Free tool · Reviewed July 25, 2026
Waist-to-hip ratio & Body Roundness Index
Two measurements that tell you what BMI cannot — where the weight actually sits, and whether it is moving when the scale says it isn't.
Key takeaways
- Waist-to-hip ratio is waist divided by hips — the WHO treats 0.90 or above in men and 0.85 or above in women as abdominal obesity.
- It captures something BMI cannot: where fat sits. Two people at an identical BMI can have very different waist-to-hip ratios and different metabolic risk.
- Body Roundness Index estimates central body volume from waist and height. It has no FDA- or WHO-endorsed cut-offs, so it is a number to track over time, not a pass/fail line.
- On a GLP-1, waist often keeps shrinking through a weight plateau — measuring it is how you see progress the scale is hiding.
- Measure over bare skin, tape level, at the end of a normal breath out. Pulling the tape tight is the most common cause of a misleading number.
At the narrowest point
At the widest point
For BRI only
Measure over bare skin with a flexible tape, level to the floor, at the end of a normal breath out. Pulling the tape tight is the most common source of a misleading result.
Nothing you type here is stored or sent anywhere — the arithmetic runs in your browser. These are screening measures, not a diagnosis.
Why this matters more than usual on a GLP-1
The most common reason people abandon a GLP-1 that is working is a scale that stops moving. Weight is a single number covering fat, muscle, food and fluid at once, and during a plateau those can shift in opposite directions while the total holds still.
Waist circumference moves independently of that noise, which makes it the honest progress signal during exactly the weeks people are most tempted to quit. If your waist is falling and the scale isn't, that usually means you are losing fat while holding onto muscle — which is the goal, and the reason what you pay per month buys more than a number on the scale. For the muscle side of it, see GLP-1s and muscle loss.
Compare GLP-1 providers on total monthly cost
SponsoredIf these numbers put you in the range where a GLP-1 is discussed, this is what the options actually cost. US-licensed providers — we compare and link, we never sell medication.
Advertising disclosure: we may earn a commission if you sign up through these links, at no extra cost to you — it never affects our rankings. How we make money
Common questions about waist-to-hip ratio and BRI
What is a healthy waist-to-hip ratio?
The World Health Organization uses 0.90 for men and 0.85 for women as the threshold for abdominal obesity — at or above those figures, the measurement indicates fat concentrated around the middle, which carries more metabolic risk than the same weight distributed elsewhere. Below them is generally considered lower risk, though no single measurement decides health on its own.
Is waist-to-hip ratio better than BMI?
It measures something different rather than something strictly better. BMI compares weight to height and cannot tell where that weight sits; waist-to-hip ratio captures distribution, which is why two people with the same BMI can carry very different risk. Clinically the two are used together — and note that BMI, not waist ratio, is the criterion insurers apply to GLP-1 coverage.
What is Body Roundness Index (BRI)?
BRI estimates how much of your body volume is concentrated centrally, using waist circumference and height in a geometric formula published by Thomas and colleagues. It is newer than BMI and has drawn research interest as a predictor of metabolic risk, but there are no regulator-endorsed cut-off values, so a specific BRI number is best read as a baseline you track rather than a category you fall into.
Why is my waist shrinking but the scale not moving?
This is common on a GLP-1 and it is usually a good sign, not a stall. Weight can hold steady while body composition changes — particularly if you are getting enough protein and doing any resistance training, since preserved muscle offsets lost fat on the scale. Waist measurement is the cheapest way to see that progress. It is also why measuring only weekly weight can talk people into quitting something that is working.
Waist-to-hip thresholds are the World Health Organization values for abdominal obesity. BRI uses the published Thomas et al. formula and has no regulator-endorsed cut-offs. These are screening measures, not a diagnosis — general information, not medical advice.