By Janice Chilton  N.D. M.S

What is a Very Low-Calorie Diet (VLCD)?
VLCDs are not to be confused with the over-the-counter meal replacements which you can use to replace one or two meals a day.

VLCDs are commercially prepared formulas of 800 calories or less that replace all usual food intake. Under proper medical supervision they can effectively produce significant short-term weight loss in moderately obese patients. 

Since up to 25% of adult Americans are considered obese, it means that 1 in 4 
of our adult population is at increased risk of premature death from diabetes, heart disease and high blood pressure.

Typical weight loss remedies would include regular exercise and a low calorie diet of 800 -1,500 calories a day. In certain cases a very low-calorie diet (VLCD) is 
used to achieve accelerated short-term weight loss.

Is A VLCD right for you?
When used under proper medical supervision, VLCDs are generally safe in patients with a body mass index (BMI) greater than 30. 

Body mass index, or BMI, is a new term to most people. However, it is the measurement of choice for many physicians and researchers studying obesity.

BMI uses a mathematical formula that takes into account both your height and weight. Your BMI is your weight (in kilograms) divided by height (in meters) squared. (BMI = kg/m2).

Don’t be daunted by this. Here's an easy-to-use automatic BMI calculator.

In patients with a BMI of 27 to 30 VLCD's should only be used if you suffer from medical complications due to yourr obesity. VLCDs are not recommended for pregnant women or breastfeeding women. Nor are they appropriate for children or adolescents, except in specialized treatment programs.

Very little information exists regarding the usage of VLCDs in older individuals.
If you are over 50 you may not be able to tolerate the side effects from a VLCD because of some preexisting medical condition or your need for other medications. Also at 50 and over, you already experience normal depletion of lean body mass, so a VLCD may be risky. 

You should consult your physician since evaluations are on a case by case basis. Even if you're on medications, your physician may still be able to approve it. Drastic weight-loss is not recommended at any age. However, the risks do increase exponentially as you grow older.

Benefits
If you are severely to moderately obese you could lose about 3 to 5 pounds per week on a VLCD, for an average total weight loss of 44 pounds over 12 weeks. 

Even this small 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. 

Down Side
Many patients on a VLCD for 4 to 16 weeks report side effects such as fatigue, constipation, nausea, and diarrhea. 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 don't "hold" in the long-term maintenance of reduced weight. Therefore, obese patients should be encouraged to commit to a long-term treatment program. Ideally that would  include permanent lifestyle changes such as

1. healthier eating, 
2. regular physical activity, 
3. an improved attitude towards food.

The most effective method for weight-loss and weight control that I've come across is a drugless program developed by a medical physician. What impresses me is the unusually high daily calorie intake (2300-3500) for a weight loss program. Nevertheless, the results are speedy but not so fast as to be conducive to gallstones. You can read more about it here.