I am versed on this, since my husband and I eat low fat and meatloaf is his favorite food!!! I usually make it with ground turkey, or pork, or a mixture of meats. Also, ground turkey with a little ground sausage adds a lot of flavor, and not a lot of fat. Also, use egg substitute instead of eggs, makes no difference in taste. Add some wheat germ in place of some bread crumbs, adds fiber. I also chop up a lot of veggies: onions, peppers, carrots, etc. so my meatloaf's are a little chunkier. That way you can have a bigger piece without upping calories. One thing I do that my husband love
With all the veggies I put in it, especially the onion, it adds a lot of moisture. I also add some garlic flavored tomato sauce, sometimes teriyaki sauce, etc. Mixing it with another meat really helps. Half lean ground beef and half turkey works well, or 2/3 turkey, 1/3 pork with a little sausage has good flavor.