When researchers measured and compared their antioxidant activity, they found no significant differences between the fresh, dried and frozen berries.
The real difference is in sugar content. The drying process removes water, which concentrates sugar and raises the caloric content by weight. A cup of fresh or frozen blueberries has about 85 calories and 14 grams of sugar. One half cup of dried blueberries, on the other hand, has roughly 270 calories and 25 grams of sugar.