(CNN) -- The need for firefighters to be fit seems obvious: A fire ax weighs around 20 pounds, and an oxygen tank can be up to 50. Throw in the big boots, jacket, unruly fire hoses and challenging emergencies, and you'd expect most firefighters to be in peak physical condition.
You'd be wrong. More than 70% of domestic firefighters are overweight or obese, a rate slightly higher than the general population, according to a recent study from the Centers for Disease Control and Prevention.
"It's tough. Firefighters are humans too. And just like the American public is having a hard time battling obesity and being overweight, firefighters are having the same troubles," said Dr. Sue Day, author of the CDC report and an associate professor of epidemiology at the University of Texas School of Public Health.
Those extra pounds are taking a toll.
Cardiovascular events account for nearly half of the deaths of on-duty firefighters, and obesity has been linked to an increased risk of job-related disabilities, according to the CDC.
"Firefighters have extremely tough and stressful jobs," Day said. "But these are our first responders. They need to be cared for, and they need to be fit.
"There needs to be more collaboration in giving guidelines to people to change behavior."
A tough sell
There are no nationally enforced standards on physical health and wellness for U.S. firefighters, says Kimberly Quiros, director of communications for the National Volunteer Fire Council. Prospective firefighters are forced to demonstrate that they can handle the job's physical toll, but those initial tests are the only nationalized benchmark.
Once a firefighter is accepted, fire departments have been historically lax in maintaining a fitness regimen, something the national council is looking to change.
The organization collaborates with the National Fire Protection Association to release a set of guidelines promoting healthy, positive behaviors in fire department members. The most recent version of these standards was released last year.
"These are standards, but they're not laws," Quiros said. "Ideally, all departments in the nation would adopt this."
But buy-in remains an issue, she says, citing time constraints and limited budgets. About 71% of fire departments in the United States are made up solely of volunteers, according to the U.S. Fire Administration.
"Some are worried that if they enforce physical standards, they'd lose half their firefighters," Quiros said. "We're working to get past that culture and make sure it's a priority to keep them healthy."
Quiros points to a chaotic, almost manic daily schedule as one of several reasons that firefighters are likely to become obese on the job. Not only are firefighters more likely to eat fast food, but these men and women are routinely placed in high-stress situations.
"(Firefighters) are eating on the go and getting sleep patterns disrupted," she said. "And many times, firefighters may just assume that their natural physical activity and lifestyle will keep them healthy, but that's not enough to balance it out."
Changing the culture
After 39 years in the volunteer fire service, Kevin Quinn knows a thing or two about a heated battle.
So 10 years ago, as deputy fire chief in South Kingstown, Rhode Island, Quinn decided to wage a new fight against obesity in his department.
"We set up a health and wellness community and pushed full buy-in from the start," he said. "Each of our stations had their own health initiatives, maybe stair climbs, fitness runs or Tough Mudders. ... We wanted to create a sense of pride surrounding fitness.
"We knew most of these firefighter on-duty deaths are preventable."
Quinn, now retired, merged eight previously separate units into one large physical fitness center. At department meetings, he replaced the pizza with fruits and vegetables, and he even began sending younger members to firefighter physical health conferences.
According to Quinn, the Union Fire District in South Kingstown has since seen a reduction in smoking and alcohol consumption among its firefighters, coupled with substantial weight loss.
He now works with the National Volunteer Fire Council.
"Providing better choices was critical," he said. "We realized that if you put apples and oranges in front of them, our firefighters weren't going to them."
"We've learned to precut the fruit."