Physicians may prescribe and supervise a very-low calorie diet, or VLCD, consisting of 800 or fewer calories a day for morbidly obese patients. Controversy exists as to the long-term efficicacy of such a regimen, which is functionally equivalent to starvation in that people on VLCDs stop experiencing hunger after four or five days. The diet can have effects both beneficial and detrimental.
Glycemic and Lipid Profile
Short-term VLCDs are often prescribed to Type II diabetics with poor glycemic, or blood sugar, control. Endocrinologist Robert R. Henry and colleagues found in 1986 that obese diabetics placed on a 300-calorie-a-day diet for five weeks experienced rapid improvement in blood glucose levels and that both diabetics and non-diabetic obese participants demonstrated a significant lowering of both triglycerides and cholesterol, both of which are circulating forms of fat. As expected, both diabetic and non-diabetic subjects lost large amounts of weight, an average of about 24 lbs. in the former group and 36 lbs. in the latter.
Anti-Aging Effects
Extreme calorie restriction has been found to slow certain processes associating with aging, an effect presumably mediated through the depression of metabolic rate. Research has shown that the life spans of some animals are extended after calorie restriction initiated later in life. VLCDs can reduce damage to protective telomeres, which are parts of chromosomes. This is turn this reduces the damaging oxidation of tissue, which under ordinary circumstances is associated with various age-related diseases. This research did not directly resolve any questions concerning the effect of VLCDs in human beings, and research continues in this vein.
Gallstones
One consistent adverse finding in VLCD patients, especially women, is gallstone formation. Gastroenterologist Rodger A. Liddle and colleagues in 1989 followed dieting and non-dieting obese subjects for eight weeks and found that more than one-fourth of the dieting subjects had developed gallstones during this period, whereas none of the control subjects had. This effect is believed to result from a decrease in the ability of the gallbladder to discharge bile and cholesterol during periods of rapid, such as 3 to 5 lbs. pounds per week, weight loss, and may be offset with the use of certain medications.
References
- Diabetes: Metabolic Consequences of Very-low-calorie Diet Therapy in Obese Non-insulin-dependent Diabetic and Nondiabetic Subjects
- Science Daily: Insight Into Why Low Calorie Diet Can Extend Lifespan--Even If Adopted Later in Life
- Archives of Internal Medicine: Gallstone Formation During Weight-Reduction Dieting
- National Institute of Diabetes and Digestive and Kidney Diseases -- Weight-control Information Network: Very Low-calorie Diets
- UCLA Center for Human Nutrition: Dietary Programs / Very Low Calorie Diet (VLCD)
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