How does my weight affect my health?
Maintaining a healthy weight is an important way to make sure you stay in good health and reduce the chance of developing a number of long-term health problems.
Being overweight increases your risk of developing health problems including coronary heart disease, stroke, type 2 diabetes, osteoarthritis and some types of cancer. If you’re underweight, you may be more likely to develop other health problems, such as osteoporosis.
Am I a healthy weight?
There are several different ways of working out whether you’re a healthy weight. The most commonly used measurement is body mass index (BMI). Your waist circumference and body shape can also indicate whether you may be at a raised risk of developing health problems.
If you’re not sure whether you’re a healthy weight, it’s always best to check with your GP or practice nurse.
Body mass index (BMI) takes into account your weight and height and is, in general, a good indicator of how much body fat you have.
BMI is calculated as: your weight in kilograms divided by the square of your height in metres. To work out your BMI, use our BMI calculator.
Using the BMI system, if your BMI is:
- less than 18.5 – you’re underweight
- between 18.5 and 24.9 – you’re a healthy weight
- between 25 and 29.9 – you’re overweight
- between 30 and 39.9 – you’re obese
- over 40 – you’re morbidly obese (your weight is particularly harmful to your health)
A limitation of the BMI is that it doesn’t apply to everybody. BMI isn’t used for pregnant women or children. A child’s weight changes a lot as they grow, so their age and also their sex is taken into account when working out whether or not they are a healthy weight. BMI can’t be applied to pregnant women as they are gaining weight due to their growing baby.
BMI may also be unsuitable for people with a lot of muscle. For example, athletes may have a BMI over 25 but have very little body fat.
If you belong to a certain ethnic group (for example, if you’re of Asian descent), the BMI ranges above may not be appropriate for you. Speak to your GP for more information.
Where you store fat on your body is an important indicator of whether or not your weight is a risk to your health. Storing fat around your middle (apple-shaped) is thought to be unhealthier than storing it around your thighs and bottom (pear-shaped). If you’re apple-shaped, you’re at a higher risk of developing coronary heart disease and diabetes.
Your waist circumference is strongly related to your risk of certain conditions, including coronary heart disease, diabetes and high blood pressure. 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.
Maintaining a healthy weight
Your weight is determined by the balance between what you eat and drink and how active you are. The energy that your food provides and that you use up walking, running or even sitting still, is measured in calories.
- You will gain weight if you take in more calories than you use up.
- You will lose weight if you use up more calories than you take in.
- You will maintain your weight if you balance the calories you take in with the calories you use.
But what does this mean for you, and what changes can you make if you weigh too much or too little?
If you’re a healthy weight
You should aim to maintain your weight through a combination of eating a balanced diet and doing regular physical activity.
Eating a healthy balanced diet means basing your meals around starchy foods, preferably wholegrain varieties, eating lots of foods high in fibre and eating at least five portions of fruit and vegetables a day. Don’t eat too many foods containing fat and sugar. Try to eat three meals a day, including breakfast, and make sure your portion sizes are appropriate.
Aim to do some physical activity every day. The recommended healthy level of physical activity is 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes on at least five days each week. Alternatively, you can do 75 minutes of vigorous intensity activity.
It’s important that you include at least two weekly activities to build up muscle strength, such as exercising with weights. Try to spend as little time as possible being inactive.
If you’re overweight or obese
Your risk of health problems is higher. Losing weight can be very beneficial for your health. To lose weight, you need to burn off more calories through physical activity than you take in from food and drink. This means eating fewer calories, burning more off or, preferably, both.
Eat a healthy, balanced diet and try to cut down on foods containing fat and sugar. Try to build physical activity into your usual daily routine, for example walking to work instead of driving or taking the stairs instead of the lift.
If you’re underweight
This may be because you don’t take in enough calories or because you exercise a lot. If you have a very restricted diet, you may not be getting enough vitamins and minerals to keep your body healthy. Try to increase your calorie intake through eating a balanced and nutritious diet, in order to gain weight and get back into a healthy weight range for your height.
Unexplained weight loss or being unable to put on weight can sometimes be a symptom of an underlying health problem. If you find it difficult to put on weight or if you have lost a lot of weight quickly, see your GP.