TUESDAY, Nov. 17 (HealthDay News) -- Surging obesity rates, especially among children, may be putting the brakes on progress made in the past few decades against heart disease, researchers report.

And it doesn't help that many obese or overweight Americans still consider their weight "normal," as one study found.

One of several studies on the subject of obesity presented Tuesday at the American Heart Association (AHA) annual meeting in Orlando, Fla., found that adults' blood pressure and blood sugar levels are continuing to rise, fueled in large part by expanding waistlines.

This is swamping recent heart-health improvements such as lowered blood levels of LDL ("bad") cholesterol or fewer people smoking, experts said.

Poring over government data between 1988-1994 and 2005-2006, researchers found that adult Americans' average body mass index (BMI) rose from 26.5 to 28.8 over that time span. To put that in context, a BMI of 25 marks the beginning of overweight, while doctors use a BMI of 30 as the threshold for obesity.

More people did achieve optimal LDL levels (22 percent versus 28 percent) and were non-smokers (rising from 45 percent to 50 percent) during the same time period, but those gains were outweighed by fewer people having good blood pressure (48 percent versus 43 percent) or blood sugar control (falling from 67 percent to 58 percent).

In fact, "many people feel the decline in [heart] risk factors is leveling off and there will be an acceleration of cardiovascular disease," said AHA spokesman Dr. Roger Blumenthal, professor of medicine in the division of cardiology at Johns Hopkins School of Medicine in Baltimore.

Things don't bode well for the next generation, either: U.S. Centers for Disease Control and Prevention statistics now put the number of obese children and teens in the United States at about one-third.

"The prevalence of obesity and oversight in the U.S. and all developed countries is on the rise and reaching epidemic proportions among both adults and children," said Dr. David Crowley, lead author of a study on child obesity and a cardiology fellow at Cincinnati Children's Hospital. "In the course of the past three decades, the prevalence of obesity has doubled or in some cases tripled across all pediatric age groups."

Not only have children and teens become heavier, their hearts have become unhealthily thicker, as measured by left ventricular mass (LVM), indicating a higher risk for heart disease down the line.

"Left ventricular mass is a marker of stress on the heart and a predictor of heart attack and stroke," Crowley explained.

Between the mid-1980s and today, average BMIs in this sample of children went from 18.1 to 19.9, while LVM jumped from 31.4 to 32.7. Males and blacks fared worse than their female and/or white peers.

There were nearly twice as many overweight and obese children in the later period compared to the earlier era: 35 percent versus 20 percent. And the number of children with abnormally thick hearts more than doubled, Crowley reported.

"The obesity epidemic is indeed having adverse effects on the hearts of children compared to two decades ago," he said. "Today's children have higher BMI and higher LVM and therefore are at a higher risk of heart attack and stroke. If we do not get a handle on this in this country, if kids continue to get heavier, their hearts will inevitably get thicker and kids will be at higher risk of heart attacks and stroke."

Simple denial may be a component of this disaster, speculated a third study. It found that a large proportion of obese people believe their body size is normal and that they don't need to shrink. Some even believe they could safely gain more weight.

Almost one in 10 surveyed said they were okay with the size of their bodies after picking from a series of silhouettes the one they felt best represented their image of themselves.

This same group also thought they were healthy, even though many of them had risk factors for heart disease such as diabetes or high blood pressure.

Ironically, individuals who were actually average or thin thought they were larger than they really were.

"Obesity is not benign," noted study lead author Dr. Tiffany Powell, a cardiology fellow at the University of Texas Southwestern Medical Center in Dallas. "This underscores the need for us as physicians to understand that we not only need to target those who have misperceptions in clinical settings, but we also need to do work at developing community programs targeting those who avoid the health-care system," Powell said.

"From our data, it looks like those who have misperceptions of body size are much less likely to be seen by physicians," she added.

Two other groups of researchers at the AHA meeting presented yet more reasons to lose weight. In one study, obese patients who lost weight saw a healthy normalization of the chambers in the right side of the heart (although it's unclear if this results in decreased risk for actual heart problems). And in another study, weight-loss surgery reduced the size of enlarged hearts. Enlarged hearts carry with them the risk of heart failure.

More information

There's more on obesity's impact on heart disease at the American Heart Association.

SOURCES: David Crowley, M.D., clinical fellow, cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati; Tiffany Powell, M.D., cardiology fellow, University of Texas Southwestern Medical Center, Dallas; Roger Blumenthal, M.D., AHA spokesman and professor, medicine, division of cardiology, Johns Hopkins School of Medicine, Baltimore; Nov. 17, 2009, presentations, American Heart Association annal meeting, Orlando, Fla.

Copyright © 2009 ScoutNews, LLC. All rights reserved.