Crash diets are not suited to long-term weight loss, a German nutritionist is warning. Georg Abel, a professor at the University of Applied Sciences in Saarbruecken, says a sharp reduction in calorie intake initially causes the body to burn its stores of carbohydrate glycogen, which is accompanied by water loss. Body fat isn't significantly affected.
Although this results in rapid weight loss, the dieter rapidly regains it - and usually more - when previous eating habits are resumed, because the body has gone into starvation mode and slowed the speed at which it burns calories. An adult's daily energy requirement is about 2,000 calories. Crash diets typically cut calories to about 500 to 800 a day.
Abel said in a note that crash dieting frequently or for a long time could disrupt the body's natural regulation of hunger and satiation, as well as cause energy or nutritional deficiencies.