Since there aren't many details on your situation, this is a shot in the dark, but I guess the question is broad enough that there's no single best answer anyway.
It seems that unhealthy eating is often influenced by at least one of two things: a lack of variety in food or unconsciously (or only semi-consciously) following bad routines.
Here are some ideas:
- Increase the time it takes you to reach food that you know you are eating in excess. During the time it takes you to reach it, reflect upon your choice, reconsider, and only continue if you can think of no better option. Conversely, have a variety of healthy low-energy food always available and easier to reach than any high-energy food.
- When eating, especially when overeating, be in the moment and pay attention on the effects and how you feel afterward. Are you maybe only focusing on the immediate taste, and not giving your body the attention it needs to remember what is good and bad in the longer run? Or is there maybe something in the food that you really need, but could get elsewhere? For example, I've been eating sweet chocolate in huge amounts until I got to know a certain type of 85% black chocolate. Eating one or two pieces of this hugely reduces my craving for other chocolate, usually for the rest of the day. I guess it wasn't the excessive sugar that my body really wanted!
- Increase the variety of food and the amount of vegetables you eat as much as possible. Additionally, try vitamin supplements. You don't want to get hungry from lacking some specific ingredient/mineral/vitamin. Also, pay attention to what exactly you're craving to eat, and what is the best choice to get it. The availability of groceries inversely correlates with obesity, strongly enough that government programs tried to push grocery stores into poorer neighborhoods mainly for this reason. You can eat quite a lot of (pure) vegetables before it's any issue for weight, and maybe you'll find the ones your body was really looking for.
When it comes to self-control, it seems that awareness is a much better tool than willpower. Willpower is limited; you can only force yourself to do so much. But with a deeply ingrained experience of what is good for you and what isn't, it's unlikely that you'll have some craving to overdo it time and again. That's why it can help to do things consciously and to try many different options.
While not literally food, note that drinking may also be an important factor. Drinking tap water (or pure bottled water if tap water is contaminated with anything in your area) is an important difference; if you're usually drinking anything with significant sugar/energy in it, or in fact anything that's not effectively water, I'd recommend to switch to water in a similar way to the food change: always have a glass of water at the ready; if you choose to drink something else, make sure you take time to get it and drink it consciously every time.
While I've never been overweight, I've applied changes similar to the above because of other health reasons, and I'm quite happy with the result.