The Happy Juicer website defines a low calorie diet as a diet that contains between 900 and 1,300 calories a day. A very low calorie diet has no more than 800 calories per day. Typically a very low calorie diet is for obese individuals on a short-term basis and monitored by a physician. It is necessary to be under a doctor's supervision as low calorie diets lack in nutrition and can have negative side effects such as fatigue, constipation, nausea, diarrhea and the formation of gallstones, according to the National Institute of Diabetes and Digestive and Kidney Diseases. A low calorie diet is made for jump starting a change in lifestyle; if eating habits do not change, weight gain can occur.
Metabolism
Restrictive diets tend to decrease the basal metabolic rate in people. A study published in the 1987 issue of the American Journal of Clinical Nutrition was conducted over a six month period to determine the effects of a low calorie diet and energy expenditure and resting metabolic rate. The 15 women who participated in the study had a reduction in basal metabolic rate in the last three months as well as a decrease in energy expenditure. Another study published in the 1991 issue of the American Journal of Clinical Nutrition showed that the participants had a significant decrease in resting metabolic rate in the last two weeks of the three week study. Both studies found that the women had a decrease in weight loss in the last half of the studies as well.
Gallstones
According to the University of Maryland Medical Center, being overweight and rapidly losing weight can lead to formation of gallstones. Weight loss and weight cycling, defined as dieting and then putting the weight back on, increase the production of cholesterol in the liver, causing supersaturation and leading to gallstones. The risk for gallstones is highest, as high as 12 percent, with people who follow a low or very low calorie diet. It is also a high risk for those who lose more than 24 percent of their weight or 3.3 lb. a week.
Cardiac Dysfunction
According to the American Journal of Clinical Nutrition, 17 obese but healthy adults died suddenly of ventricular arrhythmias either during or after a rapid, massive weight loss from very low calorie diets in 1977 and 1978. An article reexamining this occurrence published in the 1984 issue of the American Journal of Clinical Nutrition confirms the 17 deaths were related to protein depletion involving the heart, thus leading to cardiac dysfunction due to low calorie diets. In a 1992 issue of this journal, a review of cardiac effects from low calorie diets reports that rapid or major weight loss damages the heart by decreasing myocardial fiber size. Contributing to this damage is lack of protein, electrolytes and micronutrients caused by a low calorie diet.
References
- American Journal of Clinical Nutrition: Energy-Metabolism Adaptation in Obese Adults on a Very-Low-Calorie Diet
- American Journal of Clinical Nutrition: Effect of a High-Protein, Very-Low-Calorie Diet on Resting Metabolism, Thyroid Hormones, and Energy Expenditure of Obese Middle-Aged Women
- American Journal of Clinical Nutrition: Cardiac Effects of Starvation and Semistarvation Diets: Safety and Mechanisms of Action
- American Journal of Clinical Nutrition: Cardiac Dysfunction in Obese Dieters: A Potentially Lethal Complication of Rapid, Massive Weight Loss
- National Institute of Diabetes and Digestive and Kidney Diseases: National Institutes of Health: Weight-control Information Network: Very Low Calorie Diets
Member Comments