OK OP, please let me explain in a way that you can understand some of the reasons why people 'cheat'
It sounds to me that you have a weight problem possibly due to having a slower metabolism to your friends. You've been eating the wrong things & unfortunately have put on weight as a result. You obviously get no comfort out of eating & it was purely wrong choices made, going from what I've read in your comments, that is.
For a lot of people, myself included, eating is like a comfort blanket. It gives you a rush of endorphins, pleasure, sugar when you feel like you need a boost. It makes you feel happy whilst you're eating whatever it is. You feel bored, you eat, you feel lonely, you eat, you feel upset/angry, you eat. You get the picture.
It just gives a minor distraction from whatever it is you are feeling at that moment, that you don't want to feel. It's basically an addiction, a compulsion. A learned response that's hard to break. Some people may have been eating to medicate for years. Some people may have been abused as a child & turned to eating. They might have an abusive partner & eating makes them feel good. They might have a stressful job. There are a million reasons to turn to eating. The same way as people turn to drugs, alcohol or gambling. They might also be perfectly happy, but just have a problem overeating!
The reason why people 'cheat' is because it's hard to deprive yourself. It's hard to not give in to the compulsion, it's hard to miss out when everyone else is indulging. Sometimes, you might have had a really crappy day and reach for the chocolate because for that second you're eating it, you feel good. If you've been doing this for years, it's a hard habit to break. Just like any other addiction.
Basically it's something in your brain that is bloody hard to turn off!
I know you're young, and it seems very easy for you and you're lucky you feel that way. I just wanted you to see it from another point of view and see why some people are upset and hope you can understand the reasons.
I wish everybody good luck in their weight losses. Keep going guys! We can do it xx