Some fatty acids contain C=C double bonds and are said to be unsaturated. Others have no double bonds and are saturated.Monounsaturated fatty acids have one double bond. Polyunsaturated fatty acids have more than one double bond.The presence of a double bond causes the molecule to kink so the molecules cannot pack closely together.This reduces the number and strength of the intermolecular bonds and the lipids are liquid at room temperature rather than solids and are oils rather than fats.Plants contain unsaturated triglycerides(oils) whereas animals contain saturated triglycerides(fats).Excess saturated fats in the diet may lead to coronary heart disease.