Do You Know Your Waist-To-Height Ratio? Why It May Be a Better Predictor of Heart Risk Than BMI

You know the drill at your annual physical. One of the first things you do once you’ve made it into the exam room is step on the scale. And if your doctor doesn’t share your body mass index (BMI) with you right then, a quick check of your health portal after your visit will usually reveal it. BMI has long been a main metric medical professionals use to assess health, but is it all it’s cracked up to be? New research suggests that when it comes to long-term heart disease risk, another measurement called waist-to-height ratio may be more helpful. We spoke to doctors about which is really a better gauge of your health and how you can improve your numbers if they’re not where you hoped they’d be. 

What is BMI?

“BMI is a calculation that compares your weight to your height,” explains Bernadette Anderson, MD, MPH, physician and award-winning author. “It is commonly used as a quick screening tool to help identify whether someone’s weight may be associated with increased health risks.”

And while a BMI calculator is often used as a tool for assessing health risks, it doesn’t account for everything. “It doesn’t directly measure body fat, distinguish fat from muscle or tell us where fat is stored in the body,” continues Dr. Anderson. “I think of BMI as one piece of information about your health, not a definition of your health.”

Why you should pay attention to waist-to-height ratio

“Waist-to-height ratio compares the size of your waist to your height,” says Dr. Anderson. “What makes it particularly useful is that it gives us information about central or abdominal fat. Excess abdominal fat, particularly visceral fat, the deeper fat surrounding our organs, is associated with greater risk for heart disease, high blood pressure, type 2 diabetes and other metabolic conditions.”

So why is waist-to-height ratio being compared to BMI? New research from scientists at the University of Pittsburgh School of Medicine, published in The Lancet Regional Health – Americas, found that after examining data from more than 2,700 participants for more than five years, waist-to-height ratio was better at predicting long-term heart disease risk than BMI. This was especially true for people with a BMI under 30, who are not considered obese by BMI standards but may still carry excess stomach fat linked to greater heart disease risk, something waist-to-height ratio can help identify.

“I think this research reinforces something important: We have to look beyond weight alone when we’re talking about health,” says Dr. Anderson. 

“Where we carry weight can sometimes tell us something that weight alone cannot,” adds Dr. Anderson. “I don’t see this research as a reason to simply replace BMI with another number. To me, it is a reminder that health rarely fits neatly into one measurement. Waist-to-height ratio may give us another simple way to recognize risk that we might otherwise miss.”

How to measure your waist-to-height ratio

“Measure your height and your waist using the same unit, either inches or centimeters, and divide your waist measurement by your height,” explains Dr. Anderson. “For example, if your waist is 32 inches and you’re 66 inches tall: 32 ÷ 66 = 0.48.” 

“Use a flexible tape measure” to get your waist size, recommends Meghan Garcia-Webb, MD, a triple board-certified doctor in internal medicine, lifestyle medicine and obesity medicine. “Locate the top of your hip bone. This is about the same level as your belly button. Wrap the tape measure around your abdomen at this level, breathe out naturally and record the number. That is your waist circumference.”

And while it may be tempting to suck in your stomach while measuring, Dr. Anderson cautions against this to make sure the number you get is an accurate reflection of your health.

When you calculate your waist-to-height ratio, here’s how Dr. Webb says you should think about your results.

• Normal: 0.4 to 0.49
• Increased health risk: 0.5 to 0.59
• Even higher risk: 0.6 and above

“The easiest way to remember it is: Try to keep your waist circumference less than half your height,” adds Dr. Anderson.

3 tips for improving your numbers

If your waist-to-height ratio doesn’t quite turn out where you want it to be, the good news is that lifestyle choices can improve your numbers and help reduce your risk of certain health conditions in the process, says Frank Agullo, MD, FACS, board-certified plastic surgeon and clinical associate professor of plastic surgery at Texas Tech University Health Sciences Center Paul L. Foster School of Medicine. That means you have the power to change things. 

“Visceral fat is very responsive,” says Dr. Agullo. “It’s usually the first fat to arrive when your habits slip and the first fat to leave when your habits improve. This is good news, because you can monitor your waist circumference as you’re dieting and often see more change than on the scale, which can be discouraging.” His advice: 

• Eat enough protein: Dr. Agullo recommends aiming for 25 to 35 grams of protein with each main meal. “Protein preserves muscle, and muscle is what keeps your metabolism from sliding as you age,” he says. 
• Get enough fiber: Aim for 25 to 35 grams of fiber a day, recommends Dr. Agullo. “Fiber slows how fast sugar enters your bloodstream, which blunts the insulin spikes that encourage the body to store fat centrally. It also helps keep you fuller for longer,” he adds. 
• Get enough sleep: Dr. Agullo recommends clocking seven to nine hours of sleep a night, even on the weekends. “Short sleep raises cortisol, a stress hormone that encourages abdominal fat,” he explains. 

The bottom line on BMI vs. waist-to-height ratio

The thing with health metrics, including BMI, is not that they aren’t helpful tools for some, but that they don’t account for everyone. Even if you have a healthy BMI, that doesn’t necessarily mean your heart health is where it needs to be. The key to maintaining good health—including reducing your risk of cardiovascular disease—is prioritizing the everyday choices that can help you get there.