Very-low-calorie and low-calorie diets
The term very-low-calorie diet is used to describe diets supplying fewer than 800 calories a day. Typically, patients must replace food with a powdered supplement that is combined with a noncaloric liquid (water or diet soda). To prevent deficiencies, the supplement is primarily made of high-quality protein derived from milk, eggs, or soy, along with a small amount of carbohydrates, minimal fat, and added vitamins and minerals. The high protein content of these diets is essential to help preserve muscle mass when calorie intake is so low.
Recently, many centers modified their VLCD formulas to contain more calories. Studies have shown that weight loss is about as good on 800 as on 400 to 500 calories a day, and there are probably fewer risks. The term low-calorie diet is used to describe diets that supply from at least 800 calories per day to slightly below the person's daily caloric expenditure. So for a person needing 2,000 calories per day, a VLCD is up to 799 calories, and an LCD is 800 to 1,999 calories. (Although a program may be referred to as a low-calorie diet, or LCD, we will use VLCD to describe both types, except where the protocols differ.)
Typically lasting 12 to 16 weeks, VLCDs require close medical supervision and are usually administered by weight loss clinics or hospitals. Programs should include regular medical monitoring, behavioral counseling to help you adjust to the diet, and instruction for changing eating patterns once food is reintroduced. Programs may also provide classes and support groups; many place a great emphasis on exercise. Once the VLCD phase is completed, food is slowly reintroduced over two to 10 weeks. The cost of participation is around $2,000 to $3,000. Few insurance companies cover this cost.
VLCDs are appropriate for people with a body mass index of 35 or higher who have been unable to lose weight with conventional diet and exercise. LCDs are appropriate for individuals with a BMI between 30 and 34.9, especially for those who have coexisting conditions, such as type 2 diabetes, hypertension, high triglycerides, low HDL cholesterol, sleep apnea, or osteoarthritis.
Contraindications to VLCDs include a recent heart attack or stroke, heart rhythm abnormalities (arrhythmias), angina, liver or kidney disease, or type 1 diabetes. However, insulin-treated, obese patients with type 2 diabetes can benefit from VLCDs.
For people who can stay on them, VLCDs produce dramatic reductions in weight. On average, participants lose 2.5 to 4 pounds per week, at a rate that tends to slow as the duration of the VLCD increases to months.
Despite the dramatic success possible with VLCDs, they are not a panacea. About 25 percent of people who start a VLCD cannot adhere to the strict regimen and drop out of the program. Most of those who do complete treatment regain large amounts of weight within a year or two, typically reaching pretreatment weight within five years.
VLCD programs are worthless without detailed attention to long-term maintenance. You must learn to overcome the eating and behavioral patterns that contributed to your obesity in the first place--and you ultimately must make daily food choices on your own.
In general, VLCDs are safe when medically supervised. Early side effects of hunger, fatigue, and light-headedness usually subside within two weeks. People who cannot tolerate milk products may react to a dairy-based formula. Later on, dieters may note constipation and intolerance to cold, and the risk of gallstones is increased.
