Calorie-wise, nonfat fro-yo is the best choice. To ensure you’re getting some good-for-you probiotics with your dessert, look for the National Yogurt Association Live & Active Cultures seal (on packaging and in shops), though fro-yo delivers about a tenth of what unfrozen yogurt offers.
90-100 calories, 0 g sat. fat (nonfat) per 1/2 cup vanilla.
120-180 calories, 1-1.5 g sat. fat (low-fat) per 1/2 cup vanilla.