I worked the night shift for about 3 years and lost weight. You have to set regular meal times if possible and abide by them. Focus on protein and never eat carbs without it. Focus on whole foods - lean meat, fish, eggs, beans, 100% whole grains, healthy fats, low fat dairy, fruits, veggies, nuts, seeds,soups, salads, etc. Avoid processed stuff, vending machines, sugary snacks, sugary drinks, caffeine. Drink lots of water. Get sleep and exercise in.