So why is it that some of us tend to gain weight in our midsections? There is no single answer. Instead, the calculus behind the appearance of a potbelly involves four factors: genetics, eating habits, stress and hormones.
Genetics. The first part of the equation is the genetics of body shape. Some of us, says Savard, are just destined to be “apples,” with an inclination to gain weight in the stomach and upper-body region, while others are fated to be “pears,” who gain weight in their hips, buttocks, thighs and lower legs. According to Savard, it all comes down to your waist-to-hip ratio (WHR), which is the division of your waist measurement by your hip measurement. (For an accurate WHR measurement, relax your abdomen and measure at the navel and around the bony part of the hips.)
If you’re a woman whose WHR is 0.80 or lower, you are pear shaped; if your WHR is higher than 0.80, you’re apple shaped. For men (who, for the most part, are apple shaped, since they are more inclined to store visceral fat), the cutoff is 0.90 instead of 0.80.
Many experts now agree that WHR is a better indicator than body mass index (BMI) when it comes to determining someone’s disease risk. Even apples who are currently slender and have a low BMI, Savard says, could be at increased risk for disease later in life.
“If you’re a string bean with no obvious potbelly, but your waist-to-hip ratio is more than 0.80, you will tend to have more health problems than pear-shaped people if you gain weight,” she says. When WHR is greater than 1.0 in men or 0.90 in women, health experts may diagnose the condition as “central obesity.”
Eating habits. Abdominal fat, like all fat, is produced when we ingest more caloric energy than our bodies can use. And our bodies were simply never designed to withstand such easy access to the kinds of calorie-dense foods available to us today.
“It’s certainly no secret that the way we eat is out of sync with our body’s needs,” writes Floyd H. Chilton, PhD, in Inflammation Nation: The First Clinically Proven Eating Plan to End Our Nation’s Secret Epidemic (Fireside, 2005). “Most of the evolutionary forces that shaped our genetic development were exerted over ten thousand years ago when we were hunter-gatherers. Nothing in that programming could have prepared us for the Big Mac. Our bodies, and more specifically our genetics, simply aren’t designed to eat the ‘foods of affluence’ available to a twentieth-century urban dweller.”
Visceral fat was simply never a problem years ago, says Savard. Take the Pima Indians of Arizona, she says, who have prototypically apple-shaped bodies. Because the Pima Indians evolved during alternating periods of feast and famine, they developed what researchers call a “thrifty gene,” which allowed them to store visceral fat during plentiful times and use it during lean times.
Living and eating as they did traditionally, subsisting on foods they hunted, gathered or raised themselves, the Pima tended to be slender. Today, however, most are extremely overweight and suffer a 50 percent rate of diabetes among adults (95 percent of those people are overweight). “Now, with an unlimited supply of food and a more sedentary lifestyle,” says Savard, “the problem of visceral fat is not going away.”
Food today is not just more accessible, it has been reincarnated in so many heavily processed forms that we are often eating things that our bodies do not recognize as food. Our metabolism is still hardwired to process the hunter-gatherer diet of yore, and when it encounters sugary sodas and snacks that were created in a laboratory and not in a field, it is not able to process or use them efficiently. Instead, our bodies are forced to sock away that stored energy in places like our midsections where it does more harm than good.
Potbellies, also known as “beer bellies,” are often associated with drinking. But “beer does not promote weight or waist gain any more than any other source of calories,” says Meir Stampfer, MD, professor of nutrition and epidemiology at the Harvard School of Public Health. In fact, a 2003 study of 2,000 men and women from the Czech Republic, where people consume more beer per person than in any other country in the world, found no link between the amount of beer a person drinks and the size of his or her stomach. That said, alcoholic beverages are an often-overlooked, carb-dense source of calories in many people’s diets. Alcohol is processed much like a sugar in the body, and because it puts an additional strain on the liver, it may undermine the body’s fat-processing abilities.