This simply cannot work. If it does, that would imply that a short term dietary intervention would result in long term metabolic changes. More specifically, if one were to become able to maintain the new lower weight on the same caloric intake and macro nutrient composition that previously maintained a higher bodyweight, that necessarily requires either a) a higher energy expenditure, or b) less efficient assimilation of nutrients. Irrespective of which is the case, it also requires that there is no compensatory change in appetite to induce you to eat more. And all of this would be brought about by eating only [fill in your favourite short term dietary intervention details here] for a few days.
I really wish metabolism worked this way ... it would make things much easier.