Fats (or triacylglycerols) are uncharged esters of glycerol. In other words, a fat is a glyceride in which glycerol has been esterified with three fatty acids.

The degree of saturation of a triglyceride is a major determinant of the melting point. The greater the degree of saturation, the higher the melting point because the straighter chains allow greater access for mutual interaction through London dispersion forces, thus increasing the electrostatic force of attraction between the molecules. This means that greater internal energy increase is required to separate saturated fats from each other in phase change.

The hydrocarbon chains of a fat represent a more highly reduced form of carbon than in carbohydrates such as glucose. This makes fats very concentrated stores of metabolic energy.