Greek yogurt is yogurt strained to remove much of the liquid whey, which roughly doubles its protein concentration compared with regular yogurt.
USDA FoodData Central lists plain non-fat Greek yogurt at roughly 10 g of protein per 100 g — mostly casein, the slow-digesting milk protein — along with calcium, vitamin B12, phosphorus and, in products with live cultures, lactic-acid bacteria. The Dietary Guidelines for Americans include yogurt in the dairy group of its healthy eating patterns and identify calcium as a nutrient many adults under-consume; the ISSN protein position stand reports that dairy proteins such as casein and whey effectively support muscle protein synthesis as part of total daily protein intake.