Is gaining weight by drinking water and then reducing it to win a higher percentage in a weight loss competition considered cheating?

The purpose of the competition is weight loss through the reduction of fats and lipids, which positively impacts health and activity. The expulsion of bodily fluids is not included unless authorized by the organizers. It is permissible to accept a prize for it, as it is among the beneficial matters that bring health and vitality to the participant, and this is a legitimate, recognized objective. This competition is a form of physical strength preparation, and it is like horsemanship in that it achieves a legitimate objective.