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Very Low Calorie Diets (VLCD)
(2384 total words in this text)
(3033 Reads)
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&nbdp;
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Obesity
affects nearly one-third of adults in the United States, increasing their
risk for diabetes, high blood pressure, and heart disease. Traditional
weight loss methods include low-calorie diets from 800 to 1,500 calories
a day and regular physical activity. Health care providers sometimes consider
an alternative method for bringing about significant short-term weight
loss in patients who are moderately to extremely obese: the very-low-calorie
diet.
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VLCDs
are commercially prepared formulas of about 800 calories that replace
all usual food intake for several weeks or months. VLCDs are not the same
as over-the-counter meal replacements, which are meant to substitute for
one or two meals a day. VLCDs, when used under proper medical supervision,
effectively produce significant short-term weight loss in patients who
are moderately to extremely obese.
Studies
have shown that meal replacements at higher calorie levels (800 –
1000 calories) produce weight loss similar to that seen with much lower
calorie levels, probably due to better compliance with the diet. In addition,
VLCDs are usually part of weight-loss treatment programs that include
other techniques such as behavioral therapy, nutrition counseling, physical
activity, and/or drug treatment.
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VLCDs
are intended to produce rapid weight loss at the start of a weight-loss
program in patients with a body mass index (BMI) greater than 30. BMI
correlates significantly with total body fat content. It is calculated
by dividing weight in kilograms by height in meters squared, or by dividing
weight in pounds by height in inches squared and multiplying by 703.
Use
of VLCDs in patients with a BMI of 27 to 30 should be reserved for those
who have medical complications resulting from their overweight. VLCDs
are not recommended for pregnant or breastfeeding women. VLCDs are not
appropriate for children or adolescents, except in specialized treatment
programs.
Very
little information exists regarding the use of VLCDs in older people.
Because people over age 50 already experience normal depletion of lean
body mass, use of a VLCD may not be warranted. Also, people over 50
may not tolerate the side effects associated with VLCDs because of preexisting
medical conditions or need for other medications. Physicians must evaluate
on a case-by-case basis the potential risks and benefits of rapid weight
loss in older individuals, as well as in people with significant medical
problems or who are on medications.
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Health
benefits of a VLCD
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A
VLCD may allow a patient who is moderately to extremely obese 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 rapidly improve obesity-related
medical conditions, including diabetes, high blood pressure, and high
cholesterol.
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Adverse
effects of a VLCD
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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 is gallstone
formation. Gallstones, which often develop anyway in people who are
obese, especially women, are even more common during rapid weight loss.
Research indicates that rapid weight loss may increase cholesterol levels
in the gallbladder and decrease its ability to contract and expel bile.
The drug ursodiol can prevent gallstone formation during rapid weight
loss, but is not often used for this purpose.
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Maintaining
Weight Loss
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Studies
show that the long-term results of VLCDs vary widely, but weight regain
is common. Combining a VLCD with behavior therapy and physical activity
may help increase weight loss and slow weight regain. In the long term,
however, VLCDs are no more effective than more modest dietary restrictions.
For
most people who are obese, obesity is a long-term condition that requires
a lifetime of attention even after formal weight loss treatment ends.
Therefore, health care providers should encourage patients who are obese
to commit to permanent changes of healthier eating, regular physical activity,
and an improved outlook about food.
Endnote:
This fact sheet is an updated, modified version of a previously published
review article appearing in the August 25, 1993 issue of the Journal
of the American Medical Association. Both the review article and this
fact sheet were developed with the advice of the National Task Force on
Prevention and Treatment of Obesity.
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