Three o' clock hits and your brain starts searching to fill the speed bump of relentless exhaustion in your day by craving a sweet, sugary snack. What’s going on in your brain is more serious than the daily late afternoon chocolate bar, however. Overeating and food addiction are one of the greatest public health problems in America today, forcing scientists to lock themselves into their labs and find a solution. There must be clues hidden along the pathways of our neural circuitry, thought the researchers from the Massachusetts Institute of Technology. Once they traced the wiring of the brain to the source of compulsive sugar consumption in mice, it marked the first step in unraveling the mystery of overeating.

The addiction to food and activity of eating itself engages the same type of reward-seeking behavior as drug addiction in the brain. By looking at the reward-related circuits in mice brains as they consumed sugar, researchers were able to comb through the intricacy of circuits to find the exact pathway. Before they even began, the study’s lead researcher Kay Tye, from MIT, and her team believed their answer was in a part of the hypothalamus, so they tested the theory by lighting up brain pathways in mice. Their findings appear in the journal Cell.

"Although obesity and type 2 diabetes are major problems in our society, many treatments do not tackle the primary cause: unhealthy eating habits," Tye said in a press release. "Our findings are exciting because they raise the possibility that we could develop a treatment that selectively curbs compulsive overeating without altering healthy eating behavior."

The mice were well-fed and each one of their brains was monitored when they entered into the experiment tank. Sugar rewards were placed in one section to entice the mice; however, the platform they had to cross delivered foot shocks. Those mice who had the hypothalamus circuits turned on went after the sugar despite the shocks, and those mice who had those circuits turned off didn’t risk the pain for the sugary reward. What if that same group of neurons could be simply turned off in a human brain? They would no longer emotionally torture themselves with guilt to get to that last pint of ice cream stored in the freezer.

Our innate desire to consume sugary foods out of desperation is a product of biological evolution. Whenever valuable nutritious food sources were scarce or unavailable, the brain would desire sugar to fulfill an instinctual survival need. But we no longer have to fear scarcity of certain foods in the wintertime, which means the system is obsolete. Instead, it’s making more than 78.6 million Americans obese, according to the Centers for Disease Control and Prevention.

"However, in our modern day society, there is no scarcity of palatable foods, and high-sugar or high-fat foods are often even more available than fresh produce or proteins," Tye said. "We have not yet adapted to a world where there is an overabundance of sugar, so these circuits that drive us to stuff ourselves with sweets are now serving to create a new health problem. The discovery of a specific neural circuit underlying compulsive sugar consumption could pave the way for the development of targeted drug therapies to effectively treat this widespread problem."

Source: Tye K, et al. Decoding Neural Circuits that Control Compulsive Sucrose-Seeking. Visualizing hypothalamic network dynamics for appetitive and consummatory behaviors. Cell. 2015.