An air fryer uses heat, air, and a fan to make that hot air circulate around food really fast. As a result, the food gets crispy and browned. Think of a marshmallow over a campfire. That browned exterior of the marshmallow is called the Maillard reaction, and it's the same principles used by an air fryer. Air fried fries have around 190 calories per serving compared to 365 calories for a standard serving of fried french fries.