Drink water when you're hungry, drink lots of water, don't eat anything outside of meals. Take an adhd medication that makes you less hungry. Stand and walk, sitting doesn't burn many calories, I like to walk circles around my kitchen counter for hours. Distract yourself with work, school, or video games. Don't eat lunch at work or school. Plan your meals and don't eat anything outside of your meals.
Eat dinner early and go to bed early, when you get hungry it will be harder to sleep. When you start waking up at night, drink water and pace around your house. You can take melatonin tablets an hour before you go to sleep but it never helped me sleep and I was taking handfulls, it also wears off at about midnight so you'll be waking up a few times between then and 4 AM anyway. Have something to when you first wake up other than food, you can eat then but don't overdo it, if you wake up really early at least wait until a normal breakfast time like 5 or 6. If your schedules weird then you can make your breakfast time different obviously.
If you fuck up and eat a bunch of crap, don't give up, just don't eat anything else that day and go back to your scheduled meals the next day.