Fats belong to the lipid family of macromolecules. They serve several roles in the body, including energy storage, structural support, and hormonal regulation. Different forms of fats exist, with the most common being fatty acids and triglycerides. Fatty acids are chain-like molecules with two distinct parts: a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. Because of their hydrophobic tails, fats do not dissolve in water, which helps them absorb fat-soluble vitamins that wouldn’t otherwise dissolve in water.
Representation of a fatty acid molecule
From a dietary perspective, fatty acids can be classified as either saturated or unsaturated fats. Saturated fats have no double bonds between the carbon atoms in their fatty acid chains, making them solid at room temperature. Unsaturated fats, by contrast, have one or more double bonds in their fatty acid chains. These are further classified as monounsaturated (one double bond) or polyunsaturated (multiple double bonds).
Additionally, unsaturated fatty acids can exist in two forms: trans and cis fats. This refers to the arrangement around the double bond. Trans fats have a configuration that allows the fatty acid chain to remain straight, similar to saturated fats. In contrast, cis fats have a bend in their structure, which keeps the chains apart and prevents the molecules from packing tightly together. This is why oils, which are rich in cis fats, are liquid at room temperature, while fats high in trans or saturated fats are solid.
Classification of fat molecules
The distinction between trans and cis fats has important health implications. Trans fats are harder for the body to break down, increasing the risk of heart disease. They are also rare in nature and are often artificially created, making them more difficult for our bodies to process. In contrast, cis fats are naturally occurring and easier for the body to digest and utilize.
While fatty acids are important building blocks of fats, the form in which the body stores fat is triglycerides. A triglyceride consists of one glycerol molecule and three fatty acid chains. When you consume more calories than your body needs for immediate energy, it converts the excess into triglycerides, which are stored in fat cells. These fat cells serve as energy reserves, providing fuel during fasting or prolonged physical activity. When carbohydrates are scarce, the body breaks down triglycerides into fatty acids, which are then converted into energy. So, what types of fat are found in various foods?
