ABDOMINAL OBESITY

Scaling Down This Deadly Risk*

by Caryl S. Avery

Diabetes, hypertension, and coronary artery disease are only a few of the many health risks that accompany abdominal obesity. Diet and exercise play a pivotal role in preventing a thickening of the waistline and in fighting existing potbellies. By helping patients get a grip on love handles early, physicians can keep the associated health problems from spilling over.

Beer belly, spare tire, love handles—the names we give to potbellies make them seem benign, if not somehow functional. But mounting evidence suggests that abdominal obesity, more than total body obesity, is a serious risk factor for diabetes, hypertriglyceridemia and low high-density lipoprotein cholesterol, hypertension, and coronary artery disease. Today, benign neglect of a paunch—even in a normal-weight patient—may represent a missed opportunity for early intervention and prevention.

“When you talk about a potbelly, what you’re talking about predominantly is an increase in intra-abdominal fat,” says Ahmed H. Kissebah, MD, PhD, professor of medicine and pharmacology and chief of the endocrine metabolic division at the Medical College of Wisconsin in Milwaukee. “Expansion of the waist is really an index of the amount of fat in the intra-abdominal cavity. There is also extra-abdominal, or subcutaneous, fat around the waist. But in terms of impact on health, intra-abdominal fat is more serious.”

As people gain weight, their bodies tend to distribute fat in one of two ways, Kissebah explains. Some normal-weight people have more intra-abdominal fat, and as they become obese, they put on weight intra-abdominally first, then extra-abdominally, and finally in the gluteofemoral region. Because this pattern is more common in men, a French researcher dubbed the pattern “android” in 1947, noting even then that people who had diabetes and heart disease were more likely to have this type of body fat distribution. In popular parlance, people who have android fat distribution are often referred to as “apples.”

In contrast, those who gain weight in the reverse order—by expanding first their gluteofemoral, then their extra-abdominal, and finally their intra-abdominal fat—are referred to as “pears.” More common in women, this type of fat distribution is called “gynoid.” And, Kissebah says, “lower-body or gluteal-femoral fat has the least impact on health—almost none.”

In fact, studies show that women can carry up to 60 lb more fat than men without significantly increasing their cardiovascular risk, provided that they carry it low—in the hips and thighs, according to Bryant Stamford, PhD, director of the Health Promotion and Wellness Center and professor of allied health in the School of Medicine at the University of Louisville, Kentucky.

Stamford cautions against over-generalizing: Men can be pears and women apples. And, he notes, women who carry their fat in the abdominal area lose their protective edge.

The Culprit Can Be Disease

Don’t assume every potbelly was born in the dessert line. Both men and women can appear upper-body obese without being obese at all. Although potbellies most commonly result from excessive fat in the stomach area, physicians need to consider other causes as well, says David Goldstein, MD, a family physician and medical director of the Fitness Institute in Toronto.

For example, physicians must rule out organomegaly—particularly in athletes about to embark on a contact or collision sport such as soccer, football, or wrestling. “If you’ve got an enlarged liver or spleen, you don’t want to be playing football or hockey because there’s a risk of rupture and injury,” Goldstein cautions, explaining that large organs are more likely to become ruptured.

Fluid in the peritoneal cavity, though rare, is a somewhat more common cause of a protuberant abdomen than organomegaly, Goldstein says. Such fluid is most frequently associated with chronic liver disease secondary to alcohol abuse. Goldstein notes excessive fluid can also be related to other medical problems, ranging from malnutrition to malignancies (of the ovary, colon, or intestines, for instance) that leak fluid into the abdomen.

More common still, Goldstein says, is excessive air in the gastrointestinal tract, either from swallowing (aerophagia) or from gas-producing bacteria. “As gas accumulates, it can cause distention throughout the intestines and therefore a protuberant abdomen,” he says.

In addition, Goldstein suggests that physicians ask female patients about their menstrual cycles because some gynecological problems, such as polycystic ovary disease, can cause enlargement of the ovaries and often accompany menstrual abnormalities, such as amenorrhea. “And you want to rule out pregnancy,” he adds. “Because women don’t always have regular periods, they many go 3 or 4 months without a period and not suspect they’re pregnant; it happens all the time.”

Is Spinal Curve a Factor?

Another culprit often associated with belly bulge is excessive lordosis of the lumbosacral spine, but whether the curvature is a cause or an effect is a matter of debate. Goldstein says sometimes lordosis contributes to potbellies: Weakness in the abdominal muscles, which normally help keep the spine erect, increases the curvature of the lower back, shifting the contents of the peritoneal cavity forward, making the abdomen bulge. “Often, just correcting a patient’s posture will decrease the size of the potbelly,” Goldstein says.

But it can also work in reverse: Potbellies can cause lordosis, says Douglas L. Ballor, PhD, an exercise physiologist and assistant professor in the department of human development studies at the University of Vermont in Burlington. The potbelly, Ballor says, increases lordosis by essentially pulling on the apex of the normal curve of the lower back. “It’s like hanging a weight from your belly button,” he says.

Weak stomach muscles are not usually the cause of a potbelly, Ballor adds, which is why sit-ups will not make a paunch disappear. (Although abdominal exercises do not eliminate potbellies, they do help prevent low back pain, which many people who have potbellies experience from the increased lordosis, he adds.)

To help discern whether the underlying problem is a medical condition or fat, Goldstein emphasizes the importance of a thorough history and physical examination.

Sizing Up the Problem

After intraperitoneal pathology has been ruled out, all signs point to excessive fat. Goldstein then suggests doing a body mass index (weight in kilograms divided by the square of the height in meters), followed by a skinfold measurement to determine the degree of body fatness, and then a waist-to-hip ratio (WHR) to assess the fat distribution.

Although skinfold measurements can also be used to ascertain fat distribution, the WHR is preferred because it can be performed more reliably in clinical practice and because it better predicts plasma triglyceride levels and blood pressure. In addition, the WHR compares favorably with the more precise but more expensive CT scans of the abdominal area. The WHR reveals not only the relative distribution of abdominal to gluteofemoral fat, but also the quantity of intra-abdominal or visceral fat.

The main problem with the WHR, which involves measuring waist and hip girth with a tape and dividing the waist measurement by the hip measurement, is that the waist of an overweight individual often is difficult to find. Kissebah says, “So we use beauty contest criteria—defining the waist as the minimum measurement between the rib cage and the pelvis.” For the hip, he suggests using the maximum girth below the pelvic rim. Kissebah advocates having the patient lie down, although others recommend having the patient stand.

Men are considered upper-body obese when the WHR is greater than .95, women when it exceeds .85, according to Kissebah, who developed the WHR in the early 1980s. (The latest dietary guidelines from the US Department of Agriculture and the US Department of Health and Human Services simply note that ratios close to or above 1.0 are associated with greater risk for several diseases.) When it comes to the WHR, Kissebah says, “total weight—how fat the person is—is irrelevant.”

The Making of a Potbelly

Why some people are upper-body obese and some lower-body obese “is the question everybody would love to know,” Kissebah says. He notes that three hypotheses are currently under investigation. He says his research focuses on neuroendocrine variance, specifically sex hormone balance. “We know that upper-body obese women have much higher levels of male hormones compared with lower-body obese women, although we’re not talking huge amounts,” Kissebah says. “The second hypothesis says the genes do it. And the third suggests that it’s environmental—a function of behavior, stress, alcohol, and fat consumptions. In my opinion, the three factors are complementary, but it’s controversial at this time.”

Judith Rodin, PhD, and colleagues have investigated the effects of dietary behavior on fat distribution, an aspect of the third hypothesis. They have found a significant association between a higher WHR and weight cycling—repeated bouts of weight loss and regain. “Our data very clearly show that people (women, in particular, because most of the studies have been done on women) who go through cycles of dieting and regaining tend to have more abdominally distributed fat,” says Rodin, professor of psychology, medicine, and psychiatry and dean of the graduate school at Yale University in New Haven, Connecticut.

One explanation may be that weight cycling results in a lowered metabolic rate. Research indicates that “yo-yo” dieters lose weight more slowly on their second try on a calorie-restricted diet than on their first, and suggests that wrestlers who go through weight cycles to “make weight” for their matches have lower resting metabolic rates than their noncycling teammates.

Another reason may be that yo-yo dieting increases fat consumption. Animal research by Judith S. Stern, ScD, and colleagues at the University of California, Davis, shows that when rats are allowed to self-select from protein, fat, and carbohydrate, they choose a diet that’s about 35% fat—just as humans do. “But when the rats are forced to lose weight and then allowed to regain, they select a high-fat diet—with 50%, even 60%, of calories from fat,” says Stern, professor of nutrition and internal medicine.

Similarly, Rodin notes, research shows that women who had a history of relapse after dieting consumed more fatty snacks. And high-fat diets have been shown to be associated with increased abdominal fat.

In addition to yo-yo dieting, weight gain and loss from repeated pregnancies also correlates with more abdominally distributed fat. The cause remains unclear. One hypothesis is that women who either don’t breast-feed or don’t breast-feed long enough are more likely to gain weight abdominally because lactation puts a great demand on fat stores.

Rodin notes that some experts argue that a high WHR following repeated pregnancies is not due to increased fat, but to sagging skin. Yet Rodin’s research in progress using MRI or CT scans suggests that visceral fat is part of the cause and not just subcutaneous fat. “In animal studies, weight cycling has already been shown to selectively increase intra-abdominal fat,” Rodin says. “We like to think the same is true of humans but can’t be sure until the MRI or CT scans data are in.”

Tightening the Belt

Primary care physicians are especially well suited to helping “apples” prevent the health complications that accompany upper-body obesity. Step one is getting a grip on love handles early. Making a WHR a routine part of physical examinations is an important preventive measure.

In addition, physicians can educate patients who have let out their belts a few too many notches about the potential health consequences. And patients who have a WHR exceeding .85 can be encouraged to reduce their caloric intake and increase physical activity—even if they’re not obese overall.

“The important thing is to combine diet and activity,” Kissebah says. The good news, he adds, is that abdominal fat, because of its hyperactivity, responds well to weight reduction—so even a modest weight loss may help.

Because dietary fat tends to land in the abdomen (at least in animals), a low-fat diet is generally recommended, according to Stern and Stamford. However, Kaplan discusses one study that found that a low-fat, high-carbohydrate diet accentuated both the hyperglycemia and hyperinsulinemia in eight nonobese patients who had hypertension. Consequently, for such patients, calorie reduction may be better achieved by eating unsaturated fats rather than large amounts of carbohydrates.

Rodin agrees that dieting is important for patients who have a paunch because a high WHR appears to be an independent risk factor, even controlling for obesity. So an overweight person who has a potbelly walks into the physician’s office with two risk factors.

However, Rodin advises caution when recommending a diet for someone who has a history of weight cycling. “If they lose and regain, you might be adding a third risk factor—cycling,” she says. “I’m not recommending that patients don’t diet—especially those with two risk factors already. But I think physicians need to be sensitive to their patients’ dieting history.”

For most people, keeping weight off is more difficult than taking it off. Physicians can tell patients that exercise can ease this task. Kissebah says, “Weight-loss programs show that individuals who maintained a high degree of physical activity are the ones who maintained the weight loss.” Plus, Stern notes that weight-cycling rats don’t select a high-fat diet when they exercise: “Exercise appears to prevent this high-fat selection.”

Barring underlying pathology, patients can shrink the size of their paunches through proper diet and exercise. But success may depend on early intervention and prevention. By describing the health risks of potbellies and providing a treatment plan, physicians can help patients win the battle against belly bulge.

*Originally published in The Physician and Sportsmedicine,

vol. 19, no. 10, October 1991.