Checking your body mass index
You can check whether you are a healthy weight by working out your body mass index (BMI).
You do this by taking your weight (in kilograms) and dividing it by your height (in metres) squared. So, if you weigh 65 kilograms and are 1.73 metres tall, you would have a BMI of 65 (1.73 x 1.73) equals 21.7.
You can calculate your BMI using the BMI calculator on the NHS Choices website.
As a guide, for most adults a BMI of:
- 18.5 - 24.9 is ideal
- under 18.5 is underweight
- 25 - 29.9 is overweight
- 30 - 39.9 obese
- 40 or more is very obese
These ranges are only for adults. BMI is interpreted differently for children. If you're concerned about your child's weight, seek advice from your GP.
If your BMI is 25 or more, you should think about losing weight. Being overweight or obese can increase your risk of health problems
If your BMI is less than 18.5, you may want to talk to your GP about gaining weight. Being underweight can also increase your risk of health problems, such as:
- brittle bones
- absent periods in women
- iron deficiency anemia
Accuracy of BMI
As well as measuring your BMI, healthcare professionals may take other factors into account when assessing if you're a healthy weight.
Muscle weighs more than fat. Very muscular people, such as heavyweight boxers, weight trainers and athletes, may be a healthy weight even though their BMI is classed as obese.
Your ethnic group can also affect your risk of some health conditions. For example, adults of Asian origin may have a higher risk of health problems at BMI levels below 25.
You should not use BMI as a measure if you're pregnant. Get advice from your midwife or GP if you're concerned about your weight.
What is obesity?
Healthcare professionals use the words 'obese' and 'obesity' as clinical terms to indicate your increased risk of health problems. They do not use these terms to describe what you look like.
More information and advice on how to achieve a healthy weight is available on the Choose to live better website.
If you intend to go on a healthy eating plan to achieve gradual weight loss, you may want to seek advice from your GP beforehand. They can offer you help, support and advice before you start.
Online tools are also available to help you set achievable goals and develop a plan to make healthy lifestyle choices.
Talk to your GP before starting a weight loss programme if you have a long-term health condition, such as type 2 diabetes or heart failure.
You should make sure that you eat a healthy, balanced died to help maintain a healthy weight.
A healthy diet contains:
- plenty of starchy foods like bread, rice, pasta, breakfast cereals, potatoes and sweet potatoes - look for higher fibre versions where possible (like wholemeal bread or pasta)
- at least five portions of a variety of fruit and vegetables daily
- moderate amounts of dairy products (or alternatives) - look for low fat versions where possible
- moderate amounts of meat, fish or alternatives like eggs, beans, peas and lentils - look for lower fat versions where possible
- the occasional treat (foods that are higher in fat, salt or added sugar)
- little salt - always read the label
More information on healthy diet can be found at the link below:
Find ways of increasing your activity which are realistic for you.
This doesn't have to mean going to the gym or taking up sport – many people find it suits them better to go for a regular walk or join a dance class.
As an adult you should aim to be active on five or more days of the week:
- 30 minutes of activity will have general health benefits and improve your fitness
- increase activity to at least 60 minutes to help you lose weight and stop weight going back on