Losing weight healthily with an eating disordered past?

How does a now overweight woman with a history of anorexia lose weight healthily without falling back into old habits?

This question should be answered by a Doctor who is familiar with you. No one can give advise of this nature, without knowing you.

exercise.
to not fall back into old habits, you must EAT HEALTHILY. avoid junk & fast foods, don't skip meals, and trash the sodas. you also need to exercise but not excessively, just try to squeeze a little exercise into your morning routine. too much of everything (exercise, diet, eating) is bad, so i say you just keep everything balanced.
Find someone who specialise in weight issues. Otherwise look around for healhy eating plan books.
I think you need oversight, perhaps professional, on any diet you choose.

I have worked out a diet that really works for me, and I lose quite slowly about 1-3 pounds a month.

It is a simple system. You have your three meals as usual, neither overindulging nor under-eating.
I walk around 8000 steps a day, unless it rains.

The catch is this: supper is eaten at 4PM and no later than 6PM. No food after supper, however, I found that black coffee, no sugar -- keeps the hunger pains away.

At 2-3PM I permit some snack, an apple pie, an icecream, whatever.

It works, but slowly, and it is not particularly difficult to stick to.

Once in a while I go to a restaurant. If possible I try to make the meal before 6PM, but on occasion the system can bend as long as it is resumed.
you can eat about 1800 calories a day , drink at least 8 glasses of water a day and exersize about 4 or 5 times a week . the most important thing is that it is important to only lose about 2 or 3 pounds a week so that the weight stays off . if you restrict your calories too much you will make your body actually work against you and when you go off you diet , you run the risk of the weight coming back . i know this from personal experience . i had yoyo dieted thru my teens and early adulthood only to gain it back plus more . it was only with more calories between (1800 -2000) , exersize and alot of water that i finally lost weight and kept it off . i lost 70 pounds about 7 years ago and it is still off ! i hope this helped you out , good luck!
personal experience