups""), but with some curious additions: a section on balance and dizziness counsels us on how to counteract the effect of inner-ear infections, low blood pressure, anemia, and other maladies, without discussing how or if these problems could be eliminated. Maggie's advice on diet highlights protein (though the American diet is currently believed to contain much more protein than needed), potassium again (lack of which causes constipation?), and calcium and magnesium (deficiencies of these purportedly can cause ""monthly or constant nervousness and irritability""). Finally, she offers some pointers on doctors and medications; but all of this--medical advice, nutrition, and area-specific exercise--is done better elsewhere. (See especially Martin & Tenenbaum, Diet Against Disease and Corbin, Nutrition--plus the ever-reliable Bonnie Prudden.) But Maggie's TV following will doubtless be inquiring--regardless.