Healthy weight

A combination of factors determines our weight, and that's why it's difficult to set an exact ideal weight that applies to everyone.

It's important to remember there's a range of healthy body weights. Aiming to keep within this means an end to aspiring to one magic weight you think you should be.

Many people have a distorted perception of what constitutes a healthy body weight. We're surrounded by images of celebrities, many of whom are underweight. Comparing yourself with these images isn't helpful. But comparing yourself to friends and family isn't that useful either, because as obesity becomes more common our perception of 'average' weight may in fact be too heavy.

It's important to make an objective assessment of your size. Looking at yourself in the mirror isn't a good way to assess whether you're a healthy weight.

How do I know if I'm a healthy weight?

There are a number of ways you can work out if you're within a healthy weight range. You need to get an accurate idea because it's easy to underestimate or overestimate your own weight.

Body mass index

You can check your body size using the body mass index (BMI), which assesses your weight in relation to your height.

Work out your BMI with our calculator, with both metric and imperial results.

Waist circumference

Another method of assessing whether you're a healthy weight is to measure your waist.

This gives an indication of how much fat is stored around your middle. Excess fat in this area increases your risk of heart disease and diabetes.

Body fat

You can measure the amount of fat in your body using scales designed for this purpose, often called body fat analysers. These pass a small, safe electrical signal through your body.

Lean tissue, such as muscle, and blood contain water and act as conductors of the electrical signal, while fat resists it. The greater the resistance, the more body fat you have.

Body fat is only one aspect of health.

Your GP can advise whether additional measurements such as blood pressure, resting heart rate, blood cholesterol, and fat and glucose tests are necessary.

Are you overweight?

If your BMI and waist circumference indicate you're overweight, changes to your lifestyle could help to control your weight. Think about how you can make changes to your diet and physical activity over the long term.

For more advice, see Do you need to lose weight?

Are you underweight?

Not weighing enough can also put your health at risk. If you're underweight because of a restriction of your diet, you're at risk of a number of nutritional deficiencies.

Young women especially are at risk of anaemia (a lack of iron), while insufficient calcium can lead to osteoporosis in later life. Amenorrhoea (missing menstrual periods) is also common among women who are underweight, and it can lead to infertility.

For more information, see Do you need to gain weight?

Are you a healthy weight but unhappy?

If your weight lies within the healthy range but you're unhappy with your shape, you'll probably derive more benefits from a supervised exercise programme than by restricting your diet.

This will improve your fitness, help to tone specific muscle groups and enhance your overall health and wellbeing.

Dr Susan Jebb last medically reviewed this article in June 2007.