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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intake the more rapid the weight loss, because the energy withdrawn from body fat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

therapy [30].

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.

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