BMI & Blood Pressure
What is BMI?
The body mass index (BMI) is a measure that uses your height and weight to work out if your weight is healthy.
The BMI calculation divides an adult's weight in kilograms by their height in metres squared. For example, A BMI of 25 means 25kg/m2.
For most adults, an ideal BMI is in the 18.5 to 24.9 range.
For children and young people aged 2 to 18, the BMI calculation takes into account age and gender as well as height and weight.
If your BMI is:
- below 18.5 – you're in the underweight range
- between 18.5 and 24.9 – you're in the healthy weight range
- between 25 and 29.9 – you're in the overweight range
- between 30 and 39.9 – you're in the obese range
What is Blood Pressure?
When your heart beats, it pumps blood round your body to give it the energy and oxygen it needs. As the blood moves, it pushes against the sides of the blood vessels. The strength of this pushing is your blood pressure. If your blood pressure is too high, it puts extra strain on your arteries (and your heart) and this may lead to heart attacks and strokes.
How you can tell if you have high blood pressure?
Having high blood pressure (hypertension) is not usually something that you feel or notice. It does not tend to produce obvious signs or symptoms. The only way to know what your blood pressure is, is to have it measured.
Blood pressure is measured in ‘millimetres of mercury’ (mmHg) and is written as two numbers. For example, if your reading is 120/80mmHg, your blood pressure is ‘120 over 80’.
What do the numbers mean?
Every blood pressure reading consists of two numbers or levels. They are shown as one number on top of the other.
The first (or top) number is your systolic blood pressure. It is the highest level your blood pressure reaches when your heart beats.
The second (or bottom) number is your diastolic blood pressure. It is the lowest level your blood pressure reaches as your heart relaxes between beats.
- If BP is above 150 systolic on at least two occasions you should see your doctor.
- If your blood pressure is above 180 systolic then you should see someone immediately.
- If your blood pressure is below 90 then you should also seek medical attention.
Blood pressure is a range and so don't worry if it changes, throughout the day your blood pressure changes to suit the environment and stress your body is under.