CHOICE guide to body numbers

We run through the top five numbers and what you should be aiming for as a healthy adult.
 
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  • Updated:28 Nov 2007
 

01.Introduction

Please note: this information was current as of November 2007 but is still a useful guide today.


There are lots of numbers and measurements used to describe health. We explain what they all mean. We run through the top five numbers and what you should be aiming for as a healthy adult. Knowing them — and whether they need to go up or down — could save your life.

Blood pressure

Blood pressure is the force of the blood pushing against the walls of the arteries as the heart pumps it round your body. It’s always given as two numbers. The top number — systolic pressure — indicates the pressure in the arteries when the heart beats, pumping blood. The bottom number — diastolic pressure — represents the pressure as the heart relaxes between beats.

High blood pressure, or hypertension, is sometimes called the silent killer because it usually has no symptoms — you can have high blood pressure and feel perfectly well. Ongoing, it can lead to serious problems like heart attack, stroke and kidney disease.

Smoking, physical inactivity, overweight/obesity, poor nutrition and excessive alcohol consumption can all increase your risk of hypertension.

Aim for

  • Less than 120/80 mmHg
    In general, lower is better, although very low blood pressure can sometimes be a cause for concern and should be checked out by a doctor.

Check it

  • Every two years from age 18 if it’s 'normal'. More frequently if you have a personal or family history of hypertension, stroke or heart attack.

Cholesterol

Cholesterol is a lipid (a fat-like substance) that occurs naturally in the body. It’s essential for you to function properly, but your body generally makes all it needs. Eating too much saturated fat leads to excessive cholesterol in your blood which can increase your risk of heart disease and stroke. Smoking, hypertension and being overweight are also risk factors. Like high blood pressure, high blood cholesterol doesn’t produce any symptoms and many people first learn they have it only when they have a heart attack or stroke.

Cholesterol is transported in the blood by carriers called lipoproteins, of which there are two main types: low-density lipoprotein (LDL), usually referred to as 'bad' cholesterol because it can clog up your arteries; and high-density lipoprotein (HDL), known as 'good' cholesterol because it helps to take cholesterol out of the bloodstream.

The lipid profile from a fasting blood test gives you a breakdown of total cholesterol, HDL, LDL and triglycerides (a form of fat storage in the body) in your blood. A finger prick cholesterol test, such as the type offered in some pharmacies for around $10, gives you total cholesterol only.

Certain lipid ratios are risk factors for some conditions — having high triglycerides and low HDL and/or high total cholesterol is a risk factor for pre-diabetes, for example, so it’s useful to know all the numbers. 

Aim for 

  • Total cholesterol below 4 mmol/L
  • LDL below 2 mmol/L
  • HDL above 1 mmol/L
  • Triglyceride below 1.5 mmol/L

The target levels may be more lenient if you’re not in a high risk group (someone with heart disease, diabetes or a family history of high cholesterol, for example). But generally any lowering of total and LDL cholesterol levels and any raising of HDL cholesterol can be beneficial, even if you’re not reaching the target.

Check it

  • Every five years from age 45. More frequently if you’re in a high risk group.

Blood glucose

Levels of glucose in your blood are controlled by insulin, and when your body’s insulin isn’t working effectively this can result in low blood glucose (hypoglycaemia) or high blood glucose (hyperglycaemia).

Chronic hypoglycaemia can lead to brain and nerve damage. Chronic hyperglycaemia indicates diabetes which, if left untreated, can cause progressive damage to body organs such as the kidneys, eyes, heart, blood vessels and nerves.

Nearly one in four adults over the age of 25 years has either diabetes or a condition known as pre-diabetes (impaired glucose metabolism). People with pre-diabetes are more likely to get type 2 diabetes and are at risk of heart disease.

A fasting blood glucose test can determine if your blood glucose level is within a healthy range.

Aim for

  • 3.0 to 5.4 mmol/L

Check it

  • Every three years from age 55. Start younger and check more frequently if you have a high risk of type 2 diabetes (you’re over 45 and obese, for example).

Waist circumference

Waist circumference is a measure of abdominal fat. Having fat around your abdomen ('apple' shape), regardless of your body size, has been linked to an increased risk of diseases such as heart disease and type 2 diabetes. Fat predominantly deposited around the hips and buttocks (‘pear’ shape) doesn’t appear to have the same risk.

Aim for

  • Less than 94cm (men), 80cm (women)

Check it

  • As often as you like — all you need is a tape measure. Measure your waist at its narrowest point while standing up with your stomach relaxed.

BMI

Body mass index (BMI) is a measure of your weight relative to your height. It gives an approximate measure of your total body fat and indicates whether you’re overweight or obese. If you are, it’s a risk factor for other diseases and conditions such as diabetes, heart disease, hypertension, osteoarthritis and some cancers.

But BMI has its limitations:

  • It may overestimate body fat in pregnant women, athletes and others who have a muscular build.
  • It may underestimate body fat in the elderly and others who have lost muscle mass.
  • It can be misleading in children as body fat changes as they grow, and girls and boys also differ in their body fat as they mature.
  • For some ethnic groups the cut-offs for being overweight and obese are different. They’re lower for Chinese, Indian and Malaysian people, for example.

Aim for

  • 18.5 to 24.9

Less than 18.5 is underweight, 25 to 29.9 is overweight, 30 or higher is considered obese.

Check it

  • Now. Divide your weight (in kilograms) by your height (in metres) squared. A person who’s 1.65m (165cm) tall and weighs 60kg, for example, has a BMI of 60 ÷ (1.65 x 1.65) = 22, which is in the normal range.
 
 

 

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