If a festoon was caused by weight gain, can it be reversed with weight loss?

Thanks for your question.   As we age and everything begins to drop, festooning can occur around your eye muscle.  Gaining and losing weight can draw more attention to these changes, but changing your weight again to compensate in the other direction does not necessarily remedy the situation.  If your condition is more severe, a lower blepharoplasty or lower eyelid lift would be recommended.  If it is not too severe, filler such as restylane would be an alternative for you.  Make sure you see a board certified plastic surgeon with much experience in both eye surgery and in injecting under the eye area.  Best of luck.