A friend of mine has oviously brought her metabolism into starvation mode by performing strict low-calorie diets (without any exercise) and the following yoyo effect over now more than ten years. She can hardly eat more calories than her basal metabolic rate without gaining weight, so the next diet is just a matter of weeks.

How to break this vicious circle of dieting and gaining weight again after eating normal and bring her metabolism out of starvation mode?