Here's the thread Tinky mentioned.
Welcome to my world! I'm currently working 11pm to 9am 4 nights a week in a group home also. I've been working some variationof this for the last 11 years (recently it was 9pm to 9am three nights a week and one 4 hour day - I like 4 ten hour nights better!).
I gained about 40 pounds over the last decade and have lost 90 this year.
Getting enough sleep is essential (and also hard). When you are awake at night your body naturally craves carbs and when you are sleep deprived this is even worse. Getting enough sleep makes controling those cravings much easier. And planning ahead to have healthy options also helps.
I'm terrible at getting sleep - often I only get three or four hours (in hour or two chunks) on the days I'm working and then I sleep 12 hours straight my first night off and revert to a "normal" schedule till it's time to go back to work. It's the only way I've found that works for me and my life.
To lose weight I've been calorie counting (1550 a day) and mostly aiming for whole foods. No "lite" or "diet" foods. An, of course, no "junk" food. I tend to eat a bunch of 300 calorie meals spaced through out the day because there's no good time to have a regular meal. I'm usually not hungry when I first get in to work and in the morning once the kids get up it's too hectic to eat much and then it's my bed time and I don't want to go to bed on a too full stomach and when I get up around 5pm to feed the dogs I don't want to eat too much because I'm always hoping to go back to sleep for a bit before work. Sometimes on my work days I'm lucky to hit 1000 calories because if I have to choose between food and sleep I'll almost always choose sleep.
Here's an article that talks about leptin and ghrelin and how lack of sleep effects your weight: