You already have plenty of reasons to keep your waistline trim. Now here’s one more: A new study published in the journal Oral Diseases found that overweight people had worse oral health than their normal-weight peers, with obese people having a nearly six-fold higher risk of severe gum disease.
The research involved 160 adults in Thailand, 70% of whom were overweight or obese. Overall, people with body mass indexes (BMIs) of 23 or higher—which is considered overweight for the Thai population—had more dental disease and more severe periodontitis (a serious gum infection) than those with lower BMIs. Levels of white blood cells and C-reactive protein, a marker of inflammation in the blood, were also higher in overweight participants.
RELATED: Best and Worst Foods for Your Teeth
A BMI of 25 or higher, which is considered obese in Thailand, was even more strongly associated with poor oral health. Overweight participants were 4.2 times more likely to have severe gum disease than normal-weight people; obese people were 5.9 times more likely.
Obesity is often associated with unhealthy habits, so it might be assumed that some obese people don’t take care of their bodies, or their mouths, as well as thinner people do. To account for this, the researchers adjusted their results to control for factors such as blood sugar levels, smoking, and exercise habits, along with age and gender. The associations weakened some—to 3.6 and 4.5 times more likely—but remained significant.
The study results aren’t surprising, says Yiping Han, PhD, professor of microbial sciences in dental medicine at Columbia University, because it is well known that obesity contributes to inflammation in the body, which has long been associated with gum disease.
“We know inflammation is an underlying cause of many diseases—periodontal disease but also cardiovascular disease and many cancers,” says Han, who was not involved in the new study. “Obesity is a risk factor for many of these ailments, so there’s a natural connection there.”
Salvador Nares, DDS, director of periodontics research at the University of Illinois at Chicago College of Dentistry, says that obesity-related inflammation has been shown to deregulate the body’s immune system.
“Periodontal disease is an infectious, immune-mediated disease,” says Nares, who was also not involved in the new research. “That means that obese people are going to be more susceptible to the bacteria that causes gum disease, and the bacteria that cause cavities, than other folks.” This trend has also been seen in the United States, he says, even in young children.
The study could not show a cause-and-effect relationship between obesity and gum disease, and in fact, Han says, “we don’t actually know if this is a one-way or two-way street.” For conditions like diabetes, she explains, the relationship is bilateral: “Periodontal disease will affect diabetes and diabetes will worsen periodontal disease, so that could be a possibility here, too.”
Still, she says, the study should sound the alarm about yet another potential drawback of packing on extra pounds. “People should be watching their weight regardless, because obesity is a risk factor for so many ailments,” she says. "This is another possible one to add."
To get our best wellness advice delivered to you inbox, sign up for the Healthy Living newsletter
Periodontal disease has also been linked to many health conditions, she says—like an increased risk of stroke and heart disease—so it’s important to maintain good oral hygiene as well as a healthy weight. (In fact, the study authors write that the interplay between obesity and gum disease “may enhance the risk of cardiovascular disease in overweight or obese individuals.”)
Periodontal disease can also lead to tooth loss, and may even be linked to rheumatoid arthritis and premature death. So avoiding risk factors such as smoking, poor nutrition, diabetes, and, yes, obesity is always a good idea. “The take-home message here is that the body is connected,” says Nares, “and the mouth, in many ways, is a window to a person’s systemic health.”