Brains of Obese Children Respond more to Sugar

When they are tasting sugar, obese children get more of a kick from it. New research has found that their brains literally light up differently.

These children are experiencing a more intense sense of food reward. Food reward involves being motivated by food and deriving a good feeling from it.

Some children may have brain wiring that predispose them to crave more sugar throughout life, the researchers say.

The study does not prove a causal link between sugar hypersensitivity and overeating. It does, however, support thoughts that the increasing number of America’s obese youth may have a heightened psychological reward response to food.

“The take-home message is that obese children, compared to healthy weight children, have enhanced responses in their brain to sugar,” said first author Kerri Boutelle, PhD, University of California, San Diego School of Medicine professor. “That we can detect these brain differences in children as young as eight years old is the most remarkable and clinically significant part of the study,” she said.

Just a Spoonful of Sugar

The study involved 23 children, ranging in age from 8 to 12. Boutelle and her team scanned the brains of the children while they tasted one-fifth of a teaspoon of water mixed with table sugar. The children were asked to swirl the sugar-water mix in the mouth with their eyes closed, while focusing on its taste.

Ten of the children were obese and 13 had healthy weights, as classified by their body mass indices.

All participants were pre-screened for factors that could confound the results. For instance, they were all right-handed and none suffered from psychiatric disorders, such as anxiety or ADHD. They also all liked the taste of sucrose.

Food Reward Circuitry

The brain scan images revealed that obese children had heightened activity in the insular cortex and amygdala. These areas of the brain are involved in perception, taste, emotion, awareness, motivation and reward.

Remarkably, the obese children showed no heightened neuronal activity in a third area of the brain, the striatum, also part of the response-reward circuitry. Activity of the striatum has, in other studies, been associated with obesity in adults.

But the striatum does not develop fully until adolescence. The researchers said one of the fascinating points of the study is that the brain scans may be showing, for the first time, the early development of the food reward circuitry in pre-adolescents.

“Any obesity expert will tell you that losing weight is hard and that the battle has to be won on the prevention side,” said Boutelle. “The study is a wake-up call that prevention has to start very early because some children may be born with a hypersensitivity to food rewards or they may be able to learn a relationship between food and feeling better faster than other children."

About one in three children in the U.S. is currently overweight or obese. According to studies, children who are obese have an 80 to 90 percent chance of growing up to become obese adults.

K Boutelle, C E Wierenga, A Bischoff-Grethe, A J Melrose, E Grenesko-Stevens, M P Paulus, W H Kaye.
Increased brain response to appetitive tastes in the insula and amygdala in obese compared to healthy weight children when sated.
International Journal of Obesity, 2014; DOI: 10.1038/ijo.2014.206