Yup. I developed Hashimoto's back in the 1990s, possibly earlier (probably due to an unusual bad reaction to gamma globulin -- I used to work in hemodialysis with patients who had hepatitis). I started taking low dose thyroid meds in the early 2000s. By 2017 I had thyroid cancer. After surgery my levothyroxine dose was gradually increased to 112mcg (yeah, unusually specific, but my endocrinologist is very conservative and will authorize increases only every 3-6 months -- and everything is delayed now due to the pandemic).

I feel like it needs to be increased but I know the doc wants me to wait until my autumn 2020 appointment. They're also concerned by premature bone density loss, and the thyroid, parathyroid, etc,. are all interconnected.

My optimal weight when I was in my 20s was around 145, and still would be (I'm 62). In the early 2000s in my worst health phase I got up to 205 lbs. My back and neck were broken in a 2001 car wreck so I was unable to do any serious exercise for years. I resumed cycling in 2015 and gradually lost weight. By 2017 I was down to 160.

In 2018 I cut way back on carbs and sugars, mostly eliminating beer (I might have one a month now) and junk foods. I did some fasting exercise -- very easy sessions on the indoor trainer or very casual paced rides around the neighborhood for 60-90 minutes.

I'm down to 147 lbs now, with just a bit of belly fat.

To be honest, I'm not sure it's worth the hassle. I don't feel any better or stronger. I'm not faster on the bike. I'm going to start adding carbs back to the diet and see how it goes. I love pizza and beer, so I'll add that once a week (well, pizza usually lasts a couple of days, including for breakfast). I might eat a bit more during my 50+ mile rides. Sometimes I eat only one Clif bar and a couple of gels during long rides. I probably should consume a bit more.

Anyway, don't do anything too quickly, no crash diets, etc. Feeling hungry all the time is a recipe for diet and exercise failure. Exercise and ride your bike for pleasure. Eat sensibly. Don't worry about specific weight goals.