exercise
I'm late to this, but figured I would still share.
I didn't start really excercising till 100 pounds down. Though, I do have a very physically active job.
At 200 pounds (down 100) I signed up for a HIIT bootcamp 3 times a week and running 3 times a week. That was maybe late Semptermber/Eatly October. Since then my weight loss has slowed dramatically. I still only eat 800 calories a day. But! I have seen crazy changes in my body composition. My arms and legs are jacked-which is awesome- and I've lost more inches around my waist per month than usual.
Swelling and water retention due to muscles healing are major culprits in slowing down loss. But if you also partake in cardio, you actually begin to produce a higher volume of blood which can cause up to a 5 pound temporary gain (usually closer to 2). The higher volume of blood is a good thing, by the way.
The danger of working out is eating back calories. In my humble opinion, I would totally diregard how many calories you burn during your work out and still eat at your usual caloric intake.
For me, excercise has made weight loss worth it. So much so that I'm actually in the processes of becoming a personal trainer. Basically, you might see a slowling of your loss (you might not) but keep measurement and pictures, and live your healthiest life.