You can lose between three and five pounds per week while on a complete liquid fast. While some dieters fast for a short time to lose a few pounds, others fast for weeks or months. Doctors supervise and closely monitor obese patients recommended for a liquid very low calorie diet (VLCD).
Very low calorie diets (VLCD) typically contain 800 to 1,000 calories per day in the form of liquids. Some plans include specially prepared bars as meal replacement in lieu of only liquids.
Patients on liquid diets do not use the diet drinks sold in grocery stores. Instead, doctors prescribe specially formulated products, such as Optifast, that contain adequate nutrients and the right number of calories.
Some side effects of liquid VLCDs include gallstones, fatigue, constipation, nausea or diarrhea. If needed, doctors provide medications to help manage symptoms.