Two new studies offer some solace to those who can't control their weight
despite diet and exercise by providing more evidence that genetics may play a
role in obesity.
One study offers unique insight because it finds genetic mutations in
severely obese children that suggest their excess weight may be more connected
to their DNA because they put on pounds at such a young age. The other study
found that certain genetic traits boost the risk of obesity in families.
The exact connection between genes and weight remains elusive. Still, "it's
very likely that many of the genetic variants that contribute to weight interact
with our environment - the food that we eat and the amount of exercise that we
get," said Sadaf Farooqi, professor of metabolism and medicine at the University
of Cambridge in the UK and co-author of the study on children. "In fact, some of
these genes act by influencing our appetite and how much we like food."
Previous research has shown that certain genetic variations boost the risk of
obesity, but not in everyone, said Daniel Belsky, a postdoctoral fellow at Duke
University's Center for the Study of Aging and Human Development. "Many people
who carry a high load of common genetic risks remain lean while others who carry
a light load of common genetic risks develop obesity," he said.
The two new studies, both published in the issue of the Journal
of Clinical Investigation, examine variations in the SIM1 gene that are
very rare but may have a big effect on the people who have them, Belsky said.
"The purpose of studying these variants is to learn something about obesity -
what systems are disrupted and how - with the aim of guiding the development of
new treatment and prevention strategies," he said.
In one study, researchers found several genetic mutations in 2% of 2 100
severely obese kids with an average age of 10, but in fewer than 0.1% of the
"When the genetic variations do occur, they play a major role in a person's
weight," study co-author Farooqi said.
What can people do?
In the other study, researchers studied the DNA of hundreds of children and
adults (many of them severely obese), as well as the DNA of children who seem to
have a condition called Prader-Willi syndrome, which can lead to overeating and
out-of-control obesity. Led by a researcher from the Lille Pasteur Institute in
France, the study authors linked three genetic mutations - related to those in
the other study - to a high risk of obesity in families.
Scientists suspect that the genetic variations in the studies affect hunger
and the way the body handles energy.
What can people do if their genes put them at higher risk of obesity? For
now, nothing beyond trying the usual weight-loss strategies, such as diet,
exercise and surgery.
"Despite this new discovery, there are still many genes to be found and we
still don't understand how some of these genes actually work to affect our
weight over long periods of time," Farooqi said. "If we can find new genes and
understand how they work, we may be able to find more appropriate treatments for
people who struggle with their weight."
For more about obesity,
try the US National Library of Medicine.