Liquid diets can be a good way to jump-start your weight loss, because they are regimented and calorie controlled. You can drink almost any diet shake or diet drink that is on the market, as long as it has about 15 grams of protein per serving, and no more than 100 calories per serving. Most patients have 2 drinks, 2-3 times a day. Diet bars can offer the same structure for weight loss quick-start. You can eat almost any diet bar that is on the market, as long as it has about 15 grams of protein per serving, and no more than 150 calories per serving. Most patients eat 2 bars, 2-3 times a day. You will probably lose 5-10 pounds your first week on a bar or formula diet, and about 5 pounds every week thereafter.