As I read your post, I was envious at first! I have lost 20 lbs since Oct 1 thanks to my lupus and gastroparesis. This is not good either.
My only advice would be to pick a diet and stick to it. What you want is weight maintenance and you get instructions on that from Richard Simmons Deal A Meal to Weight Watchers. I am a Deal A Meal fan. WHen I want to lose, I use 1200 calories a day and I exercise daily. When I want to maintain my weight I work up to 1400 and then to 1600 and I vary this depending on the amount of exercise I am doing. THey have enough cards for an 1800 calorie a day diet, which is low, but most women gain at 2000 or more because of our hormonal balance. The best part of this diet is its balance and for you, the fact that you have to measure and eat enough. YOu'll have 5 slices of whole grain bread, 7 to 8 ounces of lean protein, 4 vegetable servings (4 cups) and 3 to 4 pieces of whole fruit (but they are small pieces like 1/2 a banana is ONE fruit serving), 3 fats (3 teaspoons) and 3 8-ounce glasses of milk and 2 freebies. If you eat as directed by every card, you'll start to feel better and you might put a little bit of weight back on, not 100 lbs, but maybe 10. Because you are so thin, after you have eaten all your cards for the day, you can have a few cookies and a cup of tea or not worry about a slice of cheesecake.
I don't go for low carb diets. I did that in 1999 and I lost about 25 lbs, but my triglycerides when down in the low 70s. I complained to my homeopath that I could not think straight and didn't know why. She said that my triglycerides were actually a little too low for optimal brain function and I had to start eating a slice of bread everyday. Since then, I have become vegan. I don't worry about what I eat, because I don't fry any foods and my meals are so heavy in vegetables and soy protein. This is probably contributing to my current weight loss, but doesn't entirely account for it. I just can't tolerate fats in animal products, and I am allergic to dairy and eggs, this choice made sense.
Long long story short, find a way to eat sensibly and do it in a way that makes you accountable to yourself on a daily basis. THe cards are good because you can see what you are or are not doing. They make grocery shopping easier and they are sorta fun in a brainless eating way. LOL
The Lady Dragonfly
Yes, it was me...I know because I was there when I did it. Lupus sufferer, bipolar II sufferer. Currently on Indocin for chronic pericarditis related to lupus, and cherishing every deep breath without pain. Currently in graduate school for mental health counseling, class of Fall 2007. Vegan and loving it!