The Amount Of Gray Matter In Your Brain May Predict If You’ll Stick To Your Diet

It’s hard not to succumb to the temptation of a plate of fries, with its tantalizing smell and beautiful gold color. But whether or not you succumb to this delicious temptation may have something to do with the shape of your brain – and more specifically, how much gray matter you have on it.

A new study published yesterday (June 4) in the journal JNeurosci found that people with more gray matter in two spots in a region of the brain called the prefrontal cortex appear to have more self-control when it comes to making healthier food choices. (Gray matter is where neuronal cell bodies are found in the brain, and therefore where most of the brain’s activity occurs).

Gray matter could be a potential “signature of self-control,” says Hilke Plassmann, a professor of decision neuroscience at INSEAD in France. It can indicate how likely a person is to break their eating habits or reach for a carrot instead of a cupcake.

The prefrontal cortex is located just behind the forehead and is known to be involved in planning and decision-making. In this study, researchers looked at two specific parts of the prefrontal cortex, called the dorsolateral prefrontal cortex and the medial prefrontal cortex of the bra, both of which have been previously associated with self-control, Plassmann told Live Science.

In the first part of the study, the researchers analyzed data from three previous experiments that collected information on the amount of gray matter in the brain. These previous experiments included a total of 91 participants, all of whom were thin and were not dieting.

While the participants were inside the MRI machine, they were given one of three instructions: “Consider the healthfulness of a food,” “Consider the taste of a food,” or “Make a decision naturally.” Five seconds after participants looked at these instructions, an image of a food, such as yogurt or cookies, popped up on the screen and participants had to rate the food on a scale of “strongly disagree” to “strongly agree” based on how much they wanted to eat that food. To reduce the likelihood that the participants would lie, the researchers told the participants that they would get the food they wanted at the end of the experiment. (This was not a lie either, they got the food).

If the participants were more concerned about the healthfulness of a food item or less concerned about how tasty it was, the researchers gave them strong self-control ratings. Brain scans showed that people with more gray matter in both areas of the prefrontal cortex showed greater self-control, the study found.

In the second part of the study, the researchers recruited a whole new group of people to see if the findings on gray matter would still hold true when people were given more leeway in how they controlled their dieting behavior. As with the first experiment, the researchers put a set of instructions in an MRI machine for the participants. This time, however, they switched those instructions, telling participants to “distance themselves” from the food, “indulge” in the food, or “make decisions naturally.” Similarly, participants were shown images of the food and asked how much they would pay to eat that food, ranging from nothing to a scale of $2.50.

The researchers found the same results when they compared the amount of self-control people had with the amount of gray matter. More gray matter seemed to indicate more self-control.

Columbia University psychology professor Kevin Ochsner, who was not involved in the study, said the results were interesting, adding, “I think [the findings] would have been expected, and I think it’s significant.”

The most interesting finding was the involvement of the medial prefrontal cortex of the bra, Ochsner told Live Science.Another region of the prefrontal cortex that the researchers looked at, the dorsolateral prefrontal cortex, would have been expected to be “involved in many forms of explicit, deliberate self-control,” he said. On the other hand, “the medial prefrontal cortex of the bra is generally characterized as an important component of subjective evaluations, such as how idiosyncratic this thing is to me.” In other words, motivation to pursue a diet may be a factor here, he says.

Figuring out “the way these two regions interact could be very important,” Ochsner added, because the study didn’t clarify the relationship between the dorsolateral prefrontal cortex and the bra medial prefrontal cortex and how they work together for dietary self-control.

In future studies, researchers could try to find out if people can train the areas of the brain associated with self-control and thus increase the density of gray matter there. Your “brain is plastic, so your brain structure will change over time,” says Plasman.” I don’t want people to say, ‘I’m just not good at self-control, I can’t change it,'” she adds.

While this specific case hasn’t been tested yet, the brain’s plasticity has been proven before in many studies, many of which have come to the same conclusion. Specific brain regions can change over time, especially the more you exercise them.