Blood sugar levels closely linked to how our brains respond to the sight of food, twin study finds

Our 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, researchers said at the annual meeting of the Society for the Study of Ingestive Behavior. "The finding suggest our brains have a way to override our genetic inheritance, upbringing and habits to respond to our immediate nutritional needs," said Dr. Ellen Schur, associate professor of medicine at the University of Washington.

In the study, Schur and UW Medicine colleagues at Harborview Medical Center, used brain scans to compare how appetite centers in the brains of identical twins responded to images of high- and low-calorie foods. The scans, called functional magnetic resonance imagers (fMRI), detect differences in the activity in different brain centers by measuring changes in

Studies of identical twins have shown that genetics and upbringing play a major role in a person's body weight regulation. In this study, the researchers wanted to determine what role inherited similarities in brain function had on appetite. In the study, the researchers hypothesized that because have nearly identical genetic inheritance their brain appetite centers would react similarly when the twins were shown the images of high- and low-calorie foods. To test their hypothesis, the researchers enrolled 21 pairs of identical (monozygotic) twins who had been raised together. The twins were first fed a standardized breakfast, and 3.5 hours later they underwent a baseline fMRI brain scan.

After the first scan, they were fed a filling meal of macaroni and cheese, calibrated to satiate their appetites. The twins then had a second fMRI during which they were shown photographs of non-fattening foods, such as fruits and vegetables, and fattening foods, such as pizza and french fries.

Changes in blood flow measured by the fMRI were used to assess how the activity of key appetite-regulating centers in their brains changed in response to the images. Afterwards, the twins were offered to eat what they would like from a buffet. How much they ate from the buffet was recorded.

At regular intervals during the experiment the twins were asked to rate their feelings of hunger, fullness and satisfaction, using a standardized scale, and blood samples were taken to measure and levels of regulatory hormones, such as insulin, leptin and ghrelin.

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 from the buffet—findings that suggest these responses were influenced by their shared upbringing and genetics. That did not seem to be the case with brain activation in response to the food images, however, when response tended to be greater in the twin with lower blood glucose levels.

The findings suggest that 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, Schur said. "Just looking at pictures of high-calorie foods when we are hungry strongly engages parts of the brain that motivate us to eat." The study's findings might help explain why eating regular meals helps people keep their weight under control, she said.

Provided by Society for the Study of Ingestive Behavior

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Twins talk half as much at two

Jun 04, 2014

(Medical Xpress)—A world first study of language development in toddler twins confirms the widely held belief that twins start to talk later than single-born children.

Simple gut hormone combo makes our brains think we're full

Oct 25, 2011

Many of us would love nothing more than to trick ourselves into believing we are full even as our stomachs remain empty. Now, a new brain imaging study reported in the November issue of the Cell Press journal Cell Metabolism sugges ...

Recommended for you

Organovo has 3D-printed liver tissue for drug testing

Nov 20, 2014

(Medical Xpress)—The commercial release of 3D printed liver tissue was announced earlier this week. Organovo is the company behind the release. The product is intended for use for preclinical drug discovery ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

JVK
not rated yet Jul 31, 2014
Excerpt: "The findings suggest that 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, Schur said."

Why doesn't anyone say, we're all just like Pavlov's dog? It seems obvious that our response to the visual appeal of food is hormone-organized, hormone-activated, experience-dependent, nutrient-dependent and classically conditioned.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.