Traditional weight loss methods include low-calorie diets between 1,200 to 1,500 calories a day and regular exercise. However, an alternative method that moderately to severely obese people may consider for significant, short-term weight loss is the very low-calorie diet (VLCD).

Many VLCDs are commercially prepared formulas of 800 calories or less that replace all usual food intake. Others, such as the well-known grapefruit diet, rely on eating a lot of the same low-calorie food or foods. VLCDs are not the same as over-the-counter meal replacements, which are substituted for one or two meals a day. VLCDs, when used under proper medical supervision, effectively produce significant short-term weight loss in moderately to severely obese patients.

Are VLCDs harmful to my health?
VLCDs are generally safe when used under proper medical supervision in patients with a body mass index (BMI) greater than 30. Use of VLCDs in patients with a BMI of 27 to 30 should be reserved for those who have medical complications resulting from their obesity.

VLCDs are not suitable for everyone. Physicians generally recommend them on a case-by-case basis and your physician will decide whether or not such a diet is appropriate for your condition. VLCDs are not recommended for pregnant or breastfeeding women, and are not appropriate for children or adolescents, except in specialized treatment programs. Due to the need for other medications for preexisting conditions, as well as the possibility of side effects, these types of diets may not be suitable for patients over 50, either.

How effective are VLCDs?
A VLCD may allow a severely to moderately obese patient to lose about 3 to 5 pounds per week, for an average total weight loss of 44 pounds over 12 weeks. Such a weight loss can improve obesity-related medical conditions, including diabetes, high blood pressure and high cholesterol. Combining a VLCD with behavioral therapy and exercise may also increase weight loss and may slow weight regain. However, VLCDs are no more effective than more modest dietary restrictions in the long-term maintenance of reduced weight.

Many patients on a VLCD for 4 to 16 weeks report minor side effects such as fatigue, constipation, nausea and diarrhea, but these conditions usually improve within a few weeks and rarely prevent patients from completing the program.

The most common serious side effect seen with VLCDs is gallstone formation. Gallstones, which frequently develop in obese people (especially women), are even more common during rapid weight loss. The reason for this may be that rapid weight loss appears to decrease the gallbladder's ability to contract bile. But, it is unclear whether VLCDs directly cause gallstones or whether the amount of weight loss is responsible for the formation of gallstones.

For most obese individuals, obesity is a long-term condition that requires a lifetime of attention, even after a formal weight loss treatment ends. Therefore, obese patients should be encouraged to commit to a long-term treatment program that includes permanent lifestyle changes of healthier eating, regular physical activity and an improved outlook about food. By sticking to a long-term commitment, patients will prevent their weights from drifting back up the scale.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional written health information, please contact the Health Information Center at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771 or visit www.clevelandclinic.org/health/.

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