Very Low Calorie Diet for obesity
A liquid based diet that is severely restrictive in
energy with an intake of
about 800 calories or less per day is considered a very low calorie diet. These
diets are an alternative method that moderately to severely
obese people may
consider for significant, short-term
weight loss. Such a diet are recommended
for a relatively short term (3-6 months) and are to be followed only under
Medical supervision is essential:
(a) To ensure only suitable candidates follow the
(b) To ensure
(c) To monitor progress.
Traditional weight loss methods include low-calorie diets
that allow between 800 to 1,500 calories a day and encourage regular
The average weight loss in this period of time is 10 lb(4.54 kg) to 12
lb(5.44 kg). If exercise is made part of the
weight-loss program, the average
weight loss increases to about 20 lb(9.07 kg).
Changes that take place within your body while you are on a VLCD
Slow down of
BMR - Your metabolism slows to conserve energy because the body
thinks it is starving.
Breakdown of protein as a source of energy
- To get needed
carbohydrate, the body breaks down
protein. This causes
a loss of lean body mass such as organ
and muscle tissue. It is important to preserve lean tissue, since it increases
your basal metabolic rate. Losing too much lean tissue increases the
percentage of fat in your body. The result is a
reduced metabolism. This is one reason why it is so easy to regain weight when
you lose weight quickly.
Fat loss - In a VLCD (or during starvation), about half the weight you lose
is fat and the other half is lean tissue, such as muscle. On a more moderate
diet, the loss is about 75% fat and 25% lean tissue.
Electrolyte and water loss - Electrolytes are minerals found naturally in
the body, such as
magnesium. Electrolytes are
needed to keep the body's balance of fluids at the proper level and to
maintain normal functions, such as heart rhythm, muscle contraction, and brain
function. Mineral and electrolyte imbalances can occur while on a VLCD. These
imbalances can be life-threatening. This is the reason these VLCDs must only
be used under a health professional's supervision.
Calcium Depletion -
Bone mass is lost. This is more risky for women,
because they diet more often than men and they are also at higher risk for
Who can benefit from a very low calorie diet
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. 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.
This does not include children, adolescents, pregnant or breast-feeding
women, for whom very low calorie diets are not appropriate unless part of a
specialized treatment program.
over 50 may not tolerate the side effects associated with VLCDs because of
preexisting medical conditions or need for other medications.
These diets are not recommended if
you have heart problems, blood clotting problems, bleeding ulcers, liver
disease, kidney disease, or
cancer or if you have had a stroke.
Benefits of 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
high blood pressure, and high cholesterol. Combining a VLCD with
behavioral therapy and exercise may also increase
weight loss and may slow
However, VLCDs are no more effective than more modest dietary restrictions in
the long-term maintenance of reduced weight.
Side Effects of VLCD
patients on a VLCD for 4 to 16 weeks report minor
side effects such as
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
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
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
regular physical activity, and an improved outlook about food because without a
long-term commitment, their body weights will drift back up the scale.