New research from the UK does suggest that. The theory is that certain genetic variants increase the brain’s responses to particular foods, prompting you to eat more of them than others would. People with these variants “may experience more cravings than the average person when presented with high-calorie foods … those high in fat or sugar,” researcher Tony Goldstone of Imperial College London reported at a November (2015) meeting of the American Society for Metabolic and Bariatric Surgery and the Obesity Society.
Dr. Goldstone and his team found that two gene variants influence activity in the brain’s reward system when people view images of calorie-dense food. They reported that the variants are located near a gene (named FTO) that has been linked to an increased risk of obesity. The variants are also associated with the DRD2 gene. The DRD2 variant identified in the study alters how the neurotransmitter dopamine works in the brain. Dopamine is key because its signals can intensify cravings in response to foods high in fat and sugar.
The researchers used functional MRIs to measure brain activity when people viewed high-calorie foods. They observed greater activity in those with the genetic variants than in the others in the study. In addition to the responses seen on the brain scans, the researchers asked the participants to rate how appealing they found the foods they viewed.
Earlier findings have also linked obesity with genetic variants. We learned from a Swedish study published in 2013 that the extremely obese have a greater number of gene variants that may increase the risk of obesity, but they do not necessarily have completely different genes from those associated with other weight ranges. The investigators in that study examined the relationship between different body measurements and 2.8 million gene variants in 168,267 study participants. They found that the genetics underlying extreme obesity are similar to those that cause milder forms of overweight and obesity.
The more we learn about obesity from genetic research, the better able we should be to find ways to prevent and treat it. Bear in mind, however, that genetic factors are believed to be responsible for only about five percent of all cases of obesity. Genetic changes in human populations come about very slowly and are not likely to blame for the obesity epidemic. Primary causes may include environmental and societal changes that make it easier to overeat and more difficult to get the physical activity that kept weight under control in previous generations.
Andrew Weil, M.D.
Anthony Goldstone et al, “Energy density influences interaction between FTO and DRD2 gene variants in brain reward system responses to food evaluation.” (Paper presented at the Obesity Society Annual Meeting, November 5, 2015 Los Angeles, CA.)