amitriptyline and weight gain::I started with 10 mg and then moved up to 25 mg after 4 weeks amitriptyline and weight gain

amitriptyline and weight gain::I started with 10 mg and then moved up to 25 mg after 4 weeks.
For my back pain, it is a miracle drug.
I have 2 herniated discs in my low back and 2 in my neck.
That being said, i have gained alot of weight and i am disgusted with myself.
I started at 141 and i am up to 156.
I never feel full and i constantly graze.
I talked to my doc about it and he said that i have to decide whether or not i want to benefits of no back pain and watch diet and exercise or have back pain and drop a few pounds.
That was two months ago and at the time i went with no back pain.
Well, last night i decided that i am done with the amitriptyline.
I need to shed 20 pounds before summer.