Hi Kev,
First of all congrats for graduating. What did you study?
I think the short answer is that there are no short answers. For me it comes down to willpower and restraint. I find it easier to not buy something like, say, crisps than it is to only eat one packet if I know I have six in the cupboard.
I also find that if I try to deny myself everything, I'm more likely to splurge. A reasonable treat every now and then works for me. There's plently of literature showing that most people perform much better with achievable goals than unachievable ones.
I guess there are other things you can try, like snacking on things that won't raise your blood sugar such as meat, eggs, some nuts, some veg, cheese etc. and drinking water, diet coke, tea whenever you get hungry. You could also look at your diet overall to see if you can make changes in what you eat to be able to fill you up more effectively between meals. If you haven't tried low carbing or eating more low GI, you could give those a go. There's lots of advice in the diet forums.
You may well find that a working routine is better for you than university life, once you're in the swing of things.
If you are really struggling, perhaps consider speaking to your GP about whether you could be referred for cognitive behavioural therapy, which would aim to break a cycle of bad habits.
http://www.rcpsych.ac.uk/mentalhealthinfoforall/treatments/cbt.aspx
There are no easy answers though, but people here can offer support and advice. Recognising your issue and sharing it here is a great step though, and shows you do want to get better at this.
Good luck.
