What is the role of fat?

By Hannah Ng’uni

Photo by Karolina Grabowska on Pexels.com

General healthy eating guidelines – Fats

Today, we take a closer look at another food group essential for a healthy balanced diet – Fats. Fat is one of three macronutrients, which is a nutrient the body needs in a larger quantity for energy and body functions. However, unlike the other two macronutrients we have covered (carbohydrates and protein), fats are the most concentrated source of calories providing 9kcal/g, more than double the amount per gram of carbohydrate and protein (4kcal/g). Therefore, ‘larger quantity’ mentioned earlier does not mean eating more fats. Sorry to be the party pooper!

As always if you have any medical conditions, please seek advice from your GP before making any drastic dietary changes.

The Eatwell Guide (2016)

Fats – basics

You will come across the term ‘lipids’ used when describing fats, these are further described by their chemical and biological structure and function. Fats are made up of different components i.e. glycerol, fatty acids, phospholipids (e.g. cholesterol); each participating in different metabolism processes. But not to bore you with the science, we will focus on the key information about dietary fats.

Fun fact: the body makes cholesterol and the cholesterol we obtain from the diet contributes a small portion to the total amount however too much cholesterol can increase the risk of cardiovascular diseases.

   Two main types of dietary fats and food sources:

  1. Saturated fats:

Chemical structure – fatty acids completely filled with hydrogen.

Saturated fats are often solid at room temperature e.g. butter, lard, ghee, cheese, cream, suet, and fatty cuts of meat.

Vegetable oils high in saturated fats include coconut oil and cream, palm oil, cocoa butter.

Food products that have been made with these fats also contribute to saturated fat intake i.e. cakes, biscuits, pastries, chocolate, and some savoury snacks.

  • Unsaturated fats:

Chemical structure -fatty acids with either one carbon double bond (monounsaturated) or two or more double bonds and fewer hydrogens (polyunsaturated).

Unsaturated fats are often liquid at room temperature and are mainly of plant origin. Monounsaturated fats are found in olive oil, rapeseed oil, vegetable oil spreads, nuts, avocado, and olives.

Omega 3 and Omega 6 are termed essential polyunsaturated fatty acids because the body cannot make them therefore, we need to obtain a small amount from the diet.

Omega 3 is found in naturally oily fish e.g. salmon, mackerel, sardines, and some nuts and seeds (walnuts, linseeds).

Omega 6 is found in vegetable oils/spreads, nuts, and seeds.

Note: Foods tend to contain a mixture of both saturated and unsaturated fatty acids but are usually described as ‘saturated’ or ‘unsaturated’ according to the proportions of fatty acids present.

What is the role of fat?

There is much debate about fats and their health effect however a large body of scientific evidence points to reducing fat intake and replacing saturated and with unsaturated fats in the diet as being protective against cardiovascular diseases.

Some functions of fat are summarised below:

  • Fats are essential for the transportation and absorption of vitamins A, D, E and K that our bodies require to maintain good health.
  • A source of energy for the body.
  • Provides insulation and protection around delicate body organs. However, excess visceral fat (fat that shields body organs) can pose a health risk.
  • Because of the various properties of fat, it contributes to flavour, odour, texture and shelf-life of foods.

Top tips from the Eatwell Guide (2016):

  • Choose lean cuts of meat and mince and eat less red and processed meat.
  • Aim for at least 2 portions of fish every week, 1 of which should be oily.
  • Unsaturated fats are healthier fats and include vegetable, rapeseed, olive and sunflower oils.
  • Foods like chocolate, cakes, biscuits, sugary soft drinks, butter, ghee and ice cream are not needed in our diet, so should be eaten less often and in smaller amounts.

Additional information:

British Dietetic Association (2022). Fat Facts: Food Facts Sheet. https://www.bda.uk.com/resource/fat.html

NHS (2020). Fats. The Facts. https://www.nhs.uk/live-well/eat-well/different-fats-nutrition/

NHS (2019). The Eatwell Guide. https://www.nhs.uk/live-well/eat-well/the-eatwell-guide/

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