Yo-Yo Dieting refers to a repeated cycle of weight loss and weight gain. The theory of Yo-Yo dieting is that owing to continually dieting your body adapts to the fewer calories and in response stores fat more readily - making it harder to lose weight.
Yo-Yo dieting is very common among those who try to lose weight. It is true that 95% of dieters fail to maintain weight loss over a five year period. However, many contest the above theory arguing that whilst on a strict diet the body a dieters RMR (resting metabolic weight) will drop when normal eating patterns are resumed the dieters RMR returns to normal.
What is agreed is that Yo-Yo Dieting is not good for us. Repeated weight fluctuations have been likened to many health problems including heart disease, secondary diabetes and gall bladder problems. Sudden weight loss can lead to a loss of lean tissue and nutritional deficiencies which will also have serious health implications.