Junk food, or so-called “empty-calorie food,” most often includes fast food (such as pizza, hamburgers, fried chicken and French fries) and unhealthy snacks (chips, flavored corn snacks, wafers, packaged cakes and pastries). Junk food has several common characteristics: it is highly processed, low in essential nutrients such as vitamins, minerals, and antioxidants, and rich in so-called “empty calories.” Junk food contains large amounts of added sugar, unhealthy fats, and salt, and very little high-quality protein, fiber, vitamins, and minerals.
Junk Food in the Diet of Children and Adolescents
It is important to highlight, on the one hand, that some fast-food products, although they contain protein, often provide protein of low quality and/or are accompanied by large amounts of fats and additives, which reduce their nutritional value. At the same time, even if they contain certain vitamins or minerals, their amounts are insignificant compared to daily requirements and do not justify the high number of calories consumed to obtain those nutrients.
On the other hand, there are foods commonly associated with the idea of junk food that can actually be a valuable source of nutrients. Pizza is a relevant example. When prepared at home, using whole-grain flour, plenty of fresh vegetables, and high-quality protein sources or cheeses with a moderate fat content, pizza can represent a balanced meal, rich in both micro- and macronutrients.
Contents
The Impact of a Junk Food Diet During Adolescence
Effects on Children’s Health
Does Excessive Junk Food Consumption Lead to Addiction?
The Impact of a Junk Food Diet During Adolescence
Adolescence is a period marked by physical, emotional, and social development and is characterized by significant neurobiological changes in the brain, especially in regions responsible for cognitive control and reward processing. Recent studies have highlighted the negative impact of junk food on brain function in this age group.
The increased neuroplasticity specific to this period may make the brain more vulnerable to the harmful effects of such foods on cognition and behavior.
When we do something that gives us pleasure, such as eating chocolate, a neurotransmitter called dopamine is released in the brain. This reinforces the behavior that produced the pleasure and makes us more likely to repeat the action in order to experience the same pleasant feeling. Dopamine is involved in the brain’s reward system, a complex neural network responsible for the pleasurable sensations associated with certain actions or behaviors. This reward system can become dysregulated, leading to impulsive behaviors and addiction.
From a scientific perspective, adolescents’ susceptibility to impulsive, reward-seeking behaviors, including excessive consumption of high-calorie foods rich in sugars and fats (junk food), can be explained by several factors:
Neuroplasticity, or brain plasticity, refers to the brain’s ability to form and reorganize synaptic connections in response to environmental experiences. While this creates great openness to learning and adaptation, it also increases vulnerability to the harmful influence of unbalanced diets.
The prefrontal cortex, responsible for executive functions such as decision-making, self-control, and planning, is still developing. At the same time, the mesolimbic dopaminergic system, involved in reward processing, is hyperactive. This mismatch in development contributes to adolescents’ tendency toward impulsive behavior and a preference for immediate rewards.
Data from the REBOST study indicate that junk food consumption desensitizes the brain’s reward system to food-related rewards. This means that increasingly larger rewards are required to achieve the same pleasurable effect, and these effects are not immediately reversed by giving up junk food.
At young ages, children and adolescents can develop this tolerance more quickly, meaning they need larger portions or more highly concentrated foods to achieve the same level of satisfaction. Over time, this favors the development of compulsive eating behaviors, such as binge eating.
It should also be noted that obese adults consume more fast food and junk food compared to individuals with a normal body weight. Entering this vicious cycle at a young age increases the risk that excessive junk food consumption will lead to neurobiological changes that increase appetite and compulsive behaviors, thereby supporting the early onset of obesity and its long-term persistence, along with all associated health risks.
Effects on Children’s Health
Regular, long-term consumption of junk food leads to the development of health problems such as obesity and chronic diseases, as well as psychological issues, including low self-esteem, anxiety, and depression.
Deficiencies in vitamin A, vitamin C, magnesium, and calcium promote the development of deficiency-related conditions such as iron-deficiency anemia and osteoporosis later in life. In addition, excessive junk food consumption has been associated with:
Increased risk of atopic disorders such as asthma, eczema, and allergic rhinitis
Constipation, partly caused by reduced intake of fruits, vegetables, fiber, and milk in favor of ultra-processed foods
Addiction: excessive junk food consumption in childhood reduces the likelihood of a healthy lifestyle in adulthood; the taste preference for junk food diminishes children’s appetite for natural, healthy foods, negatively affecting the adoption of balanced eating habits
Sleep disorders
Hyperactivity
Depression
Does Excessive Junk Food Consumption Lead to Addiction?
Several studies have explored the link between junk food and addiction, how junk food addiction develops, and the mechanisms through which people become dependent on unhealthy foods. Specifically:
The combination of sugar, salt, and fat, along with chemical additives found in junk food, has a powerful effect on the brain’s reward centers. Junk food products can cause significant changes in brain activity and function by activating reward centers and affecting neurotransmitters such as dopamine, in a manner similar to what is observed in substance addiction.
Just as in substance addiction, where individuals need to consume substances more frequently and in increasing amounts, food addiction also involves the development of tolerance over time, accompanied by the need to consume larger quantities to achieve the same effect.
