Effective for short-term weight-loss by controlling calorie intake, liquid diets are not intended for long periods of time. "When you drastically reduce the amount of calories you consume, your metabolism slows to conserve energy. Unless you change your eating habits, you'll gain back the weight as soon as you return to your old diet," according to WebMD. Former Massachusetts House Speaker George Keverian, who famously went on a 55-week liquid diet in which he lost 255 pounds, learned that the hard way. By 1990, he had gained the weight back and since has had a lifelong struggle with his weight. Keverian had gastric bypass surgery in June 2002. Here, he is pictured having his first real meal in March 1981 after the 55 weeks on the liquid diet.