Go for a mix of 50/50 low fat may and low fat sour cream. If you are really worried about fat calories, make one of these fat free instead of low fat. Reduced fat mayo only has 35 calories and a few grams of fat and it tastes much better than the fat free version, Add lots of chopped veggies, too, like cucumbers and carrot for crunch and flavor. Pickles add more flavor than relish and they aren't so sweet.