If you don't want to replace a pill with a pill... then as said move and diet.

If you are on T3 as a doctor therapy..then I suspect your thyroid does not work properly?

Ask your doctor about metformin. It will not replace the T3 but it will surpress appetite and is the one drug on the market that I feel everyone should take. Nothing but a great supplement for many aspects of the body. It is not a profit item. I get a kilo for about 50 USD in powder form.

Good Luck