When fat and carbohydrates are combined in a single food they are more rewarding, calorie for calorie, than foods with either energy source alone, a Yale-led study published June 14 in the journal Cell Metabolism shows.
Fatty foods like cheese trigger one pathway of signals to reward centers in the brain while carb-loaded foods like grain or a lollipop take another route, said Dana Small, professor of psychiatry at Yale and senior author of the paper. "Our study shows that when the signals are combined they make foods more reinforcing."
What makes this finding interesting, says Small, is that foods high in fat and carbohydrate do not exist in nature with only one exception: breast milk. This makes sense, said Small, since it is important for infants to learn to suckle in order to survive.
" In the modern food environment that is rife with processed foods high in fat and carbohydrate like donuts, French fries, chocolate bars, and potato chips, this reward potentiation may backfire to promote overeating and obesity," Small said.
The research was conducted in conjunction with the Max Planck Institute for Metabolism Research in Germany. Alexandra Gold DiFelicenatonio of Yale is the first author of the study. Marc Tittgemeyer of Max Planck is co-senior author.