Should I tell my boss why I don't eat the doughnuts he brings to work?

I work in an office with 5 people and the boss brings doughnuts every day for breakfast. I saw on the doughnut store's website that each doughnut has 8 grams of trans fat. Yeah, that is a lot of trans fat (nutritionists recommend no more than 2 grams of trans fat per day and some say that you shouldn't eat any trans fat). Anyway, I don't feel like eating heart attack on a plate. What should I say if the boss asks me why I don't eat the doughnuts? He's the kind of guy that will ask such a question.