is thyroid replacement therapy based on weight, and if I lose weight, will it effect my dose?

is thyroid replacement therapy based on weight,
and if I lose weight, will it effect my dose?

I had a thyriodectomy 13 years ago and am now on total replacement and stable (after having children) but have gained about 20 pounds. If I lose the weight, will my dose need to be adjusted?
How can I lose safely. I feel fantastic on 175mgrams with
Levothyroxine-generic.