The human brain values foods that are high in both fat and carbohydrate than those containing either fat or carbohydrate alone, researchers say.

These foods tend to hijack body's inborn signals governing food consumption. Thus, our brain's rewarding system -- group of neural structure responsible for motivation, desire, craving for reward -- is more likely to chose them, a reason why people feel difficulty in losing or keeping off excess weight, the researchers explained.

"Surprisingly, foods containing fats and carbohydrates appear to signal their potential caloric loads to the brain via distinct mechanisms," said Dana Small from the Yale University in the US. "Our study shows that when both nutrients are combined, the brain seems to overestimate the energetic value of the food," Small added. The study published in the journal Cell Metabolism, analysed data from 206 adults. The participants underwent brain scans while being shown photographs of familiar snacks containing mostly fat, mostly sugar, and a combination of fat and carbohydrates and were allocated little amount of money to bid on their first-choice food.

The results showed that the participants were willing to pay more for foods that combined fat and carbohydrates. The researchers noted that the results may help explain brain-body mechanisms underlying the genetic predisposition for obesity, eating in the absence of hunger, and difficulty losing or keeping off excess weight.