United Kingdom
Change

Support and offers for individual members and customers

Health Information

Healthy weight for adults

Published by Bupa's health information team, September 2008.

This factsheet is for people who are concerned about their weight, or who would like information about maintaining a healthy weight.

Maintaining a healthy weight is an important way to make sure you stay in good general health and to reduce the likelihood of developing a number of long-term health problems.

About healthy weight for adults
Overweight/obese
Underweight
Maintaining a healthy weight
When to change your lifestyle
Questions and answers
Related topics
Further information
Sources

About healthy weight for adults

A measurement called body mass index (BMI) is usually used to work out if someone is underweight, a healthy weight, or overweight. BMI takes into account your weight and height and is, in general, a good indicator of how much body fat you have. This is a key factor as to whether or not your weight is likely to affect your health. To work out your BMI accurately and easily, see our BMI calculator.

Using the BMI measurement system, if you have a BMI of:

less than 18.5 - you're classed as underweight
in the range 18.5 to 24.9 - you're classed as being a healthy weight
in the range 25 to 29.9 - you're classed as overweight
in the range 30 to 39.9 - you're classed as obese
over 40 - you're classed as morbidly obese (morbidly obese means that the amount you're overweight is particularly harmful to your health)

Limitations of BMI

BMI doesn't apply to everybody. If you have a lot of muscle, you may have a BMI over 25 but very little body fat. Similarly, if you have very little muscle, you may still have too much body fat, even though your BMI is in the healthy range.

Ethnic groups

If you belong to a certain ethnic group (for example, if you're of Asian descent), the BMI ranges specified previously may not be appropriate for you. You should talk to your GP about your BMI.

Pregnancy

Your BMI is important if you're trying to get pregnant (low and high BMI are both associated with fertility problems), but once you're pregnant or breastfeeding you shouldn't use BMI to work out if you're a healthy weight.

Children

BMI isn't useful for monitoring the weight of children because their bodies change so much as they grow (for example, babies naturally have much more body fat than toddlers). When your child is weighed, his/her weight will be plotted on a special graph which takes into account gender and age. The location of your child's weight on this graph will show if he/she is a healthy weight or not.

Body shape

Where you store fat on your body is also an important indicator of whether or not there is a risk to your health. If you carry fat around your middle (you're a characteristic 'apple' shape), you're at more risk of developing high blood pressure, coronary heart disease, high cholesterol and diabetes. Your health may be at risk if you're a man with a waist measurement of 94cm (37 inches) or more, or a woman with a waist measurement of 80cm (32 inches) or more. The risks to your health are lower if you carry fat around your bottom and thighs ('pear' shaped).

Overweight/obese

The UK population is getting fatter - the number of obese people has tripled since 1980. Currently around two-thirds of women and three-quarters of men in the UK are either overweight or obese.

You will gain weight if you take in more energy (calories) than you use up.

You're more likely to be overweight if you have a family history of being overweight or obese, if you don't do any physical activity, or if you're stopping/have recently stopped smoking. In less than one in 100 people there is a medical reason for obesity (such as a thyroid problem).

Complications

Being overweight increases your risk of developing health problems such as heart attack, stroke, type 2 diabetes, high blood pressure and some types of cancer. Excess weight also makes arthritis more likely and can make breathing and sleeping difficult.

If you're an overweight woman, you're more likely to have difficulty getting pregnant and are at more risk of having problems during your pregnancy.

If you're an overweight man, you're at an increased risk of impotence and infertility (poor sperm quality).

The more overweight you are, the more likely you are to have health problems.

Underweight

In most cases, being underweight is a result of a poor diet or lifestyle. Making some simple changes in the amounts and types of food you eat will help you put on weight and return to a healthy weight.

Weight loss or an inability to put on weight can sometimes be a symptom of an underlying health problem (such as type 1 diabetes or infection). If you find it difficult to put on weight, or if you lose a lot of weight quickly, you should see your GP. To find out why you're underweight, your GP will ask about your symptoms and examine you. He/she may also ask you about your medical history.

Complications

If you're underweight for a long time you may be more likely to develop long-term health problems, such as osteoporosis and damage to your heart.

Underweight women often have no menstrual bleeding (amenorrhoea) and may have difficulty getting pregnant. Underweight men are likely to have poor semen sperm quality.

Maintaining a healthy weight

You can achieve a healthy weight by eating a balanced diet, only drinking alcohol in moderation and being regularly physically active.

Healthy eating

To maintain a healthy weight you should aim to eat a varied, balanced diet including all the major food groups:

starchy foods
fruit and vegetables
dairy foods
meat, fish and other non-dairy sources of protein (such as beans)
fat and sugar

Physical activity

Keeping physically active is an important way of staying healthy and maintaining a healthy weight. Aim to do at least 30 minutes of moderate physical activity on at least five days a week. Moderate activity should make your heart beat faster, make you feel slightly warm and a little out of breath. If you're not sure if you're doing enough/the right sort of physical activity, talk to your GP. To make sure you're getting enough exercise you could:

walk or cycle to work, the shops or on the school run instead of taking the car
always use the stairs instead of the lift or escalator
go to the gym, a fitness class, swimming or any other exercise (such as tennis, badminton etc) two or three times a week

Many people spend a lot of their leisure time watching television, surfing the internet and playing video games, all of which involve little physical activity. Try to use some of your leisure time to keep active. For example, you could go for long walks, do some gardening or learn to dance.

When to change your lifestyle

If you're underweight and you have been restricting your diet or exercising a lot, you should aim to gain weight and get back into the normal weight range for your height. Also, if you have a very restricted diet you may not be getting enough vitamins or minerals to keep your body healthy. If you're underweight and not sure if you should be trying to put on weight or not, speak to your GP.

If you're a healthy weight (BMI 18.5 to 24.9), you should aim to maintain your weight through a combination of healthy diet and physical activity. Don't be tempted to try to get into the underweight category.

If you're overweight (BMI 25 to 29.9), obese (BMI 30 to 39.9) or morbidly obese (BMI over 40) your risk of health problems is high and it's important that you try to lose some weight. You need to burn off more calories through physical activity than you take in from food and drink. This means tipping your energy balance by eating fewer calories (fatty and/or sugary foods and drinks), burning more off or, preferably, both. Ask your GP for advice on how to change your diet and increase your activity levels to help you lose weight.