Though we all know better, it's impossible to study American nutrition properly without looking at fast food. Doing so would be like considering American movie history without considering "Star Wars" and "Raiders of the Lost Ark." McDonald's sausage and cheese biscuit is a popular breakfast item.

A typical sausage and cheese breakfast biscuit is about 6 oz of food, according to nutrition statistics released by McDonald's. Standard ingredients include a biscuit, cheese, sausage patty and scrambled egg.

One sausage and cheese breakfast biscuit contains 510 calories, over one-quarter of the USDA daily allowance. Of those calories, 330 come from fat.

Fat content is as important, if not more important, than calorie totals when understanding how healthy a food is, says Harvard nutritionist Walter Willett. The 330 fat calories in a sausage and cheese biscuit include 14 g of unhealthy saturated fat, more than 70 percent of the USDA recommended limit.