Question is wether there is a difference between different forms of B1

TTFD is pretty potent, but generallys we need less of it because absorption

Is there any specific reason for Thiamine HCL over TTFD or benfothiamine?

Additionally, of course weight, how you respond to food generally (feel like the best "test" is just how you feel), does your skin/ hair/ nails change?

Maybe do the Achilles Tendon Test to see wether reflexes get faster (sign T3 is doing its job)

For supplements, Mg is resposnbile for turning on over 5700 proteins, this is heck of a lot

Thyroid is responsible for literally anything, as it is critical in energy & energy is king, hence Mg to basically support your body for anything to come

B Vitamins, carbs, selenium, zinc are good things, but you don't need to supplement those when eating animal stuff

Thiamine or TTFD might be good tho to burn carbs off a lot more (works wonders pre workout for me)

Would also watch for root cause issues when you dialed in NDT dosage (mold is a huge one here, but also stealth infections & trauma)