Some meal replacements are better than others. Meal replacements that provide a complete nutritional replacement of protein and vitamins and minerals normally consumed in foods will keep you full for a longer period of time and protect your muscles. Muscle loss can result in the so-called yo-yo effect of gaining back the weight that was lost (and sometimes even more). To avoid the yo-yo effect on a liquid diet, try a high-protein meal replacement such as Almased.