The fat plans to work out around the availablility of the pizza.  Well, for some people on a tight budget, saving a few bucks for dinner one day is worth it, so I can understand that. I don't have confidence in Planet Fatness hams doing the right thing: but to be fair, there's nothing wrong with eating a slice (or even two, possibly even 3 slices depending on the pizza) in theory even if you are actively trying to lose weight. As long as you're disciplined the rest of the day, that should fit into your calorie budget just fine. Of course, most fats don't have discipline, so planet fatness is just being smart by offering occasional free carbs from the perspective of their business model.