These beverages, known as liquid meal replacements, are fortified with vitamins and minerals and often have a good balance of carbohydrates, protein, and fat. But people shouldn't rely on them more than once or twice a week. Many of the drinks are high in sugar and lack a lot of the beneficial components of whole foods, such as fiber (though some manufacturers add it in) and the anticancer compounds known as phytochemicals.
Most of them also provide only about 250 calories -- roughly half the amount found in the average meal.
Although postpartum moms who are trying to shed baby pounds might find themselves tempted to try out these shakes, "they won't help you adopt new eating habits, which is what you have to do to lose weight and keep it off," says Sharon Miles, a nutritionist in Torrance, CA. .