You're a good-time girl who likes to eat, drink and party, and you hate the idea of restricting your diet. One more mince pie? "It'd be rude not to...tomorrow there won't be any left...you only live once, after all!" And so on and so forth. During the festive season you probably feasted on all the fatty, sweet foods you love most.
Your problem is that as soon as you try and eat less you get hungry and end up giving in to temptation. The solution is to reduce your fat and sugar intake, but stick to your healthy portions, ie don't eat less - just eat healthier.