Why Indians get metabolic risk at lower BMIs

A BMI of 23 can carry real metabolic risk in a South Asian body, risk a standard Western reference range wouldn't flag until 27 or higher. Here's the research behind why, and what's worth measuring instead.

A BMI of 23 reads as "normal" on almost every chart in use. For a South Asian body, that same number can already carry meaningful diabetes and cardiovascular risk, the kind a standard Western reference range wouldn't flag until several points higher. This isn't a fringe theory. It's the conclusion of a dedicated WHO expert consultation, and it's a big part of why so many people are told their weight is fine right up until a blood test says otherwise.

The consultation that changed the range

In 2002, the WHO convened an expert consultation specifically to examine whether a single global BMI cut-off made sense across populations. Their conclusion, published in The Lancet in 2004: the proportion of Asian people at high risk of type 2 diabetes and cardiovascular disease was already substantial at BMIs below the standard overweight threshold of 25 kg/m², with meaningful risk appearing as low as 22 to 25 kg/m² depending on the population.

“The proportion of Asian people with a high risk of type 2 diabetes and cardiovascular disease is substantial at BMIs lower than the existing WHO cut-off point for overweight.”

Why the same number means something different

BMI measures weight relative to height. It says nothing about what that weight is made of. South Asian bodies tend to carry a higher percentage of body fat, and more of it viscerally, around the organs, at the same BMI as other populations, alongside comparatively less muscle mass. Two people can share an identical BMI and carry very different metabolic risk, because the number was never measuring the thing that actually matters.

What's worth measuring alongside it

• Waist-to-height ratio: a simple, better proxy for visceral fat than BMI alone.
• Fasting insulin and HOMA-IR: catch insulin resistance well before weight or glucose shift.
• ApoB or a full lipid panel: particle-level cardiovascular risk that BMI can't see at all.
• Trend over time: a single measurement, of any kind, is a snapshot. The direction is the signal.

None of this means BMI is useless. It means it's a rough starting point, not a verdict, and for a South Asian body specifically, "normal" on a global chart is worth a second look rather than automatic reassurance.