Medifast Diet Dangers

Medifast, a diet plan that relies on meal replacement shakes, soups, simple meals and bars for most of its daily calorie intake, promises quick and easy weight loss of up to 20 lbs. in 30 days on its website. Once available only as a medically-supervised liquid diet, Medifast now offers more choice in foods and the chance to eat one real meal containing lean meat and green vegetables each day in addition to five portion-controlled servings of Medifast products. A low-calorie, low-fat diet like Medifast is best followed under medical supervision, since it can cause health problems.

Rapid Weight Loss

Strictly following the Medifast plan supplies you with between 800 and 1,000 calories a day, making this a very low-calorie diet. Medifast shakes contain 90 calories each, according to the Medifast website, so five per day would supply 450 calories. A meal of lean meat and green vegetables would add no more than 500 calories for a total of 950 calories per day. Just 5 oz. of lean turkey contains only 212 calories. Very low-calorie diets do cause rapid weight loss, at least until your metabolism slows down to conserve energy. Rapid weight loss also often includes muscle loss in addition to fat loss, which slows your metabolism. Rapid weight loss can also cause gallbladder problems. In the long run, low calorie diets also interfere with your body's hunger and fullness signals, which can result in overeating when the diet ends, Go Ask Alice explains.

No Change in Eating Habits

Eating or drinking Medifast products five times a day teaches you nothing about controlling or modifying your eating habits. Once you stop using the product, odds are that you'll regain all the weight you lost and possibly more. Studies show that at best, around 20 percent of dieters who lose 10 percent of more of their total weight keep it off, R.R. Wing of Brown University reported in the 2001 "Annual Review of Nutrition."

Very Low Fat

Medifast supplies very little fat, 1 g per meal replacement shake, or around 5 g per day plus the fat from a five to seven oz. serving of lean meat. Some fat is essential in your diet. Without adequate fat, women may stop menstruating and hair may turn dull and lifeless and fall out. Skin may also become dull looking. Fat is essential for absorption of fat-soluble vitamins A, D, E and K. Fat-soluble vitamin deficiencies can cause anemia, low red blood cell production, bone loss from decreased calcium intake and increased bleeding tendencies. Very low-fat diet may increase the risk of hemorrhagic stroke, the University of Maryland Medical Center warns.