Obesity More Complex than We Think?
10 Possible Causes of America's Obesity Epidemic -- Besides Gluttony and Sloth
June 27, 2006 -- Obesity isn't all about eating and inactivity, says an
international group of researchers.
Just about everywhere you look, doctors are blaming America's obesity
epidemic on two things: too much food -- especially widely marketed fast food
and junk food -- and too little exercise, with too much time in front of the
But we're paying too much attention to the "big two," argue David B.
Allison, PhD, director of the University of Alabama at Birmingham clinical
research center, and his colleagues.
"The importance of the big two is accepted as established, and other
putative factors are not seriously explored," they argue. "The result
may be well-intentioned but ill-founded proposals for reducing obesity
To stimulate debate, Allison and colleagues suggest 10 other possible causes
of obesity. Their article appears in this week's online edition of the
International Journal of Obesity.
It's well accepted that reduced physical activity and fast food are linked
to obesity. But the evidence that these are the main causes of obesity
is "largely circumstantial," Allison and colleagues say.
Obesity researchers should broaden their horizon, they argue. So the
researchers propose 10 other explanations for obesity, which are also supported
by circumstantial evidence.
Even if some of these causes have only a small effect, Allison and his
colleagues say, they may interact in ways that greatly magnify their individual
10 Causes of Obesity
The researchers put forth these 10 "additional explanations"
- Sleep debt. Getting too little sleep can increase body
weight. Today's Americans get less shut-eye than ever.
- Pollution. Hormones control body weight. And many of
today's pollutants affect our hormones.
- Air conditioning. You have to burn calories if your
environment is too hot or too cold for comfort. But more people than ever live
and work in temperature-controlled homes and offices.
- Decreased smoking. Smoking reduces weight. Americans smoke
much less than they used to.
- Medicine. Many different drugs -- including
contraceptives, steroid hormones, diabetes drugs, some
antidepressants, and blood pressure drugs -- can cause weight gain. Use of
these drugs is on the upswing.
- Population age, ethnicity. Middle-aged people and
Hispanic-Americans tend to be more obese than young European-Americans.
Americans are getting older and more Hispanic.
- Older moms. There's some evidence that the older a woman
is when she gives birth, the higher her child's risk of obesity. American women
are giving birth at older and older ages.
- Ancestors' environment. Some influences may go back two
generations. Environmental changes that made a grandparent obese may
"through a fetally driven positive feedback loop" visit obesity on the
- Obesity linked to fertility. There's some evidence obese
people are more fertile than lean ones. If obesity has a genetic component, the
percentage of obese people in the population should increase.
- Unions of obese spouses. Obese women tend to marry obese
men. If there are fewer thin people around -- and if obesity has a genetic
component -- there will be still more obese people in the next generation.
"We do not claim that all of the additional explanations definitively
are contributors [to obesity] but only that they are as plausibly so as are the
'big two' and deserve more attention and study," Allison and colleagues
And the researchers' list of 10 doesn't exhaust the possibilities. There may
be even more explanations, including: a fat-inducing virus; increases in
childhood depression; less
consumption of dairy products; and hormones used in agriculture.