Daily Calorie Needs and Deficit

I have read so much about starvation mode and calorie deficits. I've read that the body can take 31 calories per pound of fat for energy daily before it goes into starvation mode.

My question is, based on calculations done it seems that for a 5'5", 400 lb female, 3140 calories are burned per day with a sedentary activity level. Doing exercises to burn 500 calories per day and cutting calorie intake by 500, still leaves a 2140 per day calorie diet.

When someone is severly obese, is it ok to go past the 1000 calorie standard deficit per day?

Say a 2000 calorie diet and burning 1000 calories from exercise(cardio and strength).

[Renee Radenberg]

The lowest recommended daily intake is 1200 calories which will prevent malnutrition. Any prolong intake of lower calorie amounts will result in a deficiency of nutrients, vitamins and minerals in our body regardless of the size of the person.