American College of Physicians: Internal Medicine — Doctors for Adults ®


Nature and nurture: twin culprits in obesity epidemic

From the June ACP Observer, copyright 2004 by the American College of Physicians.

By Janet Colwell

NEW ORLEANS—While obesity has become a major public health problem, the medical community is in a quandary over why some people gain weight—and whether doctors can do anything to help the most severely obese patients.

"Seventy-five percent of mature adults are overweight or obese," said Frank Svec, MD, PhD, professor of medicine at Louisiana State University Health Sciences Center in New Orleans. "What happened to the other 25%? What keeps those people from becoming obese?"

Some audience members attending Dr. Svec's Annual Session program, "Managing the Medically Complicated Obese Patient: What Works and What Doesn't," credited genetics. Others said behavior—caloric intake or exercise—is more important.

In fact, said Dr. Svec, an endocrinologist whose research focuses on the etiology of obesity, there's evidence on both sides.

Ongoing debate

On the genetic side of the debate, studies of adopted children have shown that weight gain tends to correlate with the biologic, not the adoptive, parents. And studies examining twins show that they tend to mirror each other in weight gain.

At the same time, evidence on the influence of environment is equally compelling. "Supersized" meals and sedentary lifestyles correlate with rising obesity levels.

Given that you can't do anything about genetic predispositions, one of the most effective strategies is to encourage patients to limit portion size and monitor their intake. "The way you eat influences how much you eat," said Dr. Svec. "The person who serves you food influences how much you eat."

While Dr. Svec didn't profess to have a definitive answer, he leaned toward viewing social problems as the root cause of rising obesity. Children are exercising less and engaging in more passive activities, he said. And overweight parents tend to perpetuate the problem by passing on bad eating habits and tolerating weight gain in their children.

Few success stories

Despite an abundance of low-carb diets, fat-burning drugs and surgical solutions that have emerged in recent years, physicians attending the lecture had few success stories. Gastric bypass surgery works with some severely obese patients, some audience members said, but no one reported any success with drugs.

Some said patients had limited success with weight loss plans, such as the Weight Watchers program, or by using tactics such as keeping a journal and logging what they eat each day.

However, doctors in the audience expressed frustration over difficult cases. One physician said a 350-pound patient was not successful in changing his eating habits, even after undergoing quadruple bypass surgery. Another noted that gastric bypass surgery often works initially but that there are significant post-surgery issues, including depression, because patients cannot eat normally. Dr. Svec noted that surgery should be reserved for those who have massive obesity and complications.

Drugs, while moderately effective, are not the panacea that the medical community hoped for.

"There are not many success stories [with drugs] because the goals that both doctors and patients want are not frequently within the range of the pharmaceutical agents," Dr. Svec said. While the agents have a positive effect on metabolism by reducing obesity, "the 'human' nature of patients and doctors wants even greater effects."

Prescription drugs currently on the market fall into two categories: appetite suppressants and fat absorbers. The two that have been approved for long-term weight loss are sibutramine, a tertiary amine that suppresses appetite by acting on the central nervous system, and orlistat, which prevents fat absorption by stopping the digestion of dietary triglycerides, resulting in up to 300 lost calories a day.

Some patients respond well to these drugs, Dr. Svec noted, but they are not a cure-all. Drugs must be used in conjunction with aggressive diet, exercise and behavior modification programs.

He agreed with attendees that getting patients to reduce their caloric intake is key. While exercise is beneficial in the long run, it can have relatively little impact on weight loss.

Another crucial factor? Start to counsel patients early, before they become severely obese, he said. Weight control is a lifelong issue that must be monitored closely by all adults.

"My feeling is that too many people wait until they are clearly obese before they do something about it," said Dr. Svec. "People should fight each pound of adult weight gain. They should be aware of their weight so that they never have to fight a 20-pound or 40-pound weight excess. Prevention is something we need to emphasize."

Social acceptance?

One theory that Dr. Svec espoused is that society condones obesity, making it more socially acceptable to be overweight. "We no longer accept smoking," he noted, "but we tolerate obesity."

A related problem? The medical community has not settled on a basic definition of or approach to obesity. "Should we treat it as a disease?" he said. "Should we be tough on it or accept it? And is obesity a medical problem or a social problem?"

Given those types of broad, fundamental questions, "This is a bigger problem than individual physicians can take care of," Dr. Svec concluded. "Society has to change."


What can internists do to help patients?

  • Start with diet and exercise. Some patients will respond to diet and exercise advice and start to change their lifestyle.

  • Be honest. Tell patients their body mass index (BMI) and where they fall in that spectrum. With a BMI of 25 or more, a patient is considered overweight; 30 or more is considered obese.

  • Identify the risks. Tell patients that weight gain is associated with an increase in mortality and morbidity, as well as other problems such as high blood pressure and diabetes.

  • Start early. Start working with potentially obese patients when their BMI is between 25 and 30. Don't wait until they reach 35 or higher.

  • Don't ignore the small things. Keeping a journal of food eaten, monitoring portion size and staying abreast of weight gain can be effective strategies.


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