How can a poor diet over time lead to diseases such as obesity, heart disease, type 2 diabetes and high blood pressure?
Explain the causes and dietary links of obesity, coronary heart disease, type 2 diabetes and high blood pressure, and suggest dietary prevention
A focused answer on diet-related diseases - obesity, coronary heart disease, type 2 diabetes and high blood pressure - their dietary causes, how they develop, and how diet can prevent them.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
The syllabus wants you to explain how poor eating habits over time cause the main diet-related diseases - obesity, coronary heart disease, type 2 diabetes and high blood pressure - and to suggest dietary changes that prevent them. The central idea is that these diseases develop slowly from long-term excess, and that because the causes are largely dietary, they are largely preventable through diet.
The answer
Obesity
Obesity is having too much body fat, caused by a long-term energy surplus: eating more energy than the body uses, often from fatty and sugary foods and a low-activity lifestyle. Obesity is the gateway problem, because it raises the risk of heart disease, type 2 diabetes, high blood pressure and joint problems.
Coronary heart disease
A diet high in saturated fat raises blood cholesterol. Cholesterol is deposited in the artery walls as fatty plaques that narrow the arteries. When the arteries supplying the heart become narrowed, the heart muscle gets less oxygen; a full blockage causes a heart attack. Too much salt and excess weight add to the risk.
Type 2 diabetes
In type 2 diabetes the body cannot control blood glucose properly. Being overweight, especially carrying fat around the middle, makes cells less responsive to insulin (insulin resistance), so blood glucose stays too high. A diet high in sugar and refined carbohydrate and low in fibre makes this worse. High blood glucose over time damages blood vessels, eyes, kidneys and nerves.
High blood pressure
A diet high in salt raises blood pressure: the body retains water to balance the extra sodium, increasing blood volume and pressure. Being overweight and inactive also raises it. High blood pressure strains the heart and damages arteries, raising the risk of heart attack and stroke. It often has no symptoms, so it is called a "silent" condition.
Preventing diet-related diseases
The same broad changes help across all four:
- Match energy intake to needs to keep a healthy weight.
- Cut saturated fat and total fat; choose unsaturated fats.
- Cut added sugar and sugary drinks.
- Cut salt; flavour with herbs and spices instead.
- Eat more wholegrains, vegetables, fruit and fibre.
- Be physically active.
Examples in context
Example 1. Reducing salt in local food. Many hawker dishes are high in salt from sauces, stock and added seasoning. Asking for less salt or less sauce, and not adding extra soy sauce, is a concrete way to lower sodium intake and protect against high blood pressure, a common condition in Singapore.
Example 2. Choosing kopi kosong. Switching from sweetened kopi to kopi kosong (no sugar) removes several teaspoons of sugar per cup. For someone at risk of type 2 diabetes, repeated daily over months this is a meaningful reduction in sugar and energy intake.
Try this
- Cue. Explain the chain from a high-saturated-fat diet to coronary heart disease. Link saturated fat to raised cholesterol, to fatty plaques narrowing the arteries, to reduced blood flow and heart attack.
- Cue. Explain how being overweight is linked to type 2 diabetes. Link excess fat to insulin resistance, so blood glucose stays high.
- Cue. Suggest three dietary changes that would lower a person's risk of diet-related disease. Recall less salt, less saturated fat and sugar, more fibre and wholegrains, and a healthy weight.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original6 marksExplain how a long-term diet that is high in saturated fat and salt can lead to coronary heart disease and high blood pressure.Show worked answer →
A diet high in saturated fat raises the level of cholesterol in the blood. The cholesterol can be deposited in the walls of the arteries, forming fatty plaques that narrow them. This restricts blood flow to the heart, and if an artery supplying the heart becomes blocked it causes a heart attack, so the disease is coronary heart disease.
A diet high in salt (sodium) raises blood pressure, because the body holds more water to balance the salt, increasing the volume and pressure of the blood. High blood pressure makes the heart work harder and damages arteries, adding further to the risk of heart disease and stroke.
What markers reward: the saturated-fat to cholesterol to narrowed-arteries to heart-disease chain, and the salt to raised-blood-pressure chain, each explained as a sequence rather than just stated.
Original5 marksA person is overweight and has been told they are at risk of type 2 diabetes. Explain how being overweight is linked to type 2 diabetes, and suggest three dietary changes that would reduce their risk.Show worked answer →
Being overweight, especially with excess fat around the middle, makes the body's cells less able to respond to insulin (insulin resistance). The blood glucose then stays too high, which over time is type 2 diabetes.
Three dietary changes: reduce sugary foods and drinks to avoid sharp rises in blood glucose; reduce the total energy and fat eaten, and increase activity, to lose excess weight; and choose wholegrain, high-fibre carbohydrates and more vegetables, which release energy more slowly and help control blood glucose.
What markers reward: the overweight to insulin-resistance to high-blood-glucose link, and three realistic changes (less sugar, less energy/weight loss, more fibre/wholegrain) each tied to controlling glucose or weight.
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