I've had limited experience with Ketamine. I was given the drug during procedures I was undergoing. So I never had the drug without being under doctor supervision and only for the limited time of the procedure.
From what I know about Ketamine it is an anesthetic and a dissociative drug. And as with all drugs can have side effects including weight loss and weight gain.
I'm not a doctor so getting medical advice is a great idea. Please be careful and I wish you the best.