Battle of the bulge

Why is it when you know you need to lose weight and watch what you are eating your cravings for junk food seem to intensify?? I am currently addicted to chocolate! It is all I want to eat at the moment!! Thankfully my will power is strong enough that I do resist a lot of the time. Cadbury's chocolate buttons being my favourite and my real weakness - which reminds me, I will send some in the next aussie package(some birthdays coming up), so, the battle of the bulge continues!! We are going to a wedding this month and I saw a beautiful dress in town but I am torn on buying it. It is fairly expensive and if I buy it in my size now and lose weight I won't get to wear it again, on the other hand if I don't buy it you can be sure I will not lose weight and it would fit me anyway but I wouldn't have it. Ideally I would just prefer to tone up more (less saggy belly etc etc) which would not necessarily mean a change in dress size?!!? All of this is hypothetical anyway because I have not tried on the dress yet and I'm sure as usually happens with these things I will hate it on me and not want to buy it anyway!!! Aahh the joys of it all!!!