Is BMI Actually Useful? What Your Doctor Wishes You Knew About Healthy Weight

Every corporate health screening I conduct includes BMI measurements. It's fast, it's cheap, and it's universally understood. An employee steps on a scale, I measure their height, and a number appears that's supposed to tell us something meaningful about their health.

But here's the thing: BMI is both useful and misleading — often at the same time. And the way it's commonly interpreted, especially in workplace health settings, can cause as many problems as it solves.

As an Occupational Health Doctor, I think it's important to be honest about what BMI can and can't tell you, and what better alternatives are available. Because the conversation around weight and health is evolving rapidly, and the science has moved well beyond a single number.

What BMI actually is (and isn't)

Body Mass Index is a simple mathematical formula: your weight in kilograms divided by the square of your height in metres. It was developed in the 1830s by a Belgian mathematician — not a physician — as a tool for studying population-level obesity trends. It was never designed to assess individual health.

That distinction matters. BMI works reasonably well when you're looking at thousands of people and trying to identify broad patterns. It falls apart when you try to use it as a diagnostic tool for individuals, because it doesn't distinguish between muscle mass and fat mass, it doesn't tell you where your fat is distributed, and it doesn't account for differences in body composition between ethnic groups, age groups, or sexes.

Where BMI gets it right

At the population level, higher BMI does correlate with increased risk of Type 2 diabetes, cardiovascular disease, certain cancers, and all-cause mortality. The correlation is real and well-established. If your BMI is above 30, your statistical risk of developing these conditions is elevated — and that's worth knowing.

Where BMI gets it wrong

A muscular athlete and a sedentary office worker can have the same BMI but wildly different health profiles. A person with a "normal" BMI of 23 can have dangerous levels of visceral fat if they carry that weight around their abdomen. And crucially for Malaysian and Asian populations, the standard BMI cutoffs developed primarily from European data tend to underestimate metabolic risk — Asian individuals develop insulin resistance and cardiovascular risk at lower BMI thresholds than their Western counterparts.

Better measures than BMI

If BMI alone isn't enough, what should you be looking at? The answer depends on the context, but there are several measures that add significantly more clinical value.

Waist circumference

This is arguably more important than BMI for predicting metabolic disease. Abdominal fat — the fat that sits around your organs (visceral fat) — is metabolically active in a way that subcutaneous fat (the fat under your skin) is not. It drives inflammation, insulin resistance, and cardiovascular risk. A waist circumference above 90 cm for men or 80 cm for women (using Asian-specific cutoffs) is associated with significantly elevated risk, regardless of what the BMI number says.

Waist-to-height ratio

An even simpler screen: if your waist circumference is more than half your height, you're likely carrying excess abdominal fat. This ratio performs better than BMI across different ethnic groups and body types, and it's something anyone can check at home with a tape measure.

Blood markers

Ultimately, the most accurate way to assess metabolic health is through blood tests — fasting glucose, HbA1c, lipid profile (particularly triglycerides and HDL cholesterol), and liver enzymes. These tell you directly what's happening inside, regardless of what the scale says. I've seen employees with a "healthy" BMI of 22 who have pre-diabetic glucose levels and elevated triglycerides, and employees with a BMI of 28 whose blood work is textbook normal.

Why this matters for workplace health

In corporate wellness programmes, BMI is often the primary (sometimes only) metric used to assess employee health risk. The problem is that this creates two types of errors: false reassurance for metabolically unhealthy employees with a normal BMI, and unnecessary alarm for healthy employees who happen to be heavier.

A better approach — and the one I recommend to employers — is to use BMI as one component of a broader metabolic risk assessment that includes waist circumference and basic blood work. This catches the people BMI misses and avoids unfairly flagging those it shouldn't.

It also helps to frame workplace wellness programmes around health behaviours rather than weight targets. Encouraging employees to eat better, move more, sleep well, and manage stress will improve their metabolic health regardless of whether their weight changes — and it avoids the moralising and stigma that often accompanies weight-focused messaging.

A word on weight stigma

I want to address this directly, because it comes up in my practice often. Weight is a sensitive subject, and the way it's discussed in workplace settings can have real consequences for employee morale and mental health. I've seen well-intentioned health screening programmes inadvertently shame employees by focusing too heavily on BMI categories without context.

The evidence is clear that weight stigma is harmful — it increases stress, discourages health-seeking behaviour, and can worsen the very health outcomes it claims to address. A good workplace health programme focuses on empowering employees with knowledge and support, not labelling them with a number.

Dr. Kirath Sidhu (Dr. Harkirath Singh Harbans Singh) is a registered Occupational Health Doctor affiliated with ASP Medical Group. He provides corporate health screenings, metabolic risk assessments, and HRDC-certified workplace wellness training to employers across Malaysia.