I'm 77 And Have Been On Levothyroxine For About 40

I'm 77 and have been on levothyroxine for about 40 years, and recently found to have a high TSH. Being tapered down from mcg to 125 mcg. Have symptoms of coldness even in hot weather while in moderate air conditioning. Also, difficulty losing weight while on healthy diet (Weight Watchers). Gradual weight gain in past several years with no change in healthy diet. Is it true that older people need less thyroid replacement as they age?