I don't know what your medical issues are, so they may prevent you from some of these things. Then again, sometimes losing weight and increasing physical activity can be beneficial to many medical conditions, so...it could go either way. In any event, these are some things I do to stay healthy/keep in shape on the go:
1. If you can't plan your meals, putting more thought into your grocery shopping can be helpful. BUY healthy to begin with, especially more fruits, juices, veggies and leaner meats/cheeses, etc. Don't buy soft drinks, chips, etc. If you want those things for a treat, as Grace said, don't necessarily deny yourself, but sometimes the fact that something is not on hand makes us think twice about it. If we have to run down the street for ice cream, rather than to the freezer, resisting is a whole lot easier. haha
Examples:
If you have children (or a husband haha) who like the sugary cereals, try buying something a little more healthy (more fibrous) with fruit already in it, because you KNOW we end up eating what they eat.
If your family likes Italian food, buy tomato based sauces rather than the alfredo based stuff. Tomato based sauces may contain more sugar, but they contain a LOT less fat and contain vitamins if your kids/husband are big fans of other veggies.
We all need chocolate fixes from time to time. Sugarfree fudge pops or puddings can help a LOT - lower calories AND a lot less fat.
What fat percentage is your milk? It's a subtle change that can make a difference. I don't like to DRINK skim milk, but I do use it when I cook.
What is the fat content of the meats you are eating? Do you trim as much of the fat off as possible? Eat more fish and chicken? How are preparing it? Frying adds a LOT of fat and calories. Consider baking as much as possible.
2. Consider trying Daniel's fast for a season (Daniel Chapter 1). You won't go hungry and you will lose weight without even thinking about it. I do it every now and then for prayer purposes. Basically, you cut out pleasant breads (pretty much anything containing yeast), anything from the vine (booze and a lot of the highly sugary/fatty sauces and dressings we put on our foods) and meats. I do eat fish or chicken a couple of times during the week when I'm doing this for longer than a month. The first time I did this, I did it because my whole church was doing it, not for dieting purposes. But I found that I had a lot more energy and would generally lose between 5-10 lbs anytime I tried it. (P.S. - It's also helpful with what we ladies call "water weight" as a lot of the foods we eat and some of the things we drink cause us to retain more water, especially during umm...certain times. haha)
3. Get moving as much as possible. We ladies are frustrated sometimes because it's easier for guys to lose weight, but the bottom line is that they CAN because they have more muscle mass. Muscle burns calories. It doesn't have to be some complex fitness regiment, unless you're into that sort of thing. Most of our work schedules don't accommodate that very well though, so make it something that works for you.
As Grace said, take a walk...go for a bike ride...get friends together for a ladies only dance class/fitness program. Buy a Wii and USE the sports pack or Wii Dance (a personal favorite haha). Summer is coming on...play volleyball, badminton, go swimming... If you have kids, go outside and PLAY with them: fly kites, rollerskate, play tag, fly frisbees..
When my schedule doesn't permit that, I try to incorporate a mild workout during the day: 50 sit ups, 50 pushups (the REAL ones, not the sissy kind - more benefits for your arms, shoulders, back and....um...it will keep the girls where they should be) and 100 leg lunges or squats. Build up to this over time if you have to, but again, talk with your doc if this is a medical risk for you. I can do this while I'm cooking, watching the news, ironing, doing laundry.. You don't need expensive equipment. These three exercises alone cover most of the major muscle groups and are awesome for toning.
We ladies convince ourselves that we have to fill our calendars taking care of everyone but ourselves, but if we DON'T take care of ourselves, we won't be able to help anyone else either at some point. Our bodies are the temples of God. We should be good stewards. But, again, I do realize that certain health issues can prevent or call for modication of some of these things.
Praying for you and hoping this info is helpful.
P.S. - Be sure you are getting enough SLEEP!!! Your body needs it for renewal purposes AND the lack of sleep can lead to cravings and overeating.