VERY LOW CALORIE DIETS
These diets are also called VLCD (very low calorie diets). They were designed to achieve a greater and more rapid loss in weight than conventional diets, but without the inconvenience of a total fast. The intake is between 400-800 Kcal/day, being enriched by biologically high value proteins (0.8-1.5 g/Kg of weight/day), sufficient carbohydrates to not produce cetosis (80-100 g/day) and the minimum of essential fatty acids (10 g/day). They can be classified into two groups:
Formula diets: in a powder form to be instantly dissolved, done as an exclusive treatment or combined with other foods.
Food diets: cheaper but require vitamin and mineral supplements because of deficiencies.
The VLCD weight-loss program usually consists of various phases:
1. Conventional diet (1200-1500 Kcal.) for 1-4 weeks
2. A diet very low in calories for a period of no more than 4-8 weeks.
3. Progressive reintroduction of solid foods until a return to the conventional diet has been reached.
4. Maintenance of a conventional diet, making a special emphasis in the practice of physical exercise and conduct therapy.
On the short term, the weight lost is greater than that obtained by the conventional diet, presuming a 1.5-2.0 Kg/week in females and 2.0-2.5 Kg/Week in males. However, the long-term results do not demonstrate advantages when compared to conventional diets, with an observed rate of recuperation of lost weight at 40% in the first year.
VLCD is reserved as the last recourse in very motivated patients, with a BMI >30Kg/m2 that have not responded to other more conventional treatments, especially if a rapid weight loss is needed for medical problems or in preparation for surgery. There do exist, however, contraindications for the prescription of a VLCD.