I highly doubt you can actually maintain weight on 800 kcal/day regardless of activity level. That isn't really scientifically plausible. Most people significantly underestimate their caloric intake by not weighing portions or failing to count snacks and beverages.
I use a gram scale and eat only plants with home made bread. What can I say? On average it’s probably 1100kcal per day and weight loss seems invisible.
Maintaining 200 lbs weight even at 1100 kcal/day is still unlikely. That should produce a slow weight loss. Due to natural daily fluctuations it may take several weeks to see a significant change on the scale.
Have you had a resting metabolic rate test? They can tell how many calories you burn based on exhaled gases. I weigh about the same as you and burn about 1700 kcal/day just sitting on the couch.
