Dallas, TX - A special issue of Circulation released April 19, 2005 is focusing on the obesity epidemic, with the new Scientific Statement on Childhood Obesity by the American Heart Association (AHA) as the centerpiece for the issue.[1] This is the second time in as many months that the journal has put together a themed issue to highlight what the journal editors perceive to be an escalating crisis for people delivering cardiovascular care.

"Childhood overweight is one of our most critical public-health problems that threatens to ultimately reverse the favorable trends in cardiovascular morbidity and mortality that have occurred during the past half century," Dr Stephen R Daniels and his coauthors on the statement write. "Immediate action must be initiated to prevent excess weight gain and to treat those children and adolescents who are already overweight."

In a conference call timed to coincide with the release of the special issue, AHA president-elect Dr Robert H Eckel (University of Colorado, Denver) acknowledged that the scope of the problem has far outpaced anything in the way of treatments. He apologized tongue-in-cheek to journalists, saying, "I'm sorry we can't provide you with any cutting-edge new treatments for obesity." Instead, he said the aim of special issue of the journal was to highlight the complexity and extent of the obesity epidemic.

I'm sorry we can't provide you with any cutting-edge new treatments for obesity.

"In a sense, the take-home message from this journal is that we need to be increasing awareness and knowledge of the relationship between obesity and cardiovascular disease," Eckel told heartwire. "And at this point in time, we have to be increasingly intuitive and creative in our science to try to move this field forward."

Daniels agreed: "There has been a certain sense of fatalism about obesity, both preventing and treating it. And I think that what you begin to see in this package of papers is an emphasis on the importance of the problem but also some ideas that help emphasize that we shouldn't give up on this. This is something that physicians really should address early and often in their practices."

Other papers also featured in the special edition include studies examining whether fitness or fatness is the best predictor of CV risk, obesity and atherosclerosis development, waist circumference and triglyceride levels as a predictor of CV events in older women, and insulin resistance in overweight teens, among others.

The fitness-vs-fatness issue has been controversial, with some research suggesting that the benefits of being fit may outweigh the risk of excess pounds, while other studies have emphasized body weight over aerobic fitness. In their paper, Dr Demetra D Christou (University of Colorado, Boulder) and colleagues tried to tease out the relative importance of excess body weight and low/high aerobic exercise on CV risk in a group of men with a broad range of aerobic fitness levels, ages, and body fat.[2]

Habitual physical activity/aerobic fitness should be viewed as an effective partner to weight maintenance in the primary prevention of CVD, not as a surrogate approach.

They report that in 135 healthy men, BMI, percent body fat, and waist circumference were associated with all metabolic CV risk factors, while BMI and waist circumference were also independently associated with hemodynamic risk factors. Aerobic fitness, by contrast, was independently associated only with selective metabolic risk factors and not associated with any hemodynamic risk factors. Overall, the authors write, fatness was more strongly and consistently associated with CVD risk factors than aerobic fitness.

"Men who are overweight or obese should be encouraged to reduce body fatness, regardless of their aerobic fitness. Second, weight management and prevention of excess adiposity should be a primary cardiovascular health goal for men. Third, in lean trained men, the cardioprotective influence of habitual physical activity may be mediated in part through the maintenance of optimal body weight and fatness," the authors write. "Most important, our results support the position that habitual physical activity/aerobic fitness should be viewed as an effective partner to weight maintenance in the primary prevention of CVD, not as a surrogate approach."

The complex and often overlapping relationship between body weight and specific cardiovascular risk factors is the focus of several papers that attempt to clarify the association between markers of obesity and specific cardiovascular risk parameters. Andrea Cassidy (University of Michigan, Ann Arbor) and colleagues focused their efforts on atherosclerosis progression and report that obese subjects who were otherwise at low risk for cardiovascular disease had a significantly greater progression of coronary artery calcium than did underweight and normal-weight subjects.[3] Dr Alan R Sinaiko (University of Minnesota Medical School, Minneapolis) and his colleagues report that systolic blood pressure, fasting insulin, and triglycerides were higher and HDL was lower in overweight adolescents with insulin resistance, compared with thinner, insulin-sensitive teens, suggesting that insulin resistance in combination with fatness likely plays a role in the development of cardiovascular risk factors associated with the metabolic syndrome.[4] CRP levels were also highest in children with both insulin resistance and obesity, the authors noted.

Sinaiko elaborated during the conference call: "When we looked at fat kids who were also insulin resistant, their levels of risk were increased above what you'd expect from simply being insulin resistant and obese added together. . . . There was also the suggestion that the thin children who were insulin resistant had higher degrees of the risk factors than the thin children who were insulin sensitive. So I think the importance of this study—and what's unique—is that we're showing that insulin resistance seems to be independent to a certain degree from obesity."

He continued, "We all know that insulin resistance and obesity are related. The question always has been, what exactly is that relationship? And if you simply get rid of obesity, do you also get rid of the risk from insulin resistance? These data suggest that that may not be the case."

Several papers in the themed issue looked at weight in infancy or childhood in relation to obesity or cardiovascular disease risk later in life. Dr Nicolas Stettler (Children's Hospital of Philadelphia, PA) and colleagues report that weight gain during the first week of life appeared to be associated with overweight status in adulthood, among a cohort of 653 men and women in their 20s and early 30s.[5] Dr JK Cruickshank (Tulane Center for Cardiovascular Health, New Orleans, LA) et al report that lower birth weight among African American infants, compared with white infants, may account for ethnic differences in adolescent blood pressure, raising the possibility that improving intrauterine growth in black infants may help reduce hypertension later in life among African Americans.[6] Muddying the waters, however, Drs Debbie Lawlor (University of Bristol, UK) and David Leon (London School of Hygiene and Tropical Medicine, UK) examined BMI in 11 106 young children at a mean age of five years in relation to future risk of coronary disease and stroke and found no association between childhood BMI and later coronary disease.[7] "Further research in large prospective studies with repeated measures of childhood anthropometry from early childhood through adolescence are required to determine whether any association between overweight or obesity and CHD risk becomes apparent only in later childhood," they write.

Yet another study examined a simplified method for identifying cardiovascular risk level in postmenopausal women, using only waist circumference and triglyceride level. According to Dr László B Tankó(Center for Clinical and Basic Research, Ballerup Byvej, Denmark) et al, the "enlarged waist, elevated triglyceride (EWET)" method was a better predictor of fatal CV events than using the definition of metabolic syndrome, after adjusting for age, smoking, and LDL cholesterol.[8] "Presence of EWET was associated with a 4.7-fold increased risk and presence of metabolic syndrome was associated with a 3.2-fold increased risk for fatal CV events," the authors write. They conclude, "The combined presence of EWET may be the best indicator of cardiovascular risk in postmenopausal women. Other components of the [metabolic syndrome, National Cholesterol Education Program criteria] add little medical value to screening in general practices."

To the media, Tankó emphasized that he and his coauthors were not discounting the importance of smoking, high blood pressure, glucose levels, etc. "We propose this as a first-line investigation in general practices that have limited facilities, taking into account that should you refer all subjects with overweight and obesity to the healthcare system, it would be too expensive. So it's good to start with a cheap method that still captures at-risk patients fairly reliably," Tankó explained.

Asked whether the newly published collection of papers actually gives physicians new tools to deal with obesity or whether it should produce any radical practice changes, Eckel acknowledged that the new research does not provide concrete directions so much as it crystallizes the current knowledge. In some cases, however, the studies may help focus ongoing research. The Bogalusa Heart Study, for example, implies that care of pregnant mothers-to-be may have a direct impact on weight gain and blood-pressure changes in their offspring, Eckel noted.

Behavioral change is just so darn difficult.

More than anything, the AHA statement and accompanying papers should once and for all put paid to the exceptions made for childhood "puppy fat." As Sinaiko pointed out, "One of the things that we don't pay enough attention to is the fact that fat children become fat adults. We talk a lot about going through a growth spurt and that suddenly a fat child is going to get tall and thin out. But the fact is, if you follow children from early grade school until their young adulthood, you find there is an incredibly high correlation between their body mass indexes at both time points. So paying attention early on in life becomes even more important."

He points out that a consistently high BMI is associated with an increased level of other cardiovascular risk factors. "The question of what can we do about it is the major question, because behavioral change is just so darn difficult. How do you get people to lose weight, to exercise, especially children? That's what we're all struggling with. But the fact is, it starts early in life."