Is it possible to be both obese and healthy? Obesity has long been associated with cardiovascular disease, Type 2 diabetes and several forms of cancer, but a lingering question is the degree to which obesity itself contributes to poor health. For every study suggesting that as body mass index, or BMI, increases, the risk of chronic disease and early death also increases, there are others demonstrating that people can be healthy — or unhealthy — at almost any weight.
For example, a study published in July in the Lancet examined data from more than 10 million people from four continents and found that BMI outside the normal range — underweight and overweight — was associated with an increased risk of poor health and early death. However, a similar study of more than 300,000 Korean adults, also published in July, concluded that something called "metabolic health" was more important than BMI when it comes to estimating future health risk.
Metabolic health, a term that is coming into more general use, means not only that you don't have cardiovascular disease or Type 2 diabetes but also that you don't have the precursors of these diseases: increased levels of blood sugar, blood pressure or cholesterol.
Although it's possible that genetics play a role in staving off these conditions at higher weights, how we live matters, too. Metabolically healthy obesity is more common among younger women who eat a healthy diet, are physically active and have a higher socioeconomic status. That's probably because women are more likely to seek out preventive health care, and lower socioeconomic status affects the availability of resources that support a healthy lifestyle.
What's clear is that health is something that's ours to be lost or gained based on the sum of our actions. A healthful diet, regular physical activity and avoiding tobacco use are important for protecting health and preventing disease.
But research shows that the majority of Americans are not hitting those marks.
If you want to get healthy, be healthy and stay healthy, then focusing on health-promoting behaviors is far more important than worrying about BMI. One reason is that BMI isn't the best way of looking at weight. BMI can't tell the difference between body fat and lean muscle — or where body fat is distributed. Maintaining lean muscle supports health, especially as we age. Excess body fat can increase the risk of chronic disease, but that largely depends on where that fat is located. Subcutaneous fat (fat under the skin) is thought to carry the least risk, while visceral fat (fat around the body's abdominal organs) carries more risk, and fat deposits in the liver and muscles carry the most risk.
As for whether weight loss improves health, that depends. For healthy obese individuals who have normal blood pressure, blood sugar and cholesterol levels, losing weight has not been shown to improve those metrics any further, and in some cases it contributes to unhealthy physical and psychological effects.
One unfortunate finding of long-term research studies is that as many as half to two-thirds of healthy obese individuals eventually become unhealthy. While it's unclear why this happens, increasing age and decreasing physical activity are likely factors.
Two other factors may be weight stigma and socioeconomic status, because they can be profound sources of stress. Stress contributes to the health problems that increase risk of cardiovascular disease and diabetes.
Regular physical activity is vital for good health for people regardless of weight, but it also may also explain why obesity isn't always associated with metabolic health risks. Physical activity promotes stable blood sugar, blood pressure and cholesterol levels and helps maintain or build lean muscle. Research studies that actually consider fitness when looking at the connection between weight and health tend to find that healthy obese individuals are fitter than their unhealthy obese peers and have essentially the same risk of chronic disease and premature death as healthy normal-weight participants.
Physical activity doesn't have to come from just gym workouts or other planned activity, either. Anything that gets you out of your chair makes a difference.
It's important to remember that individuals are not statistics. Weight has become a handy-but-inaccurate shorthand for health. Having a BMI in the normal range doesn't protect you from developing health problems, and having a BMI in the overweight or obese range doesn't guarantee that you are unhealthy or will become so. What's important is your individual health and the actions you take to improve or maintain it.
Carrie Dennett is a Seattle-based registered dietitian nutritionist and owner of Nutrition by Carrie.