Fat and carb rich foods preferred by the brain

By Dr. Ananya Mandal, MDJun 14 2018

We might all be aware of the harmful effects of junk food on health. This does not stop our brains from craving fat-rich and sugar loaded foods finds a new study. The study titled, “Supra-Additive Effects of Combining Fat and Carbohydrate on Food Reward,” was published today in the latest issue of the journal Cell Metabolism.

Image Credit: Brent Hofacker / Shutterstock

The researchers at the Max Planck Institute for Metabolism Research in Germany included 206 participants in this latest study. They found that the brain’s reward centres lit up when these participants were presented with foods that are high on fats as well as carbohydrates compared to when they were given foods rich in only carbohydrates. The fat and carbohydrate rich foods include French fries, chips, doughnuts, processed desserts and foods etc.

The participants were offered photographs of the food items of three categories – rich in fats and carbohydrates or containing mostly sugars and or containing only carbohydrates. Their brains were scanned using fMRI scanning while they looked at the pictures.

Results showed that the neurons at the reward centres of the brain lit up when the fat and carbohydrate rich foods were shown. The participants were asked if they would spend more money to buy these unhealthy options and most of them said they would.

Dana Small, senior author of the study and director of Yale University's Modern Diet and Physiology Research Center said that the study also asked the participants to estimate the calories that each of the food options contained and they noted that while they could nearly accurately estimate the calories from the fat content, they could not predict the calories from the carbohydrates in the foods offered. When fats and carbohydrates are combined, the brain considers the combo high on energy inaccurately, Small explained.

According to researchers, our brains are evolved from our ancestors who were seldom given foods rich in both carbohydrates and fats. They were mostly surviving on high carbohydrate diet supplemented with proteins and fats. So when faced with foods rich in both, the brain lights up. The team writes that this could be one of the causes for the obesity epidemic, since the brain when faced with foods such as these, can hardly resist.

This study is a continuation of earlier studies where laboratory rodents were given carbohydrates or fat alone. The animals tended to regulate their calories in that case. When they were given a combination of fats and carbohydrates, the animals gained weight more rapidly showing a lack of self-control.

Experts have explained that this study shows that while we like to think we are aware and in control of what we are eating, the brain wants something else. There seems to be a market for unhealthy food options because the brain still prefers these foods over healthy ones say researchers. They conclude that these results show that there is a stimulation of the brain’s reward centres in fat and carbohydrate rich foods and this “may be one mechanism by which a food environment rife with processed foods high in fat and carbohydrate leads to overeating.”