A lot of times, there exists one or in worse cases more, obstacles that keep you from achieving your weight loss goal. Failing in keeping yourself to a certain meal or exercise plan is due to some kind of disturbance in your life because in most of the cases a person knows exactly what they should not eat in order to lose weight, but no matter this knowledge he or she is unable to stick to it. It is just like when you know that you should cross the street where is marked to avoid getting hit by a car, but you anyway cross in the wrong place, and although you’ve got hit already before, you keep crossing in the same place and keep yourself being hit again and again… it sounds stupid, but it is exactly what it happens with food. You know that it is too much or too sugary, unhealthy, full of fat or whatever, but anyway, you keep ingesting.  So, you do not want to commit suicide and don’t want to die, but you throw yourself down from a 50 store building anyway… you wouldn’t do such a thing, would you? We can affirm that we do know that what we eat may be wrong, but we eat it anyway, and meanwhile we dream of having a slim body. 
 So, what is making you do eat what you shouldn’t? Some may say, that it’s the devil, but I don’t go for this version. I would put the question also in another way. What keeps your mind getting off the track, losing the goal from sight? The question have two sides, just like a coin: what makes you do things and what makes you don’t do things? A physical obstacle? It may be, but usually, it is not a disability, or some bad person, or big green dragon that would have locked you up in a tower full of chocolates…no. Usually, it is some kind of mental “background” issue that grabs your attention and makes you focus on the wrong things. And stopping eating at the right time requires a strong mental state, till it becomes a habit. 
 Why do we become weak? What is the mental barrier that keeps you on the right track? The answer is partially bad news for you: I have absolutely no idea, but you know why? Because I don’t know you and your life. One thing I do know, though: the obstacle is there and it is there in your life. So, you are missing an item, but you are given a big sack where 100% you can find your item. You just have to look. 
Start to analyze “your sack”. The good news is that it is guaranteed, that the obstacle is there.  Your sack is actually your own day to day life. Analyzing takes time and attention, but it is anyway much shorter than “forever”, which is going to be your state if you never start analyzing at all. 
 I read somewhere if I remember it was some It guy's blog, that “nothing can be improved which is not measured and tracked”...  The guy is a philosopher! Exactly that. How do you expect to improve your eating habits if you just don't track it? How do you know what has to be reduced, and what has to be increased? Or you just guess it, cause you are so clever? A guess is a guess. Certainty is a fact which you can present in court. For example, how would it sound, to say: I guess he was the guy I saw trying to break the neighbor's car? Was he or was he not? I don't know exactly but might have been... No court will convict anybody according to such statement. And this is how your grown up brain works. If you don't argument something logically it won't care about guesswork, no matter that you believe it does.  It doesn't. Did you write it down? No. Did you show your own brain? No. Then how on earth you expect that it will believe you when you say: I assume that is not that nice...buut, I am not exactly sure why...just don't want it next time, OK? Please! Your brain won't process that. 
 So let me resume: you have no idea why, you have no idea when, you have no idea how, but guess it's not OK?
Does that sound convincing? I believe not. Neither does your mind. So, make a strong case. Prove to your mind that you are right, and only after that expect that it will start to care or urge you to take some action.