Hypothyroidism and Exercise

[WWYD2016]

Hi guys. I need your opinion. I have for the last 7 years taken great care of my body through a combination of cardio and strength training and a balanced diet, I couldn't be happier with my physique.
I was upset to be recently diagnosed with Hypothyroidism.
I've heard weight increase to be an unavoidable side effect so have upped my exercise intensity and successfully upped my muscle mass, reduced my fat mass thus increasing my basal metabolic rate.
Good eh? No, if you believe what you read online.
Apparently strength and cardio training by nature damage the body forcing repair (catabolic), but is apparently harmful if you have Hypothyroidism.
WTF.
What are your thoughts?

I have hypothyroidism and have never gained any weight from it (which actually meant it took a while to get diagnosed). So, you shouldn’t assume weight gain is inevitable. If you haven’t personally experienced weight gain I wouldn’t worry about changing your exercise regime. Once your thyroid is well regulated with the right level of meds you should feel back to normal. It might take a while with your doctors fiddling with the dose to get the right level for you but try not to worry. And don’t spend too much time online. Lots of horror stories but can also feel perfectly normal and healthy with hypothyroidism.

Can you link to the studies ?

I’m hypo and was underweight for a long time.

I’m not Underweight now but still at lower end of bmi (21)

My Mum is hypo and she's tiny.