I eat 1200 cals watch my sugar and carb intake exercise 5 days a wk. I have hypothyroid and take synthoid. I lost some weight but its now slow down.

May need more cals. 1200 calories is quite low and your body already has trouble maintaining normal metabolism due to hypothyroid. Speak with your doc regarding whether your synthroid (thyroxine) dose needs adjusting, but also consider eating more. When you restrict your calories like that your body thinks it is starving and slows down metabolism further to preserve itself.