Miriam Bredella, MD
Miriam Bredella, MD, associate professor of radiology at Harvard Medical School and a musculoskeletal radiologist at Massachusetts General Hospital, both in Boston.
If you’re overweight, then you already know that you’re at higher risk for lots of serious health problems.
Perhaps despite these increased risks, you either don’t want to or aren’t able to shed extra weight.
If you’re not going to drop pounds, that’s certainly your choice—but at the very least…if you have any regard for your own health…there are certain exercises that new research shows you need to do.
Doctors once believed that only very old people and very thin people needed to worry about brittle bones, but new research has turned that idea on its head. A mounting body of evidence suggests that obesity is a major risk factor for osteoporosis and fracture risk—no matter your age.
But it’s not just any fat that’s problematic. The kind of fat that you need to worry about is hard to see. It settles around the internal organs within the belly. It’s called visceral fat, and it can wreak havoc on your body.
For a recent study, researchers analyzed young men (average age 34) who had an average body mass index (BMI) of 36.5, which put them well into the “obese” category. The men underwent a sophisticated CT scan to determine their bodies’ amounts of abdominal subcutaneous fat (fat that lies directly under the skin)…abdominal visceral fat (deeper inside)…and total abdominal fat (both of those types), as well as thigh subcutaneous fat and thigh muscle. The men underwent a different and very high-resolution CT to determine the strength of their wrist bones.
Researchers found that among men with the same BMIs, those who had more visceral fat had weaker bones compared with those who had more subcutaneous fat. But no associations were found with the other types of fat. There was a positive correlation seen with thigh muscle—the more muscle mass, the stronger the bones, among men with the same BMIs. In a prior study, these same researchers had found similar results among young women, so all of these findings apply to both genders.
Researchers are still unraveling the links between fat and bone weakness. For example, “It’s known that people with more visceral fat have less growth hormone in their bodies,” said Miriam Bredella, MD, the study’s lead author. Growth hormone reduces fat, which leads to fatty acids being released into the blood. But an obese person always has a higher-than-normal amount of these fatty acids in the blood—so the already high levels of fatty acids may trick the brain into believing that the body already is producing sufficient levels of growth hormone even when that is not the case. Growth hormone also plays a role in strengthening bones. In addition, visceral fat cells secrete adipokines, inflammatory molecules that stimulate the cells that break down bone (osteoclasts).
You’re probably wondering whether your body is harboring the kind of fat that’s bad for your bones. Unfortunately, the only foolproof ways to find out—getting a CT scan or an MRI—are expensive, and a CT scan exposes you to harmful radiation. But there is a simple way to get a ballpark idea of what’s going on deep beneath the surface of your skin.
“If your BMI is in a ‘normal’ and healthy range, then you likely don’t have much visceral fat,” said Dr. Bredella. But if you’re overweight or obese, measure your waist to see whether you’re in the danger zone, she said. For example, she said, men whose waist size exceeds 40 inches and women whose waist size exceeds 35 inches are likely to have dangerous levels of visceral fat.
The only way to reduce your level of visceral fat is to lose weight altogether, said Dr. Bredella. But what if you don’t want to lose weight…or if you can’t, no matter how hard you try?
In that case, it’s important to do what are called “weight-bearing” exercises—ones in which (unlike cycling or swimming) you fully support your own weight during the activity. Weight-bearing exercises will strengthen your bones and help counteract the negative effects of visceral fat, Dr. Bredella said.
Doing even as little as 10 minutes per day of any of the following weight-bearing activities will help give your bones the protection they need…