I have been quit for one year now and was diagnosed with hypothyroidism last month. I had my levels checked three years ago during a pervious quit and no one called about the results so I thought they were fine. hypothyrpiodism slows your metabolism way down...causes weight gain, depression, brain fog, digestive issues, hair and skin problem, etc. Three years ago when I was trying to quit smoking, I was struggling I didn't feel better, I was depressed, tired irritable long after I should have felt better. I went back to smoking. Last year, when I quit I was struggling but pushed through, but by fall I had lost interest in everything, was gaining weight like crazy and just not getting anything done. I was dieting and exercising and getting nowhere. I had a checkup and mentioned the thyroid test, went for another and oh my goodness my levels were high! Normal range is .03 to 5 mine was 49, and found out that three years ago it was 19. I got to thinking that quitting smoking might have triggered this and some research seems top point in that direction. So if your have gotten through NML and still struggling it might be your thyroid, please hav it checked, especially if there is a family history of this condition. I thought Thomas might be able to shed some light on this since he reads a lot of research. No matter what, I am a happy non smoker.