Taking supplements while on a crash diet may give you vitamins and minerals, but not the proteins, fats and carbohydrates that muscles need to keep working, warns the California Dietetic Assn.
According to a recent study at the University of Toronto, after just two weeks of severely restricted calorie levels--400 calories a day, supplemented with vitamins and minerals--microscopic signs of atrophy set in as muscles prepared themselves for famine.
"We can consume all the vitamin and mineral supplements in the world, but without adequate calorie intake a person could starve to death," said registered dietitian Cheryl Loggins, CDA president.
In fact, Loggins said, a 400-calorie diet is not safe by any standards.
According to CDA, a body needs protein, dietary fat and carbohydrates as well as the 13 major vitamins and minerals plus trace elements to function properly. If an adequate balance of these nutrients is not consumed, even with a daily calorie level of at least 1,200 calories the result will be weak muscles and fatigue.