Wilbur O. Atwater, an antique calorimeter, and foods rich in fat illustrating the scientific origins of the 9 calories per gram rule.
Calorie Basics

Who Decided That a Gram of Fat Has 9 Calories?

Older food labels offer an interesting record of how nutrition numbers and labeling rules have changed. One number has stayed remarkably familiar: a gram of fat is counted as 9 calories. We wanted to trace that familiar figure back to the original research and find out how it became the standard. The answer leads back […]