The optimal management of overweight and obesity requires acombination of diet, exercise, and behavioral modification
GOALS OF WEIGHT LOSS — It is important to set goals when discussing a dietary
weight loss program with an individual patient. An initial weight loss goal of 5 to 7
percent of body weight is realistic for most individuals.
The first goal for any overweight individual is to prevent further weight gain and
keep body weight stable (within 5 percent of its current level).
Most patients have a weight loss goal of 30 percent or morebelow current weight, which is well in excess of realistic levels
Loss of 5 to 7 percent of initial body weight and maintenance of this loss is a good
medical result, even if the subject does not reach his or her "dream" weight.
An averagedeficit of 500 kcal/day should result in weight loss of approximately 0.5 kg/week (1 lb/week).
Very low-calorie diets — Diets with energy levels between 200 and 800 kcal/day
are called "very low-calorie diets," while those below 200 kcal/day can be termed
starvation diets. The basis for these diets was the notion that the lower the calorie
intake the more rapid the weight loss, because the energy withdrawn from body fat
stores is a function of the energy deficit. Starvation is the ultimate very low calorie diet
and results in the most rapid weight loss. Although once popular, starvation diets are
now rarely used for treatment of obesity.
Very-low calorie diets have not been shown to be superior to conventional diets for
long-term weight loss. In a meta-analysis of six trials comparing very low-calorie diets
with conventional low-calorie diets, short-term weight loss was greater with very
low-calorie diets (16.1 versus 9.7 versus percent of initial weight), but there was no
difference in long-term weight loss (6.3 versus 5.0 percent) [ 29].
As with all diets, very low-calorie diets initially result in substantial protein loss that
diminishes with time. Other expected effects include reduction in blood pressure and
improvement in hyperglycemia in diabetic patients.
Subjects adhering to very low-calorie diets usually have a fall in blood pressure,
especially during the first week. Antihypertensive drugs, especially calcium
channel blockers and diuretics, should usually be discontinued when a very low
calorie diet is begun unless moderate to severe hypertension is present.
Most diabetic patients eating very low-calorie diets have marked improvement in
hyperglycemia. Blood glucose concentrations fall within the first one to two weeks,
and remain lower as long as the diet is continued. Those patients taking less than
50 units of insulin or an oral hypoglycemic drug will usually be able to discontinue
The side effects of very low-calorie diets include hair loss, thinning of the skin, and
coldness. These diets are contraindicated for lactating and pregnant women, and in
children who require protein for linear growth. As with all diets, there is increased
cholesterol mobilization from peripheral fat stores, thus increasing the risk of gallstones
Very low-calorie diets should be reserved for subjects who require rapid weight loss
for a specific purpose such as surgery. The weight regain when the diet is stopped is
often rapid, and it is better to take a more sustainable approach than to use a method
that cannot be sustained.