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Obesity, being overweight or having too much body fat can contribute to other stroke risk factors, including high blood pressure, type 2 diabetes, and high cholesterol.

Your body mass index (BMI) is a measure of whether your weight is in the healthy range. A healthy BMI range is 18.5 to 24.9. Individuals who are overweight and obese are defined by a BMI of more 25 or more (with a score of >30 representing obesity).

Importantly, BMI does not take into account an individual’s body shape or fitness level, and therefore measuring both your waist circumference and BMI can help to determine your risk for diseases such stroke. A healthy waist circumference should be less than 80 cm in women and less than 94 cm in men. These measurements are recommended for people from Caucasian backgrounds; if you’re from a different cultural background, speak with your doctor about your risk.

Eating a healthy diet that is in line with the Australian Dietary Guidelines, and being physically active, can help maintain a healthy weight.

High blood pressure, also known as hypertension, is a measure of the force with which blood presses on the walls of your arteries as it is pumped around your body, and is the leading modifiable risk factor for stroke.

Normal blood pressure is around 120/80 mmHg. If your blood pressure is regularly over 140/90, you have high blood pressure.

High blood pressure puts a strain on blood vessels all over the body, including the arteries that lead to the brain, and can lead to a stroke in several ways:

• It damages blood vessel walls and makes them weaker.
• It can speed up common forms of heart disease.
• It can cause blood clots or plaques to break off artery walls and block a brain artery.

Major contributors to high blood pressure include a poor diet (especially a high salt intake), smoking, being overweight, excessive alcohol consumption, diabetes, and insufficient physical activity.

Being physically inactive can increase your risk of stroke, type 2 diabetes, overweight and obesity, high blood pressure and high cholesterol.

You should be active most days, preferably every day. Our National Physical Activity and Sedentary Behaviour Guidelines recommend that each week, adults should do either:

• 2.5 to 5 hours of moderate intensity physical activity – such as a brisk walk, golf, mowing the lawn or swimming.
• 1.25 to 2.5 hours of vigorous intensity physical activity – such as jogging, aerobics, fast cycling, soccer or netball.
• an equivalent combination of moderate and vigorous activities.

You don’t have to do it all in one go. It is just as effective to exercise a few times a day in shorter bursts.  

The Guidelines recommend minimising the amount of time spent in prolonged sitting and breaking up long periods of sitting as often as possible.

High cholesterol, also known as hyperlipidaemia or dyslipidaemia, contributes to blood vessel disease, which often leads to stroke. Cholesterol is a fat that is made by the body. We also absorb some cholesterol from foods we eat, such as eggs, meats and dairy products.

The main cause of high cholesterol is a diet high in saturated fats, i.e. fats from animal foods. High cholesterol can also be hereditary.

There are two types of cholesterol:

• Low-density lipoprotein (or LDL) is the ‘bad’ cholesterol that builds up on the artery walls.
• High-density lipoprotein (or HDL) is the ‘good’ cholesterol. It is called the good cholesterol because it removes cholesterol from the blood stream. It takes cholesterol from the cells in our body to the liver where it is broken down and removed safely from our body.

The ratio of good cholesterol to bad cholesterol is the key measurement of your stroke risk. The more HDL you have the lower your risk for stroke. The more LDL that you have, the greater your risk for stroke.

When there is too much cholesterol in the blood, it can build up on artery walls and narrow the arteries. This is called atherosclerosis. It can block the flow of blood or cause blood clots, leading to an ischaemic stroke.

Eating a healthy diet that is low in saturated (animal) fats and high in fruit and vegetables, being physically active, not smoking, maintaining a healthy weight, and limiting your alcohol intake, can all lower your cholesterol. Your doctor may also prescribe lipid-lowering medication to reduce your cholesterol. You should be prescribed this medication if you've had an ischaemic stroke.

Smoking doubles your risk of stroke. The more you smoke the greater your risk of stroke.

Tobacco in every form is very harmful to your health. Exposure to second-hand smoke is also dangerous.

Smoking increases your risk of stroke by increasing blood pressure and reducing oxygen in the blood. Smoking also increases the stickiness of the blood. This further increases the risk of blood clots forming.

Tobacco smoke contains over 4,000 toxic chemicals which are deposited on the lungs or absorbed into the bloodstream. Some of these chemicals damage blood vessel walls, leading to atherosclerosis (narrowing and hardening of the arteries). This increases the chance of blood clots forming in the arteries to the brain and heart.

The immediate health benefits from quitting smoking include:

• Within a month after a person stops smoking, blood pressure returns to its normal range.
• The risk of heart attack and stroke starts to drop immediately after a person stops using tobacco products, and can drop by as much as half after one year.
• After fifteen years your risk of stroke and heart attack is almost the same as that of a person who has never smoked.

Our bodies need a hormone called insulin to turn sugar from our food into energy. If you have type 2 diabetes, your body becomes resistant to insulin and it does not make enough insulin to keep up. This means your body has difficulty absorbing the sugars from food.

Over time, this can lead to increases in fatty deposits or clots on the inside of blood vessel walls. If untreated or undiagnosed, these clots can narrow or block the blood vessels in the brain, cutting off blood supply and causing a stroke.

People with diabetes are also more likely to have high blood pressure, which can also increase your risk of stroke.

The risk of getting type 2 diabetes is higher for people who are:

• Older (over 55 years of age), as the risk increases with age.
• Over 45 years of age and have high blood pressure.
• Over 45 years of age and overweight.
• From a family with a history of diabetes.

If you have type 2 diabetes it is important to keep your blood sugars within a recommended range, which can usually be achieved by maintaining a healthy diet and regular exercise.