When on a VLCD, calories and carbohydrates are limited and the body burns its own storage fat for energy. The fat is released into the bloodstream, travels to the liver, and is converted to ketones. Ketones are then released back into the bloodstream and used for energy. Typical daily nutrition consumed by the patient is limited to 800 calories per day. One-hundred percent of the nutrition is provided by the protein supplement meal replacements used in the program.