Well, since I do not use evaporated milk (I prefer to use fresh ingredients) or processed cheese (yuck!), I tried to substitute fat free milk and 2% low fat sharp cheddar. Was not good as sauce was clumpy....low fat and fat free cheese just do not melt correctly. Ended up throwing some Pace Picante on top (0 calories) and it was edible, but just barely. I guess one should not substitute ingredients!