Very Low-Calorie Diets: NIDDK
Article title: Very Low-Calorie Diets: NIDDK
Obesity affects up to one-fourth of adult Americans,
increasing risk of death from diseases like diabetes, high blood pressure,
and heart disease. Traditional weight loss methods include low-calorie
diets between 800 to 1,500 calories a day and regular exercise. An
alternative method sometimes considered for bringing about significant
short-term weight loss in moderately to severely obese people is the very
low-calorie diet (VLCD).
What is a Very Low-Calorie Diet
VLCDs are commercially prepared formulas of 800
calories or less that replace all usual food intake. VLCDs are not the
same as over-the-counter meal replacements, which are meant to be
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.
Who Should Use a VLCD?
VLCDs are generally safe when used under proper
medical supervision in patients with a body mass index (BMI) greater than
30. BMI is a mathematical formula that takes into account both a person's
height and weight. To calculate BMI, a person's weight in kilograms is
divided by height in meters squared. 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 recommended for pregnant women
or breastfeeding women. VLCDs are not appropriate for children or
adolescents, except in specialized treatment programs.
Very little information exists regarding the usage of VLCDs in older
individuals. Because individuals over 50 already experience normal
depletion of lean body mass, use of a VLCD may not be warranted.
Additionally, persons over 50 may not tolerate the side effects associated
with VLCDs because of preexisting medical conditions or need for other
medications. Therefore, a physician, on a case by case basis, must
evaluate increased risks and potential benefits of drastic weight loss in
older individuals. Additionally, people with significant medical problems
or who are on medications may be able to use a VLCD, but this too must be
determined on an individual basis by a physician.
Health Benefits Associated With a
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.
Adverse Effects Associated With a
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 often develop in
obese people, anyway, (especially women), are even more common during
rapid weight loss. Some research indicates 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. Although VLCDs are efficient for
short-term weight loss, they are no more effective than other dietary
treatments in the long-term maintenance of reduced weight. 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 because
without a long-term commitment, their body weights will drift back up the
Endnote: This e-text is a modified version of a previously
published review article on very low-calorie diets, appearing in the
August 25, 1993, issue of the Journal of the American Medical
Association. Both the review article and this e-text were developed
with the advice of the National Task Force on the Prevention and Treatment
of Obesity, a subcommittee of the National Digestive Diseases Advisory
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NIH Publication No. 95-3894
e-text last updated: 9 February 1998