Why assess your body composition?
Overweight and obesity increase the risk of many chronic conditions — type 2 diabetes, cardiovascular disease, certain cancers, joint problems. Identifying a high BMI or an increased waist circumference early makes it possible to act on modifiable factors before complications appear.
Two complementary measurements, not just one
Body mass index (BMI) — weight divided by height squared — remains the World Health Organization's reference measure for classifying body composition into six tiers, from underweight to class III obesity. But BMI does not distinguish fat mass from muscle mass, and two people with the same BMI can have very different fat distribution. This is why health authorities recommend always pairing it with waist circumference, which more directly reflects abdominal fat and the associated cardiometabolic risk. This tool always provides both measurements, never BMI alone.
Thresholds to nuance by background and age
The thresholds used here are those established for the general population. Two important nuances, documented in the scientific literature, are worth knowing:
- South Asian descent: metabolic risk rises at a lower BMI in this population — around 23 kg/m² for overweight and 27 kg/m² for obesity, versus 25 and 30 in the standard thresholds used by this tool.
- People over 65: the BMI range considered normal generally shifts a little higher, around 27 kg/m² — a slight degree of overweight may even play a protective role against frailty at this age.
This tool deliberately stays in its standard version, with no separate branch for these situations: keep these nuances in mind when interpreting your result, and discuss them with your doctor if they apply to you.
The link with cardiovascular risk and diabetes
BMI and waist circumference are also direct input factors for other tools on this site: waist circumference, for example, is part of the FINDRISC calculation used by our "Am I at risk of diabetes?" tool. If your result indicates overweight or obesity, our "What is my cardiovascular risk?" and "Am I at risk of diabetes?" tools let you go further.
