You should give yourself one free day, and let that be either Saturday or Sunday, that way you don't feel bad about eating those things, and then it won't be so hard to stay away from them either through out the rest of the week. I give myself freeday Saturday because I know that I'll be going out with friends for coffee and usually we end up going out for dinner. Then Sunday comes along and I start myself out with just eggs and turkey bacon for breakfast and plan the rest of my day out. Another thing that helps out as well, is when you reach for something sugary/high in simple carbs, tell yourself that you'll write it down so that when Saturday comes you can have it. Typically for me by the time Saturday comes around most those things don't sound good and the ones I've been thinking about all week are soooo delicious and sate my sugar cravings that I had been having.
It also makes me feel better that I actually got to enjoy something that was bad for me rather than eating that gross chocolate that has been sitting around that you don't really want to eat cuz it doesn't taste good, but it's there and you just really want something sweet. So then you eat it and then feel twice as guilty because it didn't even taste good!
Hope this helps