A very low-calorie diet (VLCD) is a doctor-supervised diet that typically uses commercially prepared formulas to promote rapid weight loss in patients who are obese. These formulas, usually liquid shakes or bars, replace all food intake for several weeks or months. They are designed to produce rapid weight loss at the start of a weight-loss program in patients with a body mass index (BMI) greater than 30 and significant co-morbidities. BMI correlates significantly with total body fat content.
VLCD formulas need to contain appropriate levels of vitamins and micronutrients to ensure that patients meet their nutritional requirements. Some physicians also prescribe very low-calorie diets made up almost entirely of lean protein foods, such as fish and chicken. People on a VLCD consume about 800 calories per day or less. A very low-calorie diet may allow a patient who is moderately to extremely obese 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 rapidly improve obesity-related medical conditions, including diabetes, high blood pressure, and high cholesterol.
The rapid weight loss experienced by most people on a VLCD can be very motivating. Patients who participate in a very low-calorie diet program that includes lifestyle treatment typically lose about 15 to 25 percent of their initial weight during the first 3 to 6 months. They may maintain a 5-percent weight loss after 4 years if they adopt a healthy eating plan and physical activity habits.
Doctors must evaluate on a case-by-case basis the potential risks and benefits of rapid weight loss in older adults, as well as in patients who have significant medical problems or are on medications. A very low-calorie diet is certainly not for everyone.