Low BMI: understanding it and where to find help
This tool explains what a low BMI means and where to find help. You can enter a height and a weight, or leave the boxes empty to read the information only. It never shows a weight to aim for.
General information, not medical advice. This result does not replace a doctor. If in doubt or if you have symptoms, see a health professional.
Result
18BMI
- This BMI is below 18.5, the lower WHO adult reference value. A low BMI can have many causes. If you have lost weight without meaning to, think a lot about food or your weight, or feel tired, talk to a doctor.
- A family doctor (GP) is a good first, non-judgemental contact to talk about weight, appetite or eating.
- Eating disorder charities, such as Beat in the UK or the Butterfly Foundation in Australia, inform and guide the people affected and those close to them.
- If you feel unwell, are in danger or have suicidal thoughts, call your emergency number now (112, 999 or 911 depending on the country).
Inputs
- Height (optional)
- 170
- Weight (optional)
- 52
How it is calculated
BMI = weight (kg) ÷ height (m)².
Result
BMI
How it is calculated
- BMI = weight (kg) ÷ height (m)².
- 18.5 is the lower WHO reference value for adults. It does not apply to children and teenagers, nor during pregnancy.
- On purpose, no weight is calculated: the tool is for understanding and finding help, not for setting a goal.
Example
Height 170 cm, weight 52 kg: BMI 18.0, below the lower reference value of 18.5, with the help resources.
Good to know
- BMI measures neither body composition nor health; an eating disorder can exist at any BMI.
- Under 18, BMI is read on growth charts with a professional.
- This tool does not replace medical advice.
Sources
- WHO, Body mass index (BMI), adult classification
- NICE, Eating disorders: recognition and treatment (NG69), 2017
- Beat, UK eating disorder charity (beateatingdisorders.org.uk)
Frequently asked questions
What is this tool used for?
This tool explains what a low BMI means and where to find help. You can enter a height and a weight, or leave the boxes empty to read the information only. It never shows a weight to aim for.
How is the result calculated?
BMI = weight (kg) ÷ height (m)².
What should I check before using the result?
BMI measures neither body composition nor health; an eating disorder can exist at any BMI.