Donating Blood and Calories Lost - Help

I just donated blood too, and I'm curious as well. I'm not going to record it as any exercise, but I will pay careful attention to how I feel and try to eat nutrient-rich foods. I was worried about how I would feel, so I snacked a little to keep up my blood sugar(I'm about 100 calories over today), and though I do feel a little hungry, it's not anything unusual, and I don't feel nauseous. If donating blood does in fact burn a bunch of calories, I'll just let it go under the radar and eat normally.