When a person is extremely obese, a physician may prescribe a medically monitored weight loss program that will usually involve replacing solid foods with a liquid substitute.
The liquid substitute will usually supply between 500 and 800 calories each day, which means that it qualifies as a very low calorie diet.
The liquid substitute will also supply all of the necessary vitamins and minerals that would normally be provided by solid food.
Typically the liquid substitute comes in the form of a shake. Patients are told to drink a certain number of shakes every day, rather than eating, and to use that time period to break with old eating habits.
After a number of weeks of rapid weight loss and frequent meetings with a physician, who monitors the health and progress of the patient, solid foods may be slowly reintroduced.
The entire process is difficult and risky. It should only be undertaken when prescribed by a physician and it must be monitored by a medical professional! .
Usually, this sort of liquid diet is only prescribed when serious health risks, caused by obesity, outweigh any risks from the program.
One popular medically observed liquid diet is called Optifast. It is produced by the Swiss company, Novartis Medical Nutrition Corporation, that is also known for making Gerber baby food.
They report that, in a study of 20,000 people who used the Optifast program for 22 weeks, the average person lost 52 pounds and decreased their blood pressure by 10 percent.
The Optifast system is extremely expensive and not intended for the typical dieter.
