What do fats and oils do in the body, what is the difference between saturated and unsaturated fat, and why does eating too much matter?
The function and dietary sources of fat, the difference between saturated and unsaturated fats, the role of cholesterol, and the effects on health of eating too much fat.
An SQA National 5 Health and Food Technology answer on fats and oils, covering their functions and sources, the difference between saturated and unsaturated fat, the role of cholesterol, and the health effects of eating too much fat.
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What this dot point is asking
The SQA wants you to state the functions of fat, name sources, explain the difference between saturated and unsaturated fat, say what cholesterol is and why it matters, and explain the health effects of eating too much fat.
The functions of fat
Because fat is so energy-dense, even small amounts add a lot of energy to the diet.
Sources of fat
Fat in food is either visible (the fat you can see, such as the fat on meat, butter or oil) or invisible (hidden in foods such as cakes, pastry, crisps, chocolate and processed meals). Knowing about invisible fat matters because it is easy to eat a lot without realising.
Saturated and unsaturated fat
- Saturated fat sources. Butter, lard, fatty meat, hard cheese, cream, and the fat in cakes, biscuits and pastry.
- Unsaturated fat sources. Olive, sunflower and rapeseed oils, oily fish (such as salmon and mackerel), nuts, seeds and avocado.
Current dietary advice is to swap some saturated fat for unsaturated fat, for example using a vegetable oil instead of butter, as well as cutting the total amount of fat.
Cholesterol
Eating a lot of saturated fat raises blood cholesterol. As cholesterol builds up, the arteries narrow and harden, blood flow is reduced, and the risk of coronary heart disease and stroke goes up.
Too much fat
Examples in context
Example 1. Switching the family spread. A family swaps butter for an unsaturated vegetable-oil spread on their toast. Over time this lowers their intake of saturated fat, which helps keep blood cholesterol down without giving up a spread altogether.
Example 2. Choosing oily fish. Including oily fish such as salmon once or twice a week supplies unsaturated fat in place of some saturated fat, and also provides vitamin D, which is a fat-soluble vitamin carried by the fat.
Try this
Q1. State whether saturated fat is usually solid or liquid at room temperature, and name one food that supplies it. [1 mark]
- Cue. Solid, from a food such as butter, lard, fatty meat or hard cheese.
Q2. Name the fatty substance in the blood that builds up in the arteries when too much saturated fat is eaten. [1 mark]
- Cue. Cholesterol.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA N5 style4 marksDescribe two functions of fat in the body and explain two effects on health of eating too much saturated fat.Show worked answer →
A 4-mark answer here covers two functions and two health effects, so split your time evenly.
Function 1. Fat is a concentrated source of energy, providing more than twice the energy per gram of carbohydrate or protein.
Function 2. Fat carries the fat-soluble vitamins A and D around the body, and a layer of fat under the skin helps to insulate the body and keep it warm. Fat also protects organs such as the kidneys.
Effect 1. Too much saturated fat raises the level of cholesterol in the blood, which can build up on the walls of arteries and narrow them.
Effect 2. Narrowed arteries raise the risk of coronary heart disease (CHD), because blood flow to the heart is reduced. Excess fat is also high in energy and contributes to becoming overweight or obese.
Markers reward two clear functions and two clear effects. Writing "fat is bad for you" with no mechanism scores nothing.
SQA N5 style3 marksExplain the difference between saturated and unsaturated fats and give a food source of each.Show worked answer →
This question rewards a clear contrast plus correct sources.
Saturated fat is usually solid at room temperature and comes mainly from animal foods. Eating a lot of it raises blood cholesterol. A source is butter (also acceptable: lard, fatty meat, hard cheese).
Unsaturated fat is usually liquid (an oil) at room temperature and comes mainly from plant and fish foods. It is the healthier choice and does not raise cholesterol in the same way. A source is olive oil (also acceptable: sunflower oil, oily fish, nuts, avocado).
A further point that scores is that current dietary advice is to replace some saturated fat with unsaturated fat, rather than just eating less fat overall.
Markers reward the solid-versus-liquid difference, the cholesterol point, and a correct source for each type. Naming the same food for both scores once.
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Sources & how we know this
- SQA National 5 Health and Food Technology Course Specification — SQA (2017)
- British Nutrition Foundation - Fat — British Nutrition Foundation (2023)