Moderation is just code for not overeating. Eat small portions, but balance out the good with some bad. You can not eat all bad and then expect good results? Best advice: keep leftover dinner. They are cheaper than buying lunch, and way healthier than the mass produced, oil drenched food you buy.
Moderation is the key to losing weight. The first rule of every diet out there: Cut those portions. You can't have this, but you can have so many speckles of this and so many crumbs of that.
I am a great believer in small portion, but I eat anything and everything in small portions... Chocolate, cake, ice cream and sweets included. Come on, we all want to eat a Simba Chippie!! Depriving myself and starving myself in order to cut down my calorie intake is not my idea of living. In the great words of Sid the Sloth: "No Thanks, I choose life!!"
Try to eat healthy, but snack unhealthy on weekends or when you really feel like it. Most of the time, you feel good about eating right and will not be bothered with unhealthy food anyway.
Besides, why would you over do it now on bad stuff and eat the WHOLE lot at once, when you can do it over later?