There's only one thing that has ever worked for me: remind myself how much better I feel when I eat a certain way.

Last night I went to an Italian restaurant. I meant to order a soup and a small side of tortellini but they instead brought me the soup plus a full-sized entree... plus the fresh bread and butter. Instead of asking them to take it back or restraining myself I ate it all.

I felt guilty afterward but what I focused on was how it made me feel, physically. I noted that heavy feeling, the food coma, the way I actually FELT bigger around the stomach and waist, the tightness in my belt, and the gastrointestinal discomfort later. I combined this with the feelings of guilt and lower self-esteem that came from not doing what I intended to do. The result was enough for me to genuinely say to myself "wow, that was totally not worth the discomfort."

I notice that as I really pay attention to how my body responds to certain foods I'm able to associate those foods (and large portion sizes) with the bad physical and mental states that occur afterward instead of all the comfort and anticipation that occurs before and during. I really think that most people who have problems with overeating are facing strong positive emotional connections with the food (not only the type, but the amount). All the self-flagellation and pep talks have done nothing for me on this front, but simply noticing that I actually feel like complete crap afterwards makes me more and more disinclined to eat this way.

One more example: at lunch today I was tempted by some pulled pork and green beans and tuna salad. I decided to get a very small portion of pork and a higher portion of green beans and kale, and I made sure it was a SMALL meal. I was able to do this without hesitation because I knew I would feel physically tired and bloated if I ate any more. In the past I would have said to myself "self, I know you want to eat everything in sight and then go back for seconds but you really shouldn't". But that doesn't work for me. Reminding myself of how I want to feel AFTER I eat is the only thing that does.

I hope this helps!