You might see an average physique when you look in the mirror and clock in at a weight that's just a bit above normal, but that's no indicator of good health, new research suggests. A recent study found that body mass index and waistline circumference are not always the best indicators — and in fact could be dangerously inaccurate. Over the span of 20 years, the study found that over 50 percent of men and women classified as 'healthy obese' — meaning they had a BMI of 30 kg/m2 but no cluster of metabolic risk factors like high blood pressure or sugar — eventually developed the same risky conditions as the dangerously obese.
"The biggest myth about healthy obesity is that it lasts," says Bell. "Healthy obese adults have a risk for developing diabetes and cardiovascular disease. And as we now see from our own study, the state of healthy obesity is often just a phase on the way to unhealthy obesity — the highest risk group." Bell and his colleagues at University College London tracked about 2,500 middle-aged men and women and found the percentage of people falling from the healthy to the non-healthy group (and accumulating more metabolic risk factors) grew as time went on.
Dr. Robert Ross, a clinical exercise scientist, says when it comes to assuring long-term health, it comes down to whether or not you exercise and eat a balanced diet. Everyone — regardless of weight — should focus on their lifestyle and overall morbidity risk rather than the misleading classification of healthy obese versus obese. "I put far more value on the behaviors than the outcome," says Ross. "Obesity, elevated waist circumference, and elevated BMI — these are not behaviors, they are outcomes of physical inactivity and poor diet. You might have an elevated BMI and waistline, but if you're physically active, your risk for all-cause morbidity is less." He advises people with elevated BMI and waist circumference to be physically active and sustain it. "If you're doing that, you're doing the best strategy on planet earth to lead a quantitative and qualitatively healthy life," he says.
And Bell says your doctor is still your best bet for telling you if you've got an unhealthy weight, since they'll look at a variety of factors and give an accurate picture of your internal profile. "We know the limitations of BMI," he says. "But your BMI and waist circumference, together with your diet quality and physical activity levels, are useful indicators of whether metabolic risk factors are likely present, and these should be monitored." It's up to you to take immediate action for yourself, he adds, by avoiding processed foods and embedding physical activity in your daily life to reduce harmful visceral fat, build muscle, and reduce inflammation. In other words, get moving.