Can't curb your enthusiasm for food? Blame the brain

Next time you give in to that craving for a chocolate bar as your energy levels take a mid-afternoon dip, you could be justified in saying that your brain made you do it.

A new study published in the May 1 issue of the journal Science concluded there are differences in the brains of people who are good at controlling their urges versus those who find it almost impossible.

The researchers found that while everyone uses the same part of the brain to make value-laden decisions like should I eat that candy bar or stick to my diet there's a second region of the brain that can put the brakes on the activity of the first region in people with good self-control.

The activity of the second region allows people to take into account more abstract factors like health in addition to basic desires like taste, the researchers say. That helps them make better overall choices.

The research was conducted by scientists at the California Institute of Technology. The study involved dieters, but the scientists say their findings could also be applied to addictions, illegal behaviour and risky financial decisions since each involves willpower.

Study looked at dieters

In the study, a group of self-reported dieters were shown pictures of 50 foods everything fromchocolate bars to Jello to cauliflower. The participants were asked to rate each food according to how good they thought the food would taste. They were shown the slides again and asked to rate the foods on their health benefits.

The data allowed the researchers to select an "index food" for each volunteer. That was a food that placed in the middle of the pack in terms of taste and supposed health benefits.

Each participant was then shown the 50 foods one more time and was asked to choose between it and the "index item."

Each study volunteer was inside anmagnetic resonance imagingscanner for each of the viewings so the researchers could measure activity in specific areas of the brain.

The researchers identified 19 participants who showed significant dietary self-control by picking mostly healthy food. Another 18 showed very little self-control by picking mostly food they believed to be tastier, regardless of the nutritional value.

The brain scans showed significant differences in the brain activity of the group that showed self-control as compared to the group that preferred taste.

Other studies have shown that value-based decisions like what kind of food to eat are linked to a part of the brain called the ventromedial prefrontal cortex, or vmPFC. If you're looking at food and activity in that part of the brain goes up, it means you are more likely to choose to eat it, says Todd Hare, the lead author of the study.

'We rarely got people to say they'd eat cauliflower if they didn't like cauliflower' Todd Hare

A second area of the brain the dorsolateral prefrontal cortex, or DLPFC became active in study participants with good self-control as they took into account other factors besides taste, like health benefits.

However, Hare notes the DLPFC can only do so much. It can't make you eat something you don't like no matter how healthy.

"We rarely got people to say they'd eat cauliflower if they didn't like cauliflower," Hare said in a news release. "But they would choose not to eat ice cream or candy bars, knowing they could eat the healthier index food instead."

Findings mirror other studies

A recent study by researchers at York University in Toronto found that binge eating might bea factor ofyour genes.

The researchers looked at two groups of obese people: one that suffered from binge eating disorder and a second group that did not.

The researchers found that binge eaters have a specific type of brain receptor one that is also linked with drug and alcohol addiction. It predisposed them to be more responsive to the tastes of sweet and fatty foods.

Scientists believe dopamine fosters our "wanting" of food while opioids regulate the pleasure we get from eating. Previous research on animals found that opioids are linked to binge eating of fat. The York University study took that a step further: it found the same link in humans as well as a different genetic make-up in the opioid receptors of binge eaters than in those who don't binge.

'It doesn't make sense to consider obese individuals as one unified group, as there are many different routes to obesity' Caroline Davis

Lead author Caroline Davis, professor of kinesiology in York's Faculty of Health, says while the study should help improve treatment for people suffering from binge eating disorder, it could also help reshape the way researchers study obesity and weight gain.

Davis says studies normally compare obese people to the non-obese in order to try to understand the causes of weight gain. She says it doesn't make sense to consider obese individuals as one unified group, as there are many different routes to obesity.

The study, "Dopamine for 'Wanting' and Opioids for 'Liking': A Comparison of Obese Adults With and Without Binge Eating," will be published in a forthcoming issue of the journal Obesity.

Remembrance of fat past?

Do you find yourself craving a greasy burger every once in a while just like the one you had on a family road trip when you were a kid? There's a reason: it's etched into your brain, according to another study.

The study, published April 27 online in the Proceedings of the National Academy of Sciences, found that when we eat fat-rich foods, our brains form long-term memories of the experience.

Researchers from the University of California at Irvine found that oleic acids from fats are transformed into a compound called oleoylethanolamide (OEA) in the upper region of the small intestine. The compound sends hunger-curbing messages to the brain to increase feelings of fullness. Elevated levels of OEA can reduce appetite. Lowered levels can do the opposite.

Daniele Piomelli, a co-author of the study, says OEA's memory-enhancing ability might have helped early humans survives, but things are different today. People now expend very little energy acquiring fatty foods. So the brain's ability to remember can cause cravings that lead to excess consumption and obesity.