An<unk>  is a fat or fatty acid in which there are one or more double bonds in the fatty acid chain. This included:
monounsaturated if it contains one double bond
Polyunsaturated if it contains more than one double bond. This includes omega-3 fatty acid and omega-6 fatty acid.
Where double bonds are formed, hydrogen atoms are eliminated. Thus, a saturated fat is "saturated" with hydrogen atoms. In cellular metabolism hydrogen-carbon bonds are broken down - or oxidized - to produce energy, thus an<unk>  molecule contains somewhat less energy (i.e fewer calories) than a comparable sized saturated fat. The greater the degree of<unk> uration in a fatty acid (ie, the more double bonds in the fatty acid), the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect<unk>  from lipid peroxidation.<unk> s also have a more enlarged shape than saturated fats.
Unsaturated fat
Saturated fat
Starch
Diol
Essential fatty acid
Omega-3 fatty acid
Cholesterol
Polyphenol