Alison Judge isn't a fashionista. Nor is she obese. But she admits that she is getting a little tired of wearing sweats, the only type of pants that doesn't show off what she affectionately calls her "middle-age muffin" and what the rest of us call the jelly belly. "Things just started moving south after 40," says Judge, 47, a marketing consultant from Croton-on-Hudson, N.Y. "Any extra weight goes right to my gut. I know it's not healthy, but it's tough to fight Mother Nature."
Indeed it is. But here's another reason to wage that battle. A growing body of evidence is implicating obesity as a major risk factor for a seemingly endless roster of diseases: certain cancers, high blood pressure, high cholesterol, stroke, diabetes and gallbladder problems—even Alzheimer's disease.
When it comes to obesity and the brain, where you carry your weight may be a bigger risk factor for cognitive decline than how many extra pounds you're packing. And that's frightening news for people in middle age, a time when six-pack abs quickly morph into abdominal flab.
A new study published online today in the journal Neurology shows that belly fat in middle age—even among folks who are at a normal weight, like Judge—may put you at increased risk for dementia. It's a finding that even astounded the researchers. "We know that obesity is somehow linked to Alzheimer's," says study author Rachel Whitmer, a research scientist at the Kaiser Permanente Division of Research in Oakland, Calif. "But no one was more surprised than me at just how big an effect belly fat seems to have."
The observational study followed some 6,500 people, ages 40 to 45, for more than three decades, starting in the mid-1970s. All participants were given a sagittal abdominal diameter (SAD) measurement, a simple procedure in which a technician uses calipers to measure the distance from the back to the upper abdomen, midway between the upper pelvis and bottom of the ribs. At the end of the study about 1,000 participants, or 16 percent, were diagnosed with dementia. After factoring out known dementia risk factors such as diabetes, stroke, hypertension and high cholesterol, data analysis showed that potbellies were a bigger risk for cognitive impairment than obesity alone.
And the fatter the gut, the higher the risk. Researchers used standard body mass index (BMI) measurements (weight divided by height in meters squared) to classify folks as normal weight, overweight or obese. Participants who were overweight and had a bulging gut were 2.3 times as likely to develop dementia as people with normal weight and belly size. Obese participants with large guts were 3.6 times as likely to develop dementia.
And if you are at a normal weight but have a gut, you aren't off the hook. The study showed that participants with BMIs of 25 and below who sported a gut were 89 percent more likely to develop dementia than hefty persons without a belly bulge.
That stubborn spare tire is the bane of the middle-aged, especially women. Hormone loss seems to play a role in its development after 40. "It's called the meno-pot," says registered dietitian Kathleen Zelman, director of nutrition for WebMD. "As women lose estrogen, weight gathers in the midsection." Genetics also plays a role in determining whether you are apple-shaped, with a big midsection, or pear-shaped, with a small waist but big buttocks and thighs. And let's not forget stress. A hormone called cortisol, released during the stress response, has also been implicated in developing belly fat.
Researchers aren't quite sure exactly how belly bulge plays a role in dementia, since obesity, with or without a gut, seems to affect Alzheimer's development. Beta-amyloid is a naturally occurring protein that goes awry in the brains of Alzheimer's patients, changing shape and forming plaque that disrupts normal nerve cell processes. Research shows that a high BMI is associated with higher levels of beta-amyloid, says Dr. Sam Gandy, Chair of the Alzheimer's Association Medical and Scientific Advisory Council. (According to the Alzheimer's Association, one in six women and one in 10 men who live to be at least 55 will develop Alzheimer's disease.)
But belly fat is clearly a factor, and scientists have some ideas why. The technical term for the potbelly is visceral fat. Unlike subcutaneous fat, the stuff you can pinch, visceral fat is tucked deeper within the abdomen, surrounding vital organs such as the heart and liver. It is considered particularly dangerous since it is active, producing chemicals that can affect health. Scientists suspect that it plays a role in inflammation, which is linked to insulin resistance, certain cancers and especially cardiovascular problems.
"There are still a lot of unanswered questions about obesity and Alzheimer's," says Gandy. "But unlike family history and age, which are important predictors for Alzheimer's, you can do something about your weight. It's a risk factor that is modifiable."
And there is some good news on that front—so to speak. Visceral fat is especially amenable to diet and exercise. "It's not a stubborn fat," says Dr. Keith Bachman, a weight management expert with Kaiser Permanente's Care Management Institute in Portland, Ore., adding that even a modest weight loss of 5 to 10 percent can reduce obesity-related risks.
One of the best ways to lose the paunch may be to incorporate more whole grains into your diet. Recent research from Pennsylvania State University, published in the American Journal of Clinical Nutrition, showed that folks who added whole-grain breads and cereals to a weight-loss regimen lost more belly fat than those who chomped on refined grains, like white breads. The whole-grain group also showed a nearly 40 percent drop in C-reactive protein, an inflammatory marker implicated in heart disease. Of course, exercise is another major factor—physical inactivity is closely associated with the belly bulge.
Determining the size of your belly is a little more complicated than looking at the roll of fat above your pants. Some researchers believe the best method is the SAD measurement (was there ever a more apt acronym?), but since it isn't part of a normal workup, most of us will be stuck measuring our BMIs and waists. Research shows that women whose waists are larger than 35 inches and men whose waists are larger than 40 inches are at greater risk for disease. But even waist sizes a few inches less than that can increase your risk, though to a lesser extent.
The big question remains whether slimming down actually reduces Alzheimer's risk. Doctors admit that a clinical trial of that sort may be difficult and unethical, since one group of patients would have to remain obese, a known health risk. But that's no excuse to carry around a spare tire, says Whitmer. "About half the adults in this country have abdominal obesity," she says. "The scale doesn't tell the whole story. People have to be aware of where they carry their weight and then do something about it." To protect your brain, that something may be as simple as dropping a few pounds.