Whodunnit: TV or Fast Food or Genes?

When it comes to obesity, no one explanation tells the whole story.

By Jennifer Barone|Tuesday, June 03, 2008

The blame game for obesity (was it your parents or those cupcakes?) continues to escalate. Two recent studies—one in mice and another in humans—provide new evidence that a mind-numbingly complex array of genes influence body weight. By sampling fat tissue, one group of researchers found that the activity of 17,000 genes correlate with body mass index (a measure of body fat based on height and weight), and 14,900 correlate with waist-to-hip ratio. Complicating matters further, these genes seem to operate in large networks, interacting with each other and the environment to influence weight.

So should you blame genes—with labels like Lpl, Lactb, and Ppm1l—or fast food and failure to exercise for your weighty woes? The top researchers say they still don’t know.

Data from identical twins going back as far as the 1930s suggest that body weight is at least partly inherited, but only in recent years have scientists begun to appreciate the complexity of the genetic factors underlying obesity. Robert Kushner, a specialist in obesity medicine at Northwestern University, says that identifying the interacting genes will help screen those at risk, but far more research is needed before pharmaceutical interventions might emerge.

And even then, no one thinks that genetic testing or manipulation will ever lead to a catch-all cure. George Bray, who heads the clinical obesity and metabolism department at Louisiana State University, says environment and behavior—like lack of access to exercise facilities and overeating—so strongly affect gene activity that you cannot focus on one while ignoring the other. Both experts agree that addressing energy balance—the number of calories consumed versus the number used in physical activity—is a good starting point for anyone struggling with obesity. Research continues, but holding out for a miracle weight-loss drug is probably not the answer. As Kushner puts it, “a magic bullet is highly unlikely.”

Comment on this article