Does the mere sight of food ignite desire to gorge upon high-calorie meals? This may well be due to low blood sugar levels in your body.
The brain's response to the sight of food appears to be driven more by how low our blood sugar level is at the moment than our upbringing or genetics, says a study.
While genetics and upbringing play a big role in how much we weigh and how much we normally eat, our immediate response to food in the environment is driven by our bodies need for nutrition at the time, said Ellen Schur, an associate professor of medicine at University of Washington.
"The finding suggest our brains have a way to override our genetic inheritance, upbringing and habits to respond to our immediate nutritional needs," Schur added.
For the study, researchers used brain scans to compare how appetite centers in the brains of identical twins responded to images of high- and low-calorie foods.
The researchers enrolled 21 pairs of identical (monozygotic) twins who had been raised together.
The researchers found the twin pairs gave similar responses when asked to rate their appetite before and after meals, had similar hormonal responses, and even ate similar amounts - the findings that suggest these responses were influenced by their shared upbringing and genetics.
Response tended to be greater in the twin with lower blood glucose levels when they were shown photographs of food.
"Just looking at pictures of high-calorie foods when we are hungry strongly engages parts of the brain that motivate us to eat," Schur noted.
The findings might help explain why eating regular meals helps people keep their weight under control, she said.