BMI by the numbers
Body mass index is an estimate of body fat based on height and weight.
Underweight = less than 18.5
Normal weight = 18.5–24.9
Overweight = 25–29.9
Obese = 30 or greater
On the Web: Find your own BMI using an online calculator.
Clark County obesity data tell health officials at least one thing: The county needs to go on a diet.
In Clark County, two-thirds of adults and a quarter of children are overweight or obese. Data from 2008 and 2009, the most recent period available, show that the county’s weight problem isn’t limited to one area. Each ZIP code has an overweight-or-obese rate of at least 52 percent.
The ZIP code with 75.9 percent, the highest rate, encompasses the Ridgefield area. The 98682 ZIP code, which covers the Orchards and Sifton areas, isn’t far behind, with 73.4 percent of residents overweight or obese.
The lowest rate, 52.6 percent, is in east Vancouver, roughly south of Mill Plain Boulevard.
The data come from an annual survey, the Behavioral Risk Factor Surveillance System, performed by the Washington State Department of Health with funding from the Centers from Disease Control and Prevention. The survey includes a random sample of hundreds of residents in each ZIP code.
“It’s designed to compare counties and states, and when you look at our obesity rates compared to Washington state, they’re about the same,” said Brendon Haggerty with Clark County Public Health.
“That’s not necessarily a good thing,” added Dr. Alan Melnick, county health officer.
But health officials caution against reading too much into the obesity-by-ZIP-code numbers. The sample size is small, meaning it could fluctuate year-to-year depending on who responded to the survey, Melnick said. In addition, data aren’t available in ZIP codes with too few survey respondents.
But by looking at the rates across the county and in other areas, health officials know obesity is connected to some characteristics, such as educational attainment, age and race, Haggerty said.
What the county has not been able to do is find the connection between obesity rates and the built environment. To do so, the county would need a larger sample size in order to break down rates by neighborhood, rather than ZIP code, Haggerty said.
Research elsewhere, however, has made the connection, he said.
A recent study looked at obesity rates in neighborhoods in Seattle and San Diego. The study also looked at those neighborhoods’ healthful food outlets and opportunities for physical activity.
The research found that the least “obesogenic” neighborhoods had many healthful opportunities — they were walkable neighborhoods, with high-quality parks and access to healthful food — while the most obesogenic neighborhoods had few healthful opportunities, Haggerty said.
In the least obesogenic neighborhoods, children had 59 percent less chance of being obese, the research found.
Those findings, while not specific to Clark County, can help health officials locally.
“What we can do is take studies like that and map the determinants in Clark County,” Haggerty said.
Armed with that information, Clark County Public Health has launched several programs to improve access to healthful food in neighborhoods.
Health officials also used the studies to guide policy recommendations for the county’s comprehensive growth management plan.
All of that information can help health officials tackle the obesity epidemic and make changes to reverse the trend, Haggerty said.
“The costs are concerning and they’re becoming a major driver in medical spending,” Haggerty said. “Treating obesity is vastly more expensive than preventing it.”