BMI for Indians: why the cut-offs are lower, and what to check alongside it

BMI is weight in kilograms divided by height in metres squared: BMI = kg ÷ m². For a person weighing 70 kg and standing 1.72 m, that is 70 ÷ (1.72 × 1.72) = 70 ÷ 2.9584 = 23.66.

Both inputs are easy to get wrong in ways that change the category. Weigh yourself in the morning, before eating, on a hard floor with the scale on a level surface, wearing minimal clothing — weight taken after a large meal can differ by a kilogram, which is enough to move a borderline reading. Measure height without shoes, heels together against a wall, looking straight ahead, with a flat object against the top of your head. And measure in metres, not centimetres: 172 cm is 1.72, and forgetting the conversion produces a meaningless result.

The squaring is what makes BMI sensitive to error at the extremes. In the example above, understating your height by 3 cm raises the calculated BMI from 23.66 to 24.5 — across a category boundary, from a single measurement mistake.

Some Asian-Indian research uses lower thresholds than the international WHO classification. For example, an ICMR-INDIAB research report defined general obesity as BMI 25 or above. WHO retains its international classification but identifies 23 and 27.5 as additional public-health action points for Asian populations. Risk varies between populations and individuals.

One illustrative Asian-Indian classification uses 23–24.9 as an at-risk or overweight band and 25 or above as obesity. The international classification uses 25 for overweight and 30 for obesity. These are screening thresholds, not diagnoses; different guidelines may use other categories.

BMI cannot see where fat sits, and where fat sits is what drives most of the risk. Indian guidance therefore treats abdominal obesity as a marker in its own right: a waist circumference of 90 cm or more in men, or 80 cm or more in women, indicates central obesity regardless of what the BMI says.

Measure the waist correctly: at the midpoint between the lowest rib and the top of the hip bone, after exhaling normally, with the tape snug against the skin and parallel to the floor. Do not measure at the level of the navel, which is where most people instinctively put the tape and which reads higher. Do not pull the tape tight, and measure at the same time of day when comparing over months.

A waist-to-height ratio above 0.5 is a further simple screen: keep your waist circumference under half your height. These are screening rules, not diagnoses, and they are best read together — a BMI of 22 with a waist of 96 cm is a different picture from a BMI of 22 with a waist of 78 cm.

BMI is a population screening tool that was never designed to assess an individual. Its blind spots are well documented and worth stating plainly.

• It cannot distinguish muscle from fat. A strength-trained athlete with a BMI of 27 may carry less fat than a sedentary person with a BMI of 23, while the number says the opposite.
• It says nothing about fat distribution, which is why waist circumference is required alongside it.
• It is not valid for children and adolescents as a raw number — they need age- and sex-specific percentile charts, since the threshold changes as they grow.
• Pregnancy changes everything: BMI categories do not apply, and gestational weight gain is assessed against a different standard entirely.
• It does not reflect fitness, blood pressure, blood sugar, lipids, sleep quality or family history, all of which carry more weight in a clinical assessment than the index does.

Used honestly, BMI is a trend line and a conversation starter. Tracked every two to three months under the same conditions, it shows whether a change in routine is moving things in the right direction, although no single measure fully describes health.

The value can help start a conversation about health, but it does not establish an individual weight goal. A clinician can interpret it alongside history, measurements and other factors, and advise whether any action is appropriate.

Our adult BMI calculator shows an Asian-Indian example alongside international categories, plus the weight values corresponding to an illustrative BMI band. It processes the inputs locally. The range is not a personal health or weight target; discuss concerns with a qualified clinician.