Safety Of Very Low-calorie Diets

A very low-calorie diet is a treatment plan for seriously overweight people or severe obesity. Although minor side effects from a very low-calorie diet, or VLCD, commonly include fatigue, constipation, nausea and diarrhea, these conditions usually improve within a few weeks. However, safety concerns exist with VLCDs that involve potentially lethal consequences, so it is important to be under a physician's care if considering such a diet.

Identification

A very low-calorie diet is an aggressive weight-loss plan that allows 800 calories or less a day and usually involves doctor supervision, says the Weight--Control Information Network. A VLCD often uses commercially-prepared formulas, such as liquid shakes or bars, to promote rapid weight loss. These formulas should contain adequate levels of nutrition. Some physicians prescribe lean protein foods, such as fish and chicken, in addition to the supplements. The length of the diet should not exceed six months. The Diet Channel reported that participants lost 3 to 5 lbs. per week, a total of about 50 lbs. in 12 weeks.

Diabetes

Before considering a VLCD, it is important to undergo a thorough examination by a physician to ensure you do not have preexisting medical conditions which could worsen with a calorie-reduced diet. Of particular concern is the effect very low-calorie diets may have on inducing diabetes. The metabolic response to extremely low-calorie diets may be comparable to starvation, causing increased insulin resistance and anorexia nervosa. "The Journal of Diabetes and its Complications" published a report on a 1992 study conducted by the Tel-Aviv University Medical Center, Ichilov Hospital, Israel that observed the development of non-insulin-dependent diabetes mellitus in five out of seven patients on a strenuous low-calorie weight-reduction program. An additional two cases of insulin-dependent diabetes also resulted from the very low-calorie diet.

Cardiovascular Complications

Weight loss from very low-calorie diets in severely obese people has been associated with sudden death from ventricular arrhythmias. Major or rapid weight loss may damage the heart by decreasing muscle fiber size. In addition, deficiencies of protein, electrolytes and micro-nutrients, such as copper, magnesium and potassium, may contribute to a myofibrillar damage. "The American Journal of Clinical Nutrition" reported the findings of a 1992 study by Janis S Fisler suggesting that weight loss from very low-calorie diets provoked electrocardiogram abnormalities and precipitated acute and fatal arrhythmias in the obese subjects studied.

Gastrointestinal Problems

Very low-calorie diets have been shown to affect gastrointestinal and cardiac organ systems. A 1988 study by Eleanor A Young, Ph.D., RD/LD used rats divided into two groups, one of which was fed a low-calorie diet with 23 percent total calories from protein, carbohydrate and fat. Final weights of total body, the liver, small intestines and heart were lower in the diet group and revealed a protein depletion of the gastrointestinal system with a decrease in body nitrogen stores, specifically cardiac muscle, as published in "The American Journal of Clinical Nutrition."

Gallbladder Stones

Gallstones, which often develop in obese people, are most common after rapid weight loss. Weight loss may increase cholesterol levels in the gallbladder, which inhibit its ability to contract and expel bile. There may be a correlation with fat intake and gallstone formation as investigated in a 1998 study published in "Digestive Diseases and Sciences" using 272 moderately obese subjects with normal gallbladders who were given 900-calorie per day liquid diets for 13 weeks. The findings were that 17 percent of the group eating 16 g of fat daily developed stones with a weight loss of 18 kg , and 11.2 percent of the group eating 30 g of fat daily developed stones with similar weight loss. The experiment showed that substantial fat for rapid weight-reducing diets resulted in gallstone formation.