Please try to get the test result info and reference ranges from the doctor, and post here. Without that info, it will be difficult to give you anything other than the following general answers. Dosage changes as one ages would probably be dependent on whether the doctor was medicating a patient based on symptoms, or based on test results. In general a lowered dose would be expected to reduce metabolism and thereby contribute to weight gain. A lot depends on how much meds are reduced.
My thyroid lab test was a routine check I usually get every 2 years or so when I get a physical. The past lowering of medication was done because the thought was higher levels were leaching calcium from my bones. I have ostopenia but I have managed to increase my bone density due to exercise, I take no other meds other than thyroid. My arms and legs are ridiculously skinny, but I look like I am pregnant. I carry all my weight in the tummy. I'm 5'6 and weigh 133. I am active, do Zumba 2 times a week for the last few years, and walk everyday. It's definitely a concern for me if I gain weight because I know I won't gain it anywhere but the abdomen, and I surely don't want that. I really don't know my numbers on the test.
Do you know if you have autoimmune thyroid condition? Such as Hashimoto's?
Like gimel, I'd be interested in seeing what your actual thyroid levels are, and what your doctor is basing the dosage change on .
i have survived thyroid cancer and have had the right side of mine removed last year. the lower your levels are, the slower your metabolism is so you usually will gain weight. however, the higher the level, the higher the metabolism which can lead to heart palpitations and other problems. my personal experience has been that my own thyroid levels did fluctuate frequently even on various doses of medication. however since the right side was removed, i have managed to stay on the same dose for about a year now.
What tests or symptoms prompted your doctor to lower your meds? Please post your thyroid test results and reference ranges shown on the lab report.