Last updated 21 October 2026
Where we look first
- NHSHealth A to Z and the NHS BMI calculator
- NICE NG246Overweight and obesity guideline, 2025
- UK Chief Medical OfficersPhysical activity and alcohol guidelines
- SACNScientific Advisory Committee on Nutrition
We also use GOV.UK collections (such as drink drive limits and physical activity guidelines), the Food Standards Agency, and peer reviewed research for widely used equations, named on the page (for example Mifflin St Jeor for resting energy).
What a link does not mean
Linking to an NHS or GOV.UK page does not mean the NHS or government endorses this site. It means you can read the same public guidance we used.
Methods without a single public page
Some fitness tools use established formulas without a tidy public web page. Then we describe the method on the calculator page, cite the paper, and keep the limits visible.
Keeping sources current
Every number was last checked on 21 October 2026. If guidance changes, we update the number in one place and every page follows. Found a broken or outdated link? Please tell us through the corrections page.