Written byPatrick Sullivan. Medically reviewed in February 2024 byJoanne Perron, MD.
Updated February 16, 2024.
Your body mass index (BMI) may have been measured during your last health examination. It is a crude tool that healthcare providers use to estimate the amount of fat in your body, determining the ratio of your height to your weight.
Although BMI is often used to indicate whether someone is overweight or underweight, it is not the only measure used for this purpose – and it is not a perfect measure of overall health. There's another figure that's arguably more useful: the waist-to-height ratio (WHR). A fairly simple measurement that involves your waistline, WHR has been endorsed by more and more healthcare providers in recent years.
That is the message of research that has been going on for decades and has been strengthened in recent years.
A brief history of waist size
In the 1950s, health researchers began to determine the way fat was distributed throughout the body, paying attention to whether it was located in the upper or lower body. In the 1980s and 1990s, scientists noticed that WHR helped predict the risk of death and heart disease. Studies since then have continued to emphasize the usefulness of the WHR measurement.
The higher your WHR, the larger your waist in relation to your height and the more weight you carry around your midsection.
- A healthy WHR is generally around 0.4 to 0.49.
- A ratio of 0.5 to 0.59 indicates an increased risk of health problems.
- A ratio higher than 0.6 indicates obesity and an even greater risk of health problems.
Over the years, many health experts have used fruit metaphors to help people visualize WHR. In general, people with a rounder, apple-shaped body tend to have more fat around the abdomen and therefore a larger waist and a higher WHR. People with a pear-shaped body have a relatively thinner waist (and a lower WHR) and more fat is located lower in the body, around the hips, buttocks and thighs.
Reasons to be wary of BMI
WHR is an effective way to measure a person's body composition and overall health, but BMI has been used for some time and is still a popular measurement.
To determine your BMI, divide your weight in pounds by your height squared and multiply by 703. (You can also use aonline BMI calculator for adultsprovided by the Centers for Disease Control and Prevention.)
Your final BMI calculation places you in one of five groups:
- A BMI lower than 18.5 means you are underweight
- Between 18.5 and 24.9 is considered a healthy weight
- Between 25 and 29.9 is considered overweight
- Between 30 and 39.9 is considered obese
- 40 years and older are considered extremely obese
The problem is,BMI is not a perfect indicator of health. Firstly, muscle mass is not taken into account. This means that a person who is physically fit and moderately muscular may be considered "overweight" or "fat" because muscle tends to weigh more than body fat.
BMI also cannot measure the amount of fat around the abdomen. A lot of belly fat indicates a larger waistline and can be especially dangerous for your heart (more on this below).
It is also important to note that BMI is not a good predictor of health risks between racial groups. This means that two people from different racial backgrounds may have different risks at similar BMI levels.
For example, Asians and Asian Americans may face greater health risks at a lower BMI than non-Asians. Research has shown that the risk of developing diabetes increases with lower BMI values in South Asians and Chinese compared to blacks and whites. Healthcare professionals should consider this information when deciding what a particular patient's BMI may mean for them.
Why waist sizes matter
While BMI remains the most important measure of body health, research suggests that paying attention to waist size may be more accurate. WHR research specifically points to why pear-shaped people tend to live longer than apple-shaped people, even though their overall weight and height are similar.
A 2019 review published inCanadian general practitionerlooked at the issue of "central obesity" (or large fat deposits around the waist) in people whose BMI was considered to be in the healthy range. Researchers found that central obesity (commonly described as an apple shape) was more closely associated with a risk of disease and death than simple weight or BMI measurements.
Another study, published in 2019 inEuropean Heart Journal, looked at postmenopausal women in the United States with BMI measurements considered healthy. Researchers found that those who had more upper body or "trumpet" and less leg fat were three times more likely to develop heart disease than those who had no upper or lower body fat, or those with only leg fat. A major overview of research published in 2020 inBMJmeanwhile, found that central obesity was significantly associated with a higher risk of premature death.
Meanwhile, a consensus statement was published in 2020 iNature Reviews Endocrinologyrecommended that HPCs consider waist circumference as an essential vital sign. The authors recommended measuring and taking this into account, just like weight and blood pressure.
What's the problem with belly fat?
Scientists don't know exactly what that doescertain types of fat are dangerous, but it probably has to do with where – and how deep – it is in your body.
If you are considered pear-shaped, your fat tends to be located mainly in your lower half. It's also usually mainly subcutaneous fat, meaning it's just underneath the skin.
People who are apple-shaped, on the other hand, have more fat in the abdomen. The fat, called visceral fat, is deeper and collects around the organs. Researchers believe that visceral fat can affect the body's systems in a more dangerous way than subcutaneous fat. For example, visceral fat can disrupt hormones and produce chemicals that lead to diabetesinflammation, a major cause of heart disease and cancer.
What you can do
First, it's important to understand that targeted fat loss, also called "spot reduction," doesn't work. There is no way to specifically lose belly fat by training the muscles around the abdomen. So while sit-ups and crunches can help you develop some of your abdominal and core muscles, they won't burn belly fat on their own.
Instead, the best way to lose fat across the board is to maintain a healthy lifestyle. This includes:
Exercise:To burn calories, do at least 30 minutes a day of aerobic exercise, which will get your blood flowing and your heart rate up. Consider brisk walking, jogging, cycling, hiking, sports or strength training with weights or elastic bands.
Cost:Eat a healthy diet with an emphasis on fruits and vegetables, whole grains, lean proteins and healthy fats from sources such as vegetables and seafood. As much as possible, reduce your intake of processed foods and foods with added sugars, such as sugary soda, candy, and cookies. Drink alcohol in moderation, or not at all. This means no more than two drinks per day for men and one drink per day for women. Some research suggests a link between alcohol consumption and obesity.
Sleep:Not getting enough good quality sleep can increase your risk of gaining more visceral fat. Aim for seven to nine hours of sleep per day. night. Some research suggests that havingsleep apneaincreases the chance that an overweight person will gain more weight. (Sleep apnea is a condition in which you wake up repeatedly during sleep.)
Stress reduction:When you're stressed, your body produces more of the hormone cortisol, which can increase visceral fat storage. There are many ways to reduce stress, from exercise to...practice meditation, to use deep breathing methods, to keep a diary or to talk to friends or someonetherapist.
The good news is that when you combine these healthy habits (with an emphasis on exercise), visceral fat is reduced more easily than subcutaneous fat. Maintaining a healthy lifestyle for just a few months can improve your body weight and size – and deliver results that can last a lifetime.
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Center for Disease Control and Prevention. About BMI for adults. Since last review on June 3, 2022.
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