You are having hypothyroidism
.Your thyroid hormones are low,TSH
will be high.You gain wieight inspite of normal food intake in this condition.
Please increase the dose 100micrograms.
You have to take Synthroid
daily till the hormone levels come to normal.
Your TSH has to be checked regularly.
Please consult Endocrinologist
as this condition needs prolonged treatment.
It is not possible to increase BMR or get rid of the disease permanently.
Wish you good health