Debate flares: Can obese patients be healthy?
■ Some heavy people might have healthy cardiovascular profiles, but research is necessary to determine if these numbers change over time.
By Victoria Stagg Elliott — Posted Sept. 1, 2008
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It's a frequent and challenging topic for exam room discussion -- do those extra pounds really undermine health and well-being? Now, a pair of studies in the Aug. 18/25 Archives of Internal Medicine has added to the discourse about whether someone can be fit and fat.
The studies upped the level of confusion and controversy by offering new evidence that some people who carry excess weight may have healthy cardiovascular and metabolic profiles while those considered at a normal weight may not have such rosy statistics. Nonetheless, experts still expressed caution about telling patients weight loss is unnecessary because it is unclear how the added bulk may affect these numbers over time. Also, the pounds often bring with them other health risks.
"Weight loss is important for all patients who are obese or overweight," said Lewis Landsberg, MD, who wrote an Archives editorial that accompanied these studies. He is director of the Northwestern University Comprehensive Center on Obesity in Chicago. "Even if one loses a small amount of weight, it definitely improves your risk factors and one's overall health, but not all obese people are at the same degree of risk."
One study, involving data from the 1999-2004 National Health and Nutrition Examination Surveys, found that almost 24% of those at a healthy weight had at least two metabolic abnormalities. These levels included low HDL cholesterol or high blood pressure, triglycerides, fasting plasma glucose or C-reactive protein. Approximately 51% of those who were overweight and 32% of those who were obese had healthy metabolic profiles.
"There's a large degree of heterogeneity in the metabolic consequences from the same amount of body fat," said Rachel P. Wildman, PhD, lead author and assistant professor of epidemiology and population health at New York's Albert Einstein College of Medicine. "And I think for a certain subset, the cardiovascular risks may not be as big as we thought."
The second study, this one by researchers at the University of Tübingen, Germany, reported the results of various tests on 314 patients. Those who were obese but insulin-sensitive had similar cardiovascular risk profiles to those who were of normal weight. Those who were obese and resistant to this hormone were at increased risk.
But experts say these studies do not exonerate excess weight as a health threat and should not change how physicians counsel patients. "From a practical standpoint, I don't think it changes our mantra at all," said Mott P. Blair IV, MD, a family physician in Wallace, N.C.
In both papers, a significant number of patients carrying excess weight still were at increased cardiovascular risk. In addition, these studies did not track outcomes. It's unknown how those with normal metabolic profiles but excess weight may fare over time. Wildman plans to investigate this issue in future projects.
"The idea that there are those who are obese and metabolically healthy appears to be true, but it's not a majority," said Dan Bessesen, MD, chief of endocrinology at Denver Health Medical Center. "And are these people really going to be healthy over the long haul? We're not sure."
These studies also did not track other health issues linked to extra weight, including an excess risk of cancer and joint problems. For example, another paper in the same issue of this journal found that being overweight increased the risk of recurrent venous thromboembolism by 27%.
"Even if there is not a cardiometabolic effect, obesity affects a person's life in so many ways," said Eric Westman, MD, associate professor of medicine at Duke University in North Carolina. He also is vice president of the American Society of Bariatric Physicians.
Watching the waist
Experts say the take-home message is that body fat is a more complicated issue than it appears, and the location of those pounds may be more important than the amount. The NHANES study found that those who were of normal weight but had a large waist circumference were more likely to have a poor metabolic profile. The German study found that those who were obese but had lower levels of fat in skeletal muscle or the liver were more likely to be heart healthy.
"It's not so much what we weigh. It's where we weigh," said Tim Church, MD, MPH, PhD, director of preventive medicine research at Pennington Biomedical Research Center in Baton Rouge, La.
For this reason, medical societies and public health agencies are increasingly promoting the measurement of waist circumference. American Medical Association policy encourages physicians to incorporate this vital sign along with a BMI calculation into the routine adult physical. Experts say it can be particularly helpful to identify and monitor those whose total weight is normal but may not be distributed in a healthy way. But many say that although physicians generally support this practice, anecdotal evidence suggests that measuring a patient's waist has not become widespread.
"Patients feel a little funny about it," Dr. Bessesen said. "They're not used to a physician coming at them with a tape measure."
Experts said these studies highlighted the importance of healthy behaviors, such as eating well and being active, over numbers on a scale.
"There are people in my practice who have a BMI of 25 to 30 who are actually very active and very fit," said Randy Rice, MD, a family physician in Moose Lake, Minn. "They're quite healthy, and they just cannot get the weight down. It's fine to keep active and not to get to hung up on just the weight."
The NHANES study linked physical activity to greater metabolic health. Also, a study published in the Dec. 5, 2007, Journal of the American Medical Association associated physical fitness, as determined by a treadmill exercise test, with a low risk of death, regardless of body weight.