Macronutrients Explained: Fat

Updated: Jun 27

Fat is an essential macronutrient made up of fatty acids.

1g fat = 9kcals.

Fats are consumed in the diet in the form of animal fats, sterols, oils and phospholipids.

Fats are broken down in the body into fatty acids during digestion. These can then go on to form more complex lipid molecules such as triglycerides, phospholipids and steroids.

Some fatty acids are essential

  • Alpha-linolenic acid (ALA) (an omega-3 fatty acid)

  • Linoleic acid (LA) (an omega-6 fatty acid)

So must be obtained through the diet. Others are nonessential and can be synthesised endogenously in the body from the above fatty acids.

At some stages in life some fatty acids become essential, and so are 'conditionally essential' . For example the non-essential fatty acid docosahexaenoic acid (DHA) is essential during childhood for brain development.

Fatty acids can be categorised into three types based on their molecular structure:

  • Saturated (SFA)

  • Polyunsaturated (PUFA)

  • Monounsaturated (MUFA)

Saturated fats tend to be found in larger quantities in animal products and are solid at room temperate, for example in butter.

Whereas unsaturated fats tend to be found in larger quantities in plant sources and are liquid at room temperature, for example in olive oil.

Below are lists of examples of foods where the types of dietary fats can be found.