DNA-based diets may do little to help people avoid gaining weight, writes Tamar Haspel in a column at the Washington Post. While a person's genetic makeup likely does affect factors involved in weight gain — such as metabolic efficiency or eating behavior — she adds that the environment also plays a role.
The University of Cambridge's Giles Yeo tells Haspel that some 300 genes could influence people's tendency toward obesity. While he notes that researchers are still determining the effects of all those genes, Yeo says many of them exert influence on the brain. "Genetic propensity to obesity is a propensity to eat more," he tells her.
But all of this, Haspel says, is also influenced by lifestyle, medications, and socioeconomic status, and Clare Llewellyn from University College London tells her that the higher up the socioeconomic status someone is, the less that person's genes matter in terms of obesity risk. This, Haspel says, "tells us the environment is the difference between whether somebody dealt a lousy genetic hand gains weight or doesn't."
It also makes her skeptical regarding genetically tailored diets. "Since all these things are interconnected, never say never, but my crystal ball says personalized diets won't be any better than garden-variety, unpersonalized diets," Haspel predicts.