Material has long appeared in magazines, newspapers and TV about what some consider to be the appalling eating and exercising habits of American children and teenagers--irregular meals, heavy ""snacks"" and hours of sedentary tube watching. More recent is a rapidly heating controversy about common methods of baby feeding: is the American infant stuffed beyond his needs; are solid foods being introduced too early? Dr. Eden says yes, as one corollary to his general theme: fat babies and children produce fat, unhealthy adults. Among his major recommendations covering pre-natal to teenage regimens: a pediatrician's monitoring of the baby's weight gain should be your guide, so don't feed the baby more than he requires (if he's piggish, dilute the milk; if he fusses, use a pacifier; milk, by the way, is the only food necessary in the first three months). ""Fat-proof' your household by not allowing junk foods; go easy on sugar, salt, high-cholesterol items and starches. And encourage exercise, preferably of the kind which may still be viable in middle age (biking, swimming, etc.). Certainly a beneficial program, although sparse in hard, supportive facts and documentation--one could wish for the source of such statements as ""Studies have shown that breast-fed babies end up on the average less fat than those who were bottle fed"" (Dr. Eden is, however, neutral on this matter); and the whole subject of milk (the incidence of allergies in infants, nutritive variety in commercial products and whether the ""perfect food"" sermonette in hygiene classes is a myth) needs more exploration. A closing chapter addresses teenagers worried about weight. A bit watered, but basically sound.