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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 (VLCD)?
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 VLCD
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 VLCD
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.
Conclusion
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
scale.
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