About 24 percent of Canadians are obese compared to more than 34 percent of Americans, according to the U.S. Centers for Disease Control and Prevention study released Wednesday.

Researchers looked at height and weight data taken in surveys in both countries during 2007-09.

The two countries have different racial demographics. The United States has more black and Hispanic people, and both have higher rates of obesity. But even looking solely at white people, there was still a big difference — a 26 percent obesity rate in Canada compared to 33 percent in the United States.

It’s not clear why that is, said study-co-author Cynthia Ogden, an epidemiologist with the CDC’s National Center for Health Statistics.

“We share this border and many other things. It’s a question we need to investigate more,” said Ogden, whose co-authors included a researcher at Statistics Canada.

Another mystery: In children there was little difference. The childhood obesity rate was 15.5 percent in the United States and 12 percent in Canada, but the difference was not statistically significant.

This study is the first time the CDC has compared American obesity rates with another country. The report adds to a growing pile of studies that show Americans are less healthy than people in other developed nations.

For example, a 2006 Harvard Medical School study found that Americans are 42 percent more likely than Canadians to have diabetes, 32 percent more likely to have high blood pressure, and 12 percent more likely to have arthritis.

That study, based on telephone interviews rather than actual measurements, found about 21 percent of Americans said they were obese, compared with 15 percent of Canadians. That finding suggests Canadians and Americans share one characteristic — they tend to understate their heft.

While just 13 percent of adults were obese in the early 1960s, more than 30 percent were by 1999. In Healthy People 2010, a series of health objectives published in 2000, the U.S. government set forth the goal of reducing the percentage of obese Americans to 15 percent by 2010.

To investigate trends over the past decade, and determine whether the U.S. had any chance of meeting this objective, Dr. Earl S. Ford and his colleagues from the CDC’s National Center for Chronic Disease Prevention and Health Promotion looked at data on nearly 23,000 people aged 20 and older from the National Health and Nutrition Examination Survey for 1999-2008.

In 1999-2000, the researchers found, 27 percent of men were obese and 39 had abdominal obesity. By 2007-2008, those percentages had risen to 32 percent and 44 percent, respectively. The number of obese women inched up from 33 percent to 35 percent over the same time period, while abdominal obesity prevalence rose from 56 percent to 62 percent.

Abdominal obesity, defined as having a waist size of about 35 inches for women and 40 inches for men, has been tied to a wide range of health problems, including heart disease, diabetes, and high blood pressure.

Average body mass index (BMI) — a measure of weight in relation to height used to gauge whether a person is at a healthy weight — also increased. Men’s average BMI increased from 27.8 to 28.5. For women, average BMI rose from 28.2 to 28.6.

“The prevalence of obesity and abdominal obesity remains disturbingly high among adults in the United States, and our trend analysis shows that both may still be increasing among men,” Ford and his colleagues write in the International Journal of Obesity.

The rising tide of obesity “has all but ruled out” the chances that the U.S. will meet its Healthy People 2010 goals, they add, noting that public health officials are now at work on developing new goals for Healthy People 2020.

In order to whittle U.S. obesity rates down to 15 percent, Ford and his team say, the average American would either need to consume 500 fewer calories a day, walk for nearly two additional hours a day, or burn off the equivalent amount of calories doing some other type of physical activity.

“The path to achieving such changes in energy intake and physical activity is unlikely to be an easy one,” the researchers conclude.

SOURCE: http://link.reuters.com/buw74p, International Journal of Obesity, online September 7, 2010.

Of course that still means that the majority of Americans are currently overweight and at high risk of chronic health problems, such as heart disease, diabetes and certain cancers. These risks continue to propel several national campaigns aimed at preventing obesity, particularly in children, including those spearheaded by First Lady Michelle Obama and former President Bill Clinton. But some researchers say such programs, which involve school-age children, may begin too late to benefit all children. (See a special report on the science of appetite.)

Increasingly, evidence suggests that obesity-prevention measures need to be taken earlier, in infancy or even before birth. According to the CDC’s National Health and Nutrition Examination Survey, rates of obesity in youngsters ages 2 to 5 have more than doubled since 1980, from 5.0% to 12.4%. And once a child sets down the road to an unhealthy weight, it becomes increasingly difficult for him to change course: according to one study, 80% of children who are overweight between ages 10 and 15 grow up to become obese 25-year-olds.

In November 2009, with funding from the Robert Wood Johnson Foundation, the Institute of Medicine (IOM) formed the Committee on Obesity Prevention Policies for Young Children, whose members will for the first time review evidence on obesity risk factors and health effects in children from birth to 5 years old and identify potential opportunities for intervention in this age group. The committee’s first report is expected in early 2011. (See five key questions about weight loss.)

Early Warning Signs
In a recent study of more than 1,800 children, who were tracked from before birth to age 4, Harvard researchers identified several risk factors for obesity that began in pregnancy or early childhood. They included pre-pregnancy obesity; gestational diabetes; low birth weight and rapid weight gain in infancy; stopping breast-feeding early; introducing solid foods before 4 months; short sleep in infancy; TV in children’s bedrooms; and higher consumption of fast food and sugary beverages in childhood. In many cases, these early risk factors were more common in black or Hispanic families than in white families, regardless of income.

The findings, first published online on March 1 by the journal Pediatrics, help explain why minority children are at higher risk for obesity early on: 16.7% of Mexican-American children ages 2 to 5 are obese, compared with 14.9% of black children and 10.7% of white children, according to CDC data. The authors emphasize that obesity prevention must not only begin early, but also address cultural issues and include education targeted to specific groups. The good news, says study author Dr. Elsie Taveras, an assistant professor of pediatrics and prevention at Harvard Medical School and a member of the IOM obesity committee, is that many risk factors involve behaviors than can be modified and are not due only to socioeconomic inequalities. “As a pediatrician, it’s frustrating for me to think, How am I going to change this person’s household income? But what a hopeful message to know that it’s actually not that in many cases,” she says. (See a slideshow about obesity rehab for teens.)

A Tipping Point for Obesity?
How early in life that prevention efforts need to target children is quickly becoming a central question to childhood-obesity research. One intriguing notion is that there exists an obesity threshold – or tipping point – in infancy, before which a chubby child may be safely steered away from a lifetime of obesity. A small study led by Dr. John Harrington, an associate professor of pediatrics at Eastern Virginia Medical School and Children’s Hospital of The King’s Daughters, analyzed childhood medical records of 111 obese children and adolescents – those with a body mass index (BMI) equal to or higher than 85% of their same-age peers – in order to determine the age at which children first became overweight.

On average, researchers found, overweight individuals first crossed the threshold into overweight territory before 22 months of age. In some kids it was even earlier, with about 25% of children already having gained more weight than recommended for their age and height at 3 months. The trajectory typically began early and remained consistent: the BMI of overweight children continuously diverged from that of normal-weight children, the difference increasing by 0.072 units per month starting at birth and crossing the 85th-percentile mark at about 21 months. Within the small sample, half of the overweight children became overweight before age 2, and 90% became overweight by age 5. “You’ve got to look at it in terms of intervention and prevention,” Harrington says. “If you’re trying to intervene at age 5, you’ve already missed the boat.” (See why we get fat.)

Part of the problem is that parents and pediatricians tend to overlook early signs of obesity. Many people view children with excess baby fat as healthy, and believe they’ll shed the weight as they grow. Harrington advises physicians to start screening babies earlier for immoderate weight gain and to broach the topic sooner with parents. There’s a lot parents can do at home to encourage healthy weight in their children, Harrington says, and making even one or two small changes can lead to lowered risk. For instance, Harrington advises parents to adhere to infants’ own cues for fullness and hunger, rather than encouraging them to eat more. And toddlers are “grazers,” so it’s perfectly healthy for them not to conform to an adult schedule of three square meals per day, he says.

Harrington’s study, first published online in February by the journal Clinical Pediatrics, suggests that the optimal age for instilling healthy eating and activity behaviors is before age 2. As children get older, it becomes more difficult to unlearn behaviors and reverse the trend, Harrington says. “The first thing to do is to recognize that there’s a problem and to see that maybe it didn’t start at age 4 or 5, or 6 or 7, but maybe before then,” he says. “The longer you’re overweight, the more likely it is that you’re going to be overweight as an adult.” (Read about the bugs in your gut.)

Getting a Head Start
Not all chubby kids grow up to be overweight adults; indeed, many heavy babies do shed their baby fat and remain slim thereafter. Determining which children are at higher risk, however, is easier said than done. The study that could answer that question has not yet been conducted. “The only way to do that is to do a prospective study of 10,000 kids, following them from birth to see what their trajectories are,” Harrington says. One such study is in the works – the National Children’s Study, which aims to follow 100,000 babies from the womb to age 21, was authorized by Congress in 2000 – but results from that research are still years away. (Read about good fat.)

For now, researchers say national childhood obesity prevention and education efforts should include families with newborns and toddlers, and promote healthy habits starting in pregnancy or earlier. Even seemingly minor actions, such as reminding pregnant women that they should not in fact be “eating for two” – in spite of their grandmother’s best advice – could reduce children’s chances of becoming obese, says Taveras. “Some of these things become so embedded in our thinking that they actually become our standard of care for our children,” she says. “If we really try to start focusing on prevention earlier, we might have a greater impact.”

White women with higher incomes and private health insurance were the most likely to have the surgery, according to a study to be presented Wednesday at the American Society for Metabolic & Bariatric Surgery (ASMBS) annual meeting, in Dallas.

Using data from the 2006 Nationwide Inpatient Sample, sponsored by the U.S. Agency for Healthcare Research and Quality, researchers identified 88,000 morbidly obese adults who had bariatric surgery in the United States in 2006.

Of those, 81 percent were women, 75 percent were white, 80 percent had incomes at least two times the poverty level and 82 percent had private health insurance.

Although government statistics show that blacks make up 18 percent of morbidly obese adults, they represented only 11 percent of people getting bariatric surgeries, the team noted.

“The socioeconomic differences we found were pretty striking,” said Dr. Matthew J. Martin, an assistant professor of surgery at Madigan Army Medical Center in Tacoma, Wash. “Income, race, insurance status, and even your gender, are potential barriers to access to surgery.”

Morbid obesity was defined as having a body-mass index (BMI) over 40, or a BMI of 35 to 40 with an obesity-related disease such as type 2 diabetes, heart disease or sleep apnea, criteria established by the U.S. National Institutes of Health.

Despite a growing body of evidence that bariatric surgery is among the most effective long-term treatments for severe obesity, few actually undergo the procedure, which costs an average of between $17,000 to $26,000, according to the ASMBS.

In fact, less than one-half of 1 percent of the more than 22 million people in the U.S. who are medically eligible for bariatric surgery actually go through with it, according to statistics derived using data from the National Health and Nutrition Examination Survey (NHANES).

Socioeconomic disparities in health care are common in other types of medical conditions, including cancer and cardiovascular treatments. Lack of access to health care is one reason why the poor tend to have worse health overall than the rest of the population, Martin said.

Obesity seems to strike lower-income people more than the more affluent. About 35 percent of the morbidly obese had a household income that was less than two times the poverty level, the study found, compared to 28 percent of the general population.

About 15 percent of the morbidly obese had incomes below the poverty level, a benchmark that varies depending on household size and geographic region.

The morbidly obese were also more likely to have no insurance of be underinsured, defined as having coverage from Medicaid or other government-subsidized healthcare. About 20 percent of the morbidly obese were underinsured, compared with 8 percent of the general population.

Women and blacks also made up a disproportionate amount of the morbidly obese compared to their proportion of the population as a whole.

Nearly 30 percent of those who had bariatric surgery also had diabetes, 52 percent had hypertension and 19 percent had chronic pulmonary disease. The morbidly obese took twice as many sick days per year (5.4 vs. 2.8) and missed more work days (8 vs. 5).

“Increasing access and breaking down the socioeconomic barriers to bariatric surgery among the underserved population has the potential to significantly impact the health and well-being of millions of people throughout the U.S,” Martin said.

While Medicaid and government-run medical plans do cover bariatric surgery, patients often have long wait times for approval and often are denied coverage for seemingly arbitrary reasons, added ASMBS President Dr. Scott Shikora.

Even after a surgeon, mental health professional, dietician and physician who specializes in obesity has determined the patient should have bariatric surgery, the patient is told to try six months or a year of additional, medically supervised weight loss attempts before trying surgery, Shikora said.

“In our area, it’s difficult for patients with Medicaid to get approval even if they meet all of the criteria,” said Shikora, director of Weight and Wellness Center at Tufts Medical Center in Boston. “They seem to arbitrarily reject applications, require lots of paperwork and take a long time to approve anything.”

Another study also scheduled to be presented Wednesday found that weight loss surgery may work just as well for older patients as it does for younger ones. Researchers found that morbidly obese seniors age 65 and older who had laparoscopic gastric bypass surgery lost about 76 percent of their excess body weight and had no more complications than younger patients.

“Bariatric surgery in the older population is underutilized because of a misperception that old age alone puts patients at higher risk for complications and mortality, said Dr. Joseph Kuhn, MD, study co-author and director of General Surgical Research at Baylor University Medical Center in Dallas. “We found seniors can benefit just as much as younger people from bariatric surgery without taking on additional risk.”

Despite a higher prevalence of surgical risk factors such as sleep apnea, type 2 diabetes and hypertension, 100 patients aged 65 to 77 with an average BMI of 45 had hospital stays and complication rates that were comparable to younger patients, the team found.