I was hooked on Diet Coke for a few years, and my bloodwork showed possible hypothyroidism. Of course the doctor wanted to put me on thyroid immediately even though the TSH count was only slightly abnormal. I told him I wanted to wait and see if any dietary changes would help. He said it wouldn't make a difference. I changed doctors, cut out all artificial sweeteners and other junk, started working out and eating better. Next blood panel showed perfectly normal thyroid counts.