Why are lipids considered hydrophobic?

Lipids are considered hydrophobic primarily because they repel water due to their molecular structure. The hydrophobic nature of lipids stems from their long hydrocarbon chains, which are nonpolar. Water is a polar molecule, and when nonpolar molecules like lipids come into contact with water, they do not form favorable interactions. Instead, the water molecules tend to aggregate together, minimizing their contact with the hydrophobic lipid molecules.

This intrinsic property of lipids makes them insoluble in water, allowing them to perform various biological functions, such as forming cell membranes, where a hydrophobic barrier is essential. The presence of fatty acid chains in many lipids reinforces this hydrophobic characteristic, making it clear that lipids do not dissolve in water but rather avoid it.