I've learned, through many-a trial and error that I just need to
stay away from sugar--for me, that means straight up sugar and refined carbohydrates. I love sugar cookies as much as the next person, and buttercream frosting... Well, I could eat half a jar of it in a sitting. I have eaten 3/4 of a bag of mint oreo cookies in a sitting, too. I just can't stop myself when I have sugar

I'd say an extra 300-500 calories at lunch definitely isn't worth it--and it especially isn't worth it if it might trigger you to eat more sugar.

That's just my .02 worth.