Compounds with highly hydrophobic or amphiphilic character.

Lipids are a large group of various compounds. The figure presents lipids derived from glycerol. The hydrophobic part of lipids (blue colour) is often formed of various fatty acids; compounds containing exclusively such hydrophobic constituents are called fats. Because fats can be stored free of water (in contrast to carbohydrates), and because they are highly reduced, they can store high amounts of energy for a long time.

Lipids containing hydrophilic groups (red colour), show amphiphilic characteristics and are the main molecular building blocks of biological membranes.