Very low calorie diet (VLCD) is a diet with very or extremely low daily food energy consumption. It is defined as a diet of 800 kilocalories (3,300 kJ) per day or less. VLCDs are formulated, nutritionally complete, liquid meals containing 800 kilocalories or less per day. VLCDs also contain the recommended daily requirements for vitamins, minerals, trace elements, fatty acids and protein. Carbohydrate may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. The VLCD products are usually a powder which is mixed with water or another low-food-energy liquid. The VLCD is prescribed on a case to case basis for rapid weight loss (about 1.5 to 2.5 kilograms or 3 to 5 pounds per week) in patients with Body Mass Index of 30 and above. The health care provider can recommend the diet to a patient with BMI between 27 and 30 if the medical complications the patient has due to overweight present serious health risk.