I took phentermine with success as part of my physician monitored weight loss. I have to say it’s pretty hard core...it’s basically speed. Pros of the drug were that I had constant energy and I never felt hungry. The cons for me were excessive sweating, extremely dry mouth and insomnia. Now whenever I mention that I took phentermine to other physicians or nurses they always seem to cringe. If I were in your shoes I would try other options first like redoing pre-op. If all else fails and you’re still interested just make sure you’re very closely monitored by your doctor. Best wishes