I’m still trying to figure this out! I know that consistent exercise helps (for me it’s walking) and I did lose some weight when I went low carb but I don’t really know the science of what keeps people with low thyroid function from losing weight.

You could talk to your doctor about increasing your Synthroid dosage. Make sure if they do a blood test on you to test T3, T4, AND TSH. A lot of doctors don't test TSH and that could be out of balance even if T3 and T4 levels are normal with medication.

I went to a weight management run by endocrinologists. They assessed my body and metabolism. They also have a nutritionist I was working with. The nutritionist helped me with foods I was eating and how to have a balanced diet. Her suggestion is your plate should be 1/2 green leafy vegetable 1/4 grain and 1/4 protein. But even with changing my diet and exercising I was still not losing weight so they then moved on to medication management, and put me on phentermine(stimulant) for weight loss and it really help with appetite control and elevate energy levels. You can also try to get either your doctor to test your food sensitivities and how your body absorbs certain foods because everyone is different. Or there are also health kits you can purchase online that will analyze your dna and show what foods might make you gain weight, even tho they are healthy.

I'm going to keep following this as I am still trying to figure it out myself

When someone finds out LET ME KNOW! Lol! It’s a struggle for sure!

I lost a lot of weight when I went on medicine to treat my hashimotos but it really affects everyone differently.

I’m on Synthroid for my Hashimotos but it’s not cutting it alone. I’ve recently joined the gym and that is helping a little bit more but I think it’ll take a while before I see improvements