Hello and welcome to Healthcare Magic. Thanks for your query.
Unexplained weight gain can be due to several causes - most commonly endocrine causes like hypothyroidism
, etc. Often, smokers who quit experience some amount of weight gain in the firt 1 to 2 months after quitting.
It is good that you are exercising regularly and I hope you maintain a regular exercise regimen in the future also. However, I would advise you to have a detailed medical evaluation done in order to rule out any medical causes for the unexplained weight gain.
Wish you all the best.
Dr. Jonas Sundarakumar