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But findings don't explain exactly how they are connected

By Randy Dotinga

HealthDay Reporter

MONDAY, June 17 (HealthDay News) -- 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 U.K. 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 June 17 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 percent of 2,100 severely obese kids with an average age of 10, but in fewer than 0.1 percent of the others.

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