We can understand that you might be thinking about using low-fat yogurt here. You're free to do as you please, of course, but we'd like to express a word of caution. The lower the percentage of fat in your yogurt, the more water there will be. This means that the end product will be icier and not as soft or smooth. A thicker Greek yogurt with a higher fat percentage will freeze with a less icy consistency. Just something to keep in mind as you're considering your options.