Non-communicable diseases and lifestyle factors

What you'll learn

What non-communicable diseases are, and why they often have several interacting causes.
How diet, exercise, alcohol and smoking affect disease risk.
How to calculate and interpret BMI and waist:hip ratio.
How to evaluate treatments for cardiovascular disease.

Communicable and non-communicable diseases

A disease is a condition that affects how the body works. Some diseases are caused by pathogens, but many are not.

Definition

Non-communicable disease

A non-communicable disease is a disease that is not passed from person to person. It is often long-term and may be affected by lifestyle, genes, age and environment.

Examples include:

cardiovascular disease — disease of the heart and blood vessels
many forms of cancer — diseases caused by uncontrolled cell division
some lung diseases, such as emphysema
some liver diseases
diseases influenced by nutrition, such as obesity and malnutrition

Non-communicable diseases are often caused by the interaction of several risk factors, not just one simple cause.

Concept map showing lifestyle and inherited risk factors interacting to influence non-communicable diseases

Definition

Risk factor

A risk factor is anything that increases the chance of developing a disease. It does not guarantee that the disease will happen.

Key Idea

Several factors usually interact

For many non-communicable diseases, risk is affected by a combination of lifestyle factors, inherited factors, age and environment. Exams often reward answers that say “increases the risk of” rather than “causes”.

Lifestyle factors

A lifestyle factor is a feature of how someone lives that can affect health. In this topic, the key lifestyle factors are:

diet
exercise
alcohol consumption
smoking

These can affect health at different scales:

local level — families, schools, workplaces, GP surgeries and local hospitals
national level — the NHS, government health campaigns, food labelling, taxation and workforce health
global level — worldwide patterns of obesity, malnutrition, smoking, alcohol use and disease

Diet, exercise, obesity and malnutrition

Your body needs energy and nutrients from food. If the energy taken in from food is greater than the energy used in exercise and normal body processes, the excess may be stored as fat.

Definition

Obesity

Obesity is having too much body fat, which increases the risk of health problems such as cardiovascular disease and type 2 diabetes.

Exercise helps because it:

increases energy use
strengthens the heart and circulation
helps maintain a healthy body mass
can reduce blood pressure

Diet matters because foods high in fat and sugar can increase energy intake, while a balanced diet provides the nutrients needed for healthy body function.

Definition

Malnutrition

Malnutrition means an unhealthy imbalance of nutrients. It can mean too little food, too much food, or a lack of specific nutrients such as protein, iron or vitamins.

So malnutrition is not just “not eating enough”. Obesity can also be linked to malnutrition if someone has too much energy intake but too few essential nutrients.

Calculating BMI

BMI stands for body mass index. It is a quick estimate of whether someone’s mass is healthy for their height.

m)2\text{BMI} = \frac{\text{mass in kg}}{(\text{height in m})^2}

BMI is measured in kilograms per metre squared, but in GCSE answers you will often just calculate the number.

As a rough adult guide:

below 18.5 suggests underweight
18.5 to 24.9 suggests healthy mass
25 to 29.9 suggests overweight
30 or above suggests obesity

Example

Calculating BMI

A person has a mass of 68 kg and a height of 1.70 m. Calculate their BMI.

Square the height because the formula uses height squared:
$1.70^2 = 2.89$
Substitute into the BMI equation:
$BMI=682.89\text{BMI} = \frac{68}{2.89}$
Calculate the value:
$BMI≈23.5\text{BMI} \approx 23.5$
Compare with the adult guide: 23.5 is in the healthy range.

Common Mistake

Forgetting to square the height

A very common BMI error is doing mass divided by height, instead of mass divided by height squared. Always square the height first.

Waist:hip ratio

BMI is useful, but it does not show where body fat is stored. Fat stored around the abdomen is linked with a higher risk of cardiovascular disease.

The waist:hip ratio compares waist circumference with hip circumference.

circumference\text{waist:hip ratio} = \frac{\text{waist circumference}}{\text{hip circumference}}

Both measurements must be in the same unit, such as centimetres. The final ratio has no unit.

Example

Calculating waist:hip ratio

A person has a waist circumference of 88 cm and a hip circumference of 96 cm. A survey says a waist:hip ratio above 0.90 is high risk. Decide whether this person is in the high-risk group.

Check that both measurements use the same unit: both are in centimetres, so no conversion is needed.
Substitute into the equation:
$ratio=8896\text{waist:hip ratio} = \frac{88}{96}$
Calculate the ratio:
$8896≈0.92\frac{88}{96} \approx 0.92$
Compare with the threshold: 0.92 is greater than 0.90, so this person is in the high-risk group for this survey.

Tip

Use the threshold you are given

You do not usually need to memorise waist:hip risk thresholds for GCSE. If the exam gives a threshold, calculate the ratio and compare it carefully.

Alcohol and liver disease

The liver breaks down alcohol. Drinking too much alcohol over time can damage liver cells.

This can lead to:

fatty liver disease, where fat builds up in liver cells
inflammation of the liver
cirrhosis, where scar tissue replaces healthy liver tissue

Scar tissue reduces how well the liver works. This can affect the liver’s ability to process toxins, store useful substances and make important chemicals for the blood.

Key Idea

Alcohol increases liver disease risk

Long-term heavy alcohol intake increases the risk of liver disease because the liver has to break down alcohol, and this can damage liver cells.

Smoking and cardiovascular disease

Cardiovascular disease, often shortened to CVD, affects the heart and blood vessels. Smoking increases the risk of CVD in several ways.

Chemicals in tobacco smoke can damage the lining of arteries. Fatty material can then build up in artery walls, forming plaques. This narrows the artery and makes it harder for blood to flow.

Smoking can also:

increase blood pressure
increase heart rate
make blood more likely to clot
reduce how much oxygen the blood can carry, because carbon monoxide binds to haemoglobin

If coronary arteries, which supply the heart muscle, become narrowed or blocked, this can lead to coronary heart disease or a heart attack. If arteries supplying the brain are blocked, this can lead to a stroke.

Common Mistake

Saying smoking only affects the lungs

Smoking does damage the lungs, but it also strongly affects the cardiovascular system. In this spec point, link smoking to heart and blood vessel disease.

Local, national and global effects

Lifestyle factors do not only affect one person.

At a local level, high rates of smoking, obesity or alcohol misuse can increase pressure on GP surgeries, hospitals and families. Local councils may respond with sports facilities, stop-smoking services or healthy eating programmes.

At a national level, non-communicable diseases can increase NHS costs and reduce the number of healthy workers. Governments may use health campaigns, food labelling, alcohol guidance or taxes on cigarettes.

At a global level, patterns vary between countries. Some populations face malnutrition due to poverty, conflict or food shortages. Other populations have rising obesity rates due to high-energy diets and less physical activity.

Tip

Correlation is not always causation

Graphs may show a correlation, such as higher smoking rates being linked with more cardiovascular disease. To argue causation, look for a biological explanation and good-quality evidence from large, representative samples.

Treatments for cardiovascular disease

Cardiovascular disease can be treated in different ways. You need to be able to evaluate treatments, which means giving advantages and disadvantages and making a balanced judgement.

Life-long medication

Medication may be taken for many years, sometimes for life.

Examples include:

statins, which help lower blood cholesterol
medicines that reduce blood pressure
anticoagulants or antiplatelet drugs, which reduce the chance of blood clots

Advantages:

can reduce risk without surgery
useful for long-term prevention
can be suitable for many patients

Disadvantages:

may have side effects
must be taken regularly
can be costly over time
does not instantly remove an existing blockage

Surgical procedures

Surgery may be needed if blood flow is seriously reduced.

Examples include:

inserting a stent to hold a narrowed artery open
coronary bypass surgery, where blood is redirected around a blocked artery

Advantages:

can improve blood flow quickly
may reduce symptoms such as chest pain
can be life-saving in serious cases

Disadvantages:

carries risks such as infection, bleeding or blood clots
recovery time may be needed
does not remove the need to reduce risk factors afterwards

Lifestyle changes

Lifestyle changes include:

stopping smoking
increasing exercise
improving diet
reducing alcohol intake
losing excess body mass

Advantages:

usually low cost
improves overall health
reduces risk of several diseases, not just CVD
avoids surgical risks and drug side effects

Disadvantages:

requires long-term motivation and support
effects may be slower
may not be enough alone if disease is severe or inherited risk is high

Example

Choosing a cardiovascular treatment plan

A patient has narrowed coronary arteries, high cholesterol and smokes. Explain why a doctor might recommend more than one type of treatment.

The narrowed coronary arteries are an immediate problem because the heart muscle may not get enough oxygen. A stent or bypass surgery could improve blood flow more quickly than lifestyle changes alone.
High cholesterol increases the chance of more fatty plaques forming. A statin could reduce cholesterol and lower future cardiovascular risk.
Smoking damages arteries and raises the chance of blood clots. Stopping smoking would reduce the underlying risk factor, so it helps prevent the disease getting worse.
A combined plan is stronger than one treatment alone because surgery can treat the blockage, medication can reduce risk, and lifestyle changes can address the causes.

Exam technique

In the exam

Use careful wording: lifestyle factors usually increase the risk of disease rather than definitely causing it.
For BMI and waist:hip questions, write the equation, substitute values, calculate, then compare with any category or threshold given.
When evaluating treatments, include both advantages and disadvantages, then link your judgement to the patient’s situation.

Self review

Check yourself

Why can two people with the same lifestyle have different risks of developing a non-communicable disease?
How do you calculate BMI, and why must height be squared?
Give one advantage and one disadvantage of using surgery to treat cardiovascular disease.

What you'll learn

What non-communicable diseases are, and why they often have several interacting causes.
How diet, exercise, alcohol and smoking affect disease risk.
How to calculate and interpret BMI and waist:hip ratio.
How to evaluate treatments for cardiovascular disease.

Communicable and non-communicable diseases

A disease is a condition that affects how the body works. Some diseases are caused by pathogens, but many are not.

Definition

Non-communicable disease

A non-communicable disease is a disease that is not passed from person to person. It is often long-term and may be affected by lifestyle, genes, age and environment.

Examples include:

cardiovascular disease — disease of the heart and blood vessels
many forms of cancer — diseases caused by uncontrolled cell division
some lung diseases, such as emphysema
some liver diseases
diseases influenced by nutrition, such as obesity and malnutrition

Non-communicable diseases are often caused by the interaction of several risk factors, not just one simple cause.

Concept map showing lifestyle and inherited risk factors interacting to influence non-communicable diseases

Definition

Risk factor

A risk factor is anything that increases the chance of developing a disease. It does not guarantee that the disease will happen.

Key Idea

Several factors usually interact

Lifestyle factors

A lifestyle factor is a feature of how someone lives that can affect health. In this topic, the key lifestyle factors are:

diet
exercise
alcohol consumption
smoking

These can affect health at different scales:

local level — families, schools, workplaces, GP surgeries and local hospitals
national level — the NHS, government health campaigns, food labelling, taxation and workforce health
global level — worldwide patterns of obesity, malnutrition, smoking, alcohol use and disease

Diet, exercise, obesity and malnutrition

Your body needs energy and nutrients from food. If the energy taken in from food is greater than the energy used in exercise and normal body processes, the excess may be stored as fat.

Definition

Obesity

Obesity is having too much body fat, which increases the risk of health problems such as cardiovascular disease and type 2 diabetes.

Exercise helps because it:

increases energy use
strengthens the heart and circulation
helps maintain a healthy body mass
can reduce blood pressure

Diet matters because foods high in fat and sugar can increase energy intake, while a balanced diet provides the nutrients needed for healthy body function.

Definition

Malnutrition

Malnutrition means an unhealthy imbalance of nutrients. It can mean too little food, too much food, or a lack of specific nutrients such as protein, iron or vitamins.

So malnutrition is not just “not eating enough”. Obesity can also be linked to malnutrition if someone has too much energy intake but too few essential nutrients.

Calculating BMI

BMI stands for body mass index. It is a quick estimate of whether someone’s mass is healthy for their height.

m)2\text{BMI} = \frac{\text{mass in kg}}{(\text{height in m})^2}

BMI is measured in kilograms per metre squared, but in GCSE answers you will often just calculate the number.

As a rough adult guide:

below 18.5 suggests underweight
18.5 to 24.9 suggests healthy mass
25 to 29.9 suggests overweight
30 or above suggests obesity

Example

Calculating BMI

A person has a mass of 68 kg and a height of 1.70 m. Calculate their BMI.

Square the height because the formula uses height squared:
$1.70^2 = 2.89$
Substitute into the BMI equation:
$BMI=682.89\text{BMI} = \frac{68}{2.89}$
Calculate the value:
$BMI≈23.5\text{BMI} \approx 23.5$
Compare with the adult guide: 23.5 is in the healthy range.

Common Mistake

Forgetting to square the height

A very common BMI error is doing mass divided by height, instead of mass divided by height squared. Always square the height first.

Waist:hip ratio

BMI is useful, but it does not show where body fat is stored. Fat stored around the abdomen is linked with a higher risk of cardiovascular disease.

The waist:hip ratio compares waist circumference with hip circumference.

circumference\text{waist:hip ratio} = \frac{\text{waist circumference}}{\text{hip circumference}}

Both measurements must be in the same unit, such as centimetres. The final ratio has no unit.

Example

Calculating waist:hip ratio

A person has a waist circumference of 88 cm and a hip circumference of 96 cm. A survey says a waist:hip ratio above 0.90 is high risk. Decide whether this person is in the high-risk group.

Check that both measurements use the same unit: both are in centimetres, so no conversion is needed.
Substitute into the equation:
$ratio=8896\text{waist:hip ratio} = \frac{88}{96}$
Calculate the ratio:
$8896≈0.92\frac{88}{96} \approx 0.92$
Compare with the threshold: 0.92 is greater than 0.90, so this person is in the high-risk group for this survey.

Tip

Use the threshold you are given

You do not usually need to memorise waist:hip risk thresholds for GCSE. If the exam gives a threshold, calculate the ratio and compare it carefully.

Alcohol and liver disease

The liver breaks down alcohol. Drinking too much alcohol over time can damage liver cells.

This can lead to:

fatty liver disease, where fat builds up in liver cells
inflammation of the liver
cirrhosis, where scar tissue replaces healthy liver tissue

Scar tissue reduces how well the liver works. This can affect the liver’s ability to process toxins, store useful substances and make important chemicals for the blood.

Key Idea

Alcohol increases liver disease risk

Long-term heavy alcohol intake increases the risk of liver disease because the liver has to break down alcohol, and this can damage liver cells.

Smoking and cardiovascular disease

Cardiovascular disease, often shortened to CVD, affects the heart and blood vessels. Smoking increases the risk of CVD in several ways.

Chemicals in tobacco smoke can damage the lining of arteries. Fatty material can then build up in artery walls, forming plaques. This narrows the artery and makes it harder for blood to flow.

Smoking can also:

increase blood pressure
increase heart rate
make blood more likely to clot
reduce how much oxygen the blood can carry, because carbon monoxide binds to haemoglobin

Common Mistake

Saying smoking only affects the lungs

Smoking does damage the lungs, but it also strongly affects the cardiovascular system. In this spec point, link smoking to heart and blood vessel disease.

Local, national and global effects

Lifestyle factors do not only affect one person.

Tip

Correlation is not always causation

Treatments for cardiovascular disease

Cardiovascular disease can be treated in different ways. You need to be able to evaluate treatments, which means giving advantages and disadvantages and making a balanced judgement.