Obese people face a higher risk of passing
out - or worse - during heat waves, some health experts say.
Layers of fat make
it extra difficult for a body to dissipate heat, or to move to a cool location.
Add in diabetic dehydration and other conditions common in the obese, and it's a
recipe for trouble.
"ER physicians will tell you that they (obese people) are the ones
collapsing," said Thomas Adams, a Michigan State University physiologist.
Federal health officials list obesity as a risk factor for heat-related
illness, but health warnings generally focus on the dangers to children, the
elderly and the socially isolated. Those are the groups considered most in
danger of fatal heat stroke, health officials said.
But non-fatal heat exhaustion may hit obese people more quickly than thinner
folk, said Adams, author of the 1993 book 'Guidelines for Surviving Heat and
Cold.'
Fat is a natural insulator that traps core body heat, experts said. While
that may be a boon in the winter, it's a burden for someone stuck in summer
heat.
The body cools itself by circulating blood to dissipate heat through the
skin. A heavy person's heart must pump harder to circulate blood on a hot day.
When a person is standing up, the most difficult place to circulate blood to
is the brain. So inadequate circulation can cause someone to be lightheaded and
to faint, Adams explained.
People also cool off by sweating. An obese person who cannot dissipate heat
through circulation will sweat more, meaning they lose water and body salts to
become more quickly dehydrated, he added.
The risk of heat-related death seems to rise with the degree to which a
person is overweight, but scientists haven't determined at what level of being
overweight the danger truly escalates, said George Luber, an epidemiologist with
the U.S. Centers for Disease Control and Prevention.
In the years 1999 through 2003, about 1,200 U.S. deaths were reported in
which heat-related illness was a major factor, according to a CDC report
published last week. The report did not examine obesity as a risk factor, but
found cardiovascular disease was an underlying cause of death in 57% of those
cases and diabetes was in 3% of those cases.
"People who are obese tend to suffer more from cardiovascular disease," noted
Luber, who co-authored the report. "Obesity kind of represents several risk
factors rolled into one."
Everyone is at risk during a severe heat wave, but it makes sense for obese
people to be cautious, said Dr. Arthur Kellermann, a professor of emergency
medicine at Atlanta's Emory University.
"If they read this article and say 'Well I am kind of heavy, I should be
careful,' that's good," Kellermann said.
