Congratulations on losing 70 lbs and keeping it off for two years! That is fantastic!
It's not surprising that you gained back all the weight you lost when you couldn't eat. I've been reading about this lately; when you fast, your body thinks it is starving and begins storing fat. As soon as you start eating again, your body starts storing everything you eat as fat until you are back up to where you were before. I've noticed the same thing happen to me when I've had the stomach flu.
1,000 calories a day is not enough food. I have a personal trainer and he is really concerned about me eating less than 1200 calories per day because, at that point, you really run the risk that you aren't getting enough nutrients, which tells your body to store fat. I'm surprised that WW recommends plans that are under 1,200 calories per day for anyone.
My approach would be to eat at least 1200 calories every day (or whatever calorie amount you decide makes sense for you) but to eat the same amount whether you exercise or not. That way, on the days that you exercise, you give yourself a little extra calorie deficit (so long as you take in the nutrients, it's okay to burn off a few extra calories through exercise). Right now, you are losing that extra little push because you eat more on the days you exercise.
A couple of thoughts about your exercise:
- It doesn't sound like you are doing any strength training. I just read in
"You on a Diet" that 1 lb of muscle burns between 40 and 120 calories per day just existing (whereas 1 lb of fat burns 1 to 3 calories per day). Building some muscle would increase your metabolism, making it easier for you to both lose and maintain your weight. This obviously isn't going to give you results overnight, but in the long term I think you might really benefit from it.
- Consider running intervals instead of your 3-mile run two or three days a week. Sprint as fast as you can for 1 minute, then walk jog for 1 min, etc. Do this for maybe 15 to 20 minutes. If you google "high intensity interval training" or "HIIT" you'll probably come up with some websites that suggest some more interesting programs than what I've suggested here. Studies have shown that intervals are more effective at burning fat than doing cardio at a steady pace. In fact there are some experts that believe that you shouldn't bother with any cardio other than intervals--just do intervals and weight training. Adding intervals to my workout definitely seemed to help me get off a plateau.
- You also might want to just shake up your exercise routine a bit. If you do the same thing every day, your body adjusts to it and it isn't as effective. Adding intervals is one thing you could do. Weight lifting or resistance training is another. You could also try some incline work (running or walking up stairs or steep hills), adding jump rope, or a cardio DVD (I'm trying to think of things that don't require a gym, since it sounds like you don't belong to one).
Finally, at your current weight you are at about the mid-range for your acceptable BMI. I have found that once you get to this point, weight loss is very slow going and requires being on plan all the time (eating enough food, the right food, and not too much food). A loss of 1/4 to 1/2 lb a week is excellent. An illness where I can't eat will stall my weight loss for weeks.
Don't worry--you lost this weight once, you can lose it again. It's just going to take some time.