Alternative to common sense

I'm not sure if this is a recent development or what, but it turns out that I have to do the exact opposite of normal people when food shopping, e.g., I need to shop when hungry. I just returned from another post-lunch shopping trip and have a bag full of junk food, primarily sweet. So there are two possibilities. One is that I have to shop hungry. The other is that I need to make lists before I go and follow them. Neither may present a legitimate possibility.