Waist-to-hip ratio is touted as 'the new BMI' for tracking health – but is it reliable?

I'm somewhat ashamed to say that I don't own any wearable tech. I can absolutely see the appeal – the idea that you can track everything from your sleep to your stress levels and use that data to make better decisions about your health – but I've just never felt the need to quantify things I already have a sense of. I usually know when I've slept badly (hello eye bags), or when I'm feeling run down, and I've always preferred to trust that instinct rather than check an app.

Admittedly, I'm not completely removed from the world of health metrics. At my gym, I've been having semi-regular InBody scans – where I stand barefoot on a set of scales, holding onto two handles, while the machine works out my body composition via low-level electrical signals. A few minutes later, a report lands on my phone with a breakdown of everything from body fat and muscle mass to visceral fat and my waist-to-hip ratio.

I've been doing the scans every month for the past year and, for the most part, the results have been reassuring. My muscle mass has increased; my body fat has come down – all the markers you’d hope to see moving in the right direction if you're training consistently and eating relatively well. But there's one measurement that hasn't shifted at all: my waist-to-hip ratio, which has stayed firmly in the red.

And it's that metric that’s stuck in my head. While I have a rough understanding of what body fat percentage or muscle mass means in practical terms, the waist-to-hip ratio feels a bit more abstract. If everything else is improving, how much does it matter if that one measurement isn't? And is waist-to-hip ratio actually a useful marker of health?

What is the waist-to-hip ratio?

Waist-to-hip ratio (WHR) is considered a type of biomarker - a measurable indicator of what is happening inside your body. To find out your WHR, you simply measure your waist circumference (the smallest part of your waist) and your hip circumference (the fullest part of your buttocks) and divide your waist measurement by your hip measurement. As a general guideline, women should look for a number below 0.85 and men 0.90.

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What does the waist-to-hip ratio indicate?

So, we know it's a biomarker – but what can it actually tell us? "Unlike body weight or BMI, it gives a sense of fat distribution, which turns out to matter more metabolically than total fat mass alone," explains April Morgan, Head of Nutrition at supplement brand ARTAH. In particular, a higher ratio is often used as a proxy for visceral fat – the type stored around the organs and more strongly linked to insulin resistance, systemic inflammation and long-term cardiometabolic risk. 

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"We can track waist-to-hip ratio using the InBody scan, but we don’t really focus on it," says Fenton Hancock, strength and conditioning coach and founder of HUB Fitness, a gym based in Hitchin. "It can highlight a potential correlation with higher body fat and future health risk, but it doesn't give us the full picture. Context is everything."

Part of the issue is that WHR doesn't distinguish particularly well between different types of tissue. It won't tell you how much of your weight is muscle versus fat, nor can it reliably separate visceral fat from subcutaneous fat – the latter being the fat that sits just beneath the skin and is far less metabolically concerning.

It also doesn't account for body shape. "Someone with more developed glutes, or naturally wider hips, could have a very different reading," Hancock explains. "We see plenty of clients who are fit, strong and healthy, but still fall into the 'red' category for waist-to-hip ratio." 

Morgan agrees that it has its limitations. "It's still a fairly blunt tool," she says. "It doesn't capture the full metabolic picture, and there are cases where someone can have a 'healthy' ratio but still have underlying metabolic issues."

In other words, while waist-to-hip ratio can offer a useful snapshot (particularly at a population level) it’s not something most experts would rely on in isolation. As Hancock puts it: "If your strength is improving, your cardiovascular fitness is increasing and your body composition is moving in the right direction, that's what we’d prioritise. One number on its own doesn’t define your health."

Can you change your waist-to-hip ratio? 

It is possible to influence the ratio over time – particularly by reducing body fat around the stomach area. Building muscle around the glutes and hips may also help alter the measurement, though Hancock notes this tends to happen far more gradually. "Building half a kilogram of pure muscle mass can take over a year," he says, whereas changes to waist circumference through fat loss can happen in a matter of weeks.

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Still, both experts are keen to stress that WHR isn't something to become overly fixated on. "You could be lean, very fit, have a good amount of muscle mass and your waist-to-hip ratio could still flag as red," Hancock explains. Ultimately, it’s only one marker of health – and not necessarily the most important one.

What impacts where you store fat?

"Fat distribution is highly heritable," says Morgan, meaning some people are predisposed to storing weight around the stomach, while others carry it around the hips and thighs. Hormones also play a significant role, particularly for women. "During reproductive years, oestrogen promotes fat storage around the hips and thighs," says Morgan. "But during perimenopause and menopause, declining oestrogen levels are associated with a redistribution of fat towards the abdomen."

Lifestyle factors can influence things, too. Chronic stress and elevated cortisol levels have both been linked to increased abdominal fat storage, while poor sleep, a sedentary lifestyle and diets high in ultra-processed foods may also contribute. 

"Resistance training and aerobic exercise can help reduce visceral fat," Morgan adds, alongside prioritising protein, fibre, sleep and stress management. It's clear then that where we store fat is rarely down to one single factor and it's far more nuanced than a simple measurement can capture.

What should you look at instead?

While waist-to-hip ratio can offer a useful snapshot, both experts agree it makes far more sense to look at the bigger picture rather than fixating on one standalone number. For Hancock, the most meaningful indicators of long-term health are often far less aesthetic. "We're mainly looking at trends over time," he explains. "If someone's strength is improving, their cardiovascular fitness is increasing and their body composition is moving in the right direction, that's what matters most."

Markers such as muscle mass, visceral fat levels, cardiovascular fitness and blood markers such as cholesterol, blood pressure and blood glucose can all offer a more rounded picture of metabolic health. Hancock also points to VO2 max (a measure of how efficiently the body uses oxygen during exercise) as one of the strongest indicators of longevity, alongside grip strength, which has been linked to healthy ageing in research. “Don't panic if your waist-to-hip ratio is off," he says. "Look at the whole picture, not just one score."