How Junk Food Shapes a Teen’s Developing Brain

Obesity is becoming more common around the world, especially among children and adolescents. More than 150 million children worldwide suffer from obesity in 2019. These children have increased risk of heart disease, cancer and type 2 diabetes.

Teenagers with obesity are will probably remain obese as adults. If these trends continue, 70 percent of adults by the age of 40 by 2040 may be overweight or obese.

I am a neuroscientist and my research is about how diet changes the brain. I want to understand how an unhealthy diet affects the developing brainand why adolescent people today are so susceptible to obesity.

Teenagers are the biggest consumers of high-calorie junk foods. Many children have insatiable appetites during adolescence because rapid growth requires a lot of energy. Increased metabolism and growth spurts may protect against obesity, to some extent. However, excessive consumption of high-calorie junk foods and an increasingly sedentary lifestyle may outweigh any metabolic protection.

The Teenage Brain Is Vulnerable

The teenage years are key window of brain developmentAdolescence coincides with newfound social autonomy and independence in making decisions about food.

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Read more: Your Brain on Sugar: What the Science Really Says

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During adolescence, the connections between different brain areas and individual neurons are also refined and strengthened. The adolescent brain is susceptible to change because increased levels of “neuroplasticity.”

This means that the brain is highly susceptible to being shaped and reprogrammed by the environment—including diet. In turn, these changes can become indefinite once development is complete. The adolescent brain is therefore susceptible to Diet-induced changesbut these changes can last a lifetime.

Resisting junk food is tough

Neurobiologists utilize functional brain imaging to study how the brain responds to certain events. Brain scans show that Prefrontal cortex — a key area of ​​the brain responsible for controlling behavior and decision-making — doesn’t fully mature until the early 20s..

The prefrontal cortex controls and overrides impulses triggered by events in the environment. Resisting the urge to eat an entire bag of candy or buy economical junk can be especially tough for teenagers.

Insatiable desire for rewards

In contrast to the immature prefrontal cortex, the reward system in the brain – this mesocorticolimbic dopamine system — is fully developed at a much younger age.

Teenagers are especially interested in rewards, including sweet and high-calorie foods. This is because increased number of dopamine receptors in the adolescent brain, so the feeling of reward may be exaggerated. Regular stimulation of the reward system causes lasting brain adaptations.

During puberty, these changes can cause long-term brain chemical imbalances.

In total, the adolescent brain has an unbridled need for reward, decreased behavioral control and susceptibility to being shaped by experiences.

This manifests as a decreased ability to resist rewarding behaviors. It’s no wonder that teens prefer to eat foods that are simple to obtain and instantly satisfying, even in the face of health advice to the contrary. But what are the lasting consequences for the brain?

Transcranial magnetic stimulation

Functional imaging studies show brain activity while performing tasks or viewing images of food. Brain circuits that food rewards are more active in adolescents with obesity compared to those whose body weight is considered normal.

Interestingly, lower activity was observed in the regions Prefrontal cortexThis shows that obesity can both boost reward activation and decrease brain activity in centers that may override the desire to eat.

Importantly, effective weight loss in teenagers restores activity level in the prefrontal cortex. This provides key knowledge that the prefrontal cortex is a key brain region for controlling food intakeand that the diet increases activity in areas of the brain responsible for self-control.

Transcranial magnetic stimulation (TMS), a way for scientists to modify brain activity in the prefrontal cortex, may change of braking control eating behavior. Repeated TMS treatment may be a new therapy restore cognitive control over eating, which helps with long-term weight loss.

Exercise increases brain plasticity

Excessive consumption of junk food during adolescence can alter brain development, leading to lasting bad eating habits. However, like a muscle, the brain can be trained to improve willpower.

Greater brain plasticity during adolescence means the adolescent mind may be more susceptible to lifestyle changes. Physical exercise increases brain plasticityhelping to establish up-to-date hearty habits. Identifying how the brain is changed by obesity provides opportunities for identification and intervention.

Functional brain imaging provides a up-to-date level of information that allows doctors to identify people at risk and track brain changes that occur during nutritional and lifestyle interventions.

Moreover, TMS may prove to be a up-to-date therapeutic approach aimed at improving the calibration of the adolescent brain and preventing indefinite changes in adulthood.

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