BMI, or body mass index, is one way of measuring whether you’re a healthy weight for your height.
The result gives an indication of whether you’re a healthy weight, and if not, how over or underweight you are. BMI isn’t always the best measure to use because there are other things that you need to take into account when it comes to weight (see our limitations information further down the page). But it can be a useful guide.
Simply enter your details into our calculator to find out what your BMI is and whether you’re a healthy weight.
Calculate your BMI
What your BMI result means
You are in the underweight range, with a BMI score of under 18.5.
Your weight depends on the balance between how much energy (calories) you consume from food, and the amount of energy you use. So try to make sure you’re eating enough calories throughout your day. Aim for three balanced meals a day, making sure you eat enough carbohydrates, with some healthy, nutrient-dense snacks in between. Good examples are unsalted nuts, a pot of yogurt or peanut butter on toast. Talk to your practice nurse or GP for more advice about gaining weight in a healthy way. You may also be referred to a dietitian.
If your GP has any concerns about your health or wants to explore potential reasons for your weight loss, they may refer you for further tests or investigation. If you suffer with an eating disorder, your nurse or GP will be able to support you to gain the right treatment.
What your BMI result means
You're in the healthy weight range, with a BMI score of 18.5-24.9
Good work, it looks like you’re a healthy weight! This will reduce your risk of developing health problems in the future, such as heart disease and type 2 diabetes. Carry on eating a healthy, balanced diet rich in fruit and veg, and low in saturated fat and refined sugars; and exercise regularly.
Throughout life, and especially as you get older, it’s also a good idea to watch out for your waist circumference as this can be another indicator of health risks. Aim to keep it less than 80cm (31.5 inches) if you’re a woman and under 94cm (37 inches) if you’re a man.
What your BMI result means
You're in the overweight range with a BMI score of 25-29.9
Your BMI suggests that you’re overweight, which can increase your risk of health conditions, such as high blood pressure, heart disease and certain types of cancer. The good news is, there are steps you can start taking straightaway to help you lose excess weight in a healthy way and reduce your chance of health problems in the future.
Your weight is determined by how much energy (calories) you consume through food versus how much energy your body uses. Cut down on foods high in fat and sugar, and aim to do at least 30 minutes of physical activity on five days each week. Being as physically active as possible is fantastic for your health and will keep your weight down. Why not track how many steps you take each day? Aim for 10,000 as a goal. Or make a pledge to have a brisk walk around the block before breakfast or on your lunch break.
What your BMI result means
You're in the obese weight range with a BMI score of over 30.
If you fall into this category of BMI, you’re at a high risk of health conditions, such as heart disease, high blood pressure, cancer and type 2 diabetes. There are different grades of obesity and the greater your BMI, the greater your risk of these health problems.
It’s important that you try to lose weight. You’re weight is determined by how much energy (calories) you consume through food versus how much energy your body uses. Cut down on foods high in fat and sugar, and aim to do at least 30 minutes of physical activity on five days each week. Starting exercise if you’ve not done much before can feel daunting, but start small. Walk to the corner shop, or walk your children to school. Take the stairs over the escalator or use your lunch break to get outside and stretch your legs. Talk to your practice nurse or if you’re heavily overweight for advice and more information.
Although, in general, BMI is a useful measure of whether or not you’re a healthy weight, it isn’t appropriate for everyone. There are a number of groups of people where a BMI result should be considered carefully, or where it may not even be appropriate to use at all.
- Girls and boys develop differently and have different amounts of body fat at different ages. Therefore, a child’s age and sex are taken into account when looking at their BMI.
- As we age, we tend to have more body fat and less muscle, so BMI may underestimate body fat in older people.
- Athletes and people with a lot of muscle may have a high BMI but actually not have much body fat.
- Pregnant women gain weight as a result of their developing baby. However, it’s still preferable to have a healthy BMI before becoming pregnant to reduce health risks to both you and your developing baby.
- Certain ethnic groups, such as black or Asian, are at risk of certain health problems at a lower BMI than others. Speak to your GP or practice nurse for more information.
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