Answer option C is your most likely answer. Fad diets are as stated merely fads that have strung up to provide easy weight loss solutions as quickly as possible. Unfortunately many of these strategies are not safe or have been backed up by Healthcare experts. Additionally these diets are not used consistently, usually bringing weight down to an accepted level in the opinion of the person using the diet, before the discontinue, and because the diets are usually skimping on important nutrition the body will actually try and bring more weight in order to prep for possible future malnourishment.
Hope this helps, and if you got any other questions on the topic feel free to ask.
