Obesity has more than doubled since 1980 worldwide. The number of deep-vein clots is rising right along with that.
Doctors aren't yet sure exactly why, but people who have a body mass index of at least 30 are more likely than people of normal weight to get a blood clot deep in a vein, called deep vein thrombosis, or DVT.
The greatest danger from deep vein thrombosis (DVT) is that the clot will break loose, travel through your blood, and damage an organ.
"The place it gets stuck most commonly is the lungs, and that's called a pulmonary embolism (PE)," says Molly Cooke, MD, of the University of California, San Francisco. Less often, another clot can form and travel to the brain and cause a stroke. If a clot travels to the heart, it could cause a heart attack. A clot in the kidneys can cause kidney failure.
People who are obese tend to have a less active lifestyle. Being idle makes your blood flow sluggish, and this makes clots more likely.
Extra fat around your belly will also stop blood from moving easily through the deep veins.
Obesity changes the chemical makeup of blood, and it leads to inflammation. Both make your blood more prone to clotting.
And obesity puts you at risk for diabetes, which boosts your chances for getting DVT, too.
What You Can Do
Studies show that losing weight can change your blood chemistry and lower your risks. Overweight and obese adults who did moderately intense aerobic exercise improved their blood health, even if they didn't lose weight.
Unfortunately, it doesn't look like you can lower the risk of a second DVT by losing weight after you've had one.
A lot of fish with omega-3 fatty acids in your diet may help protect your blood against abnormal clotting. Avoid high-carb diets -- they can make your blood more likely to clot.
Your doctor can and should help you get from obese to a healthy weight.