Have you noticed when your child eats junk foods like pizza, fried foods, candy, soft drinks, or ice cream, he or she seems to still be hungry? This is a common and alarming trend in kids across America: despite eating a lot of junk food, they still feel hungry. So, why does this happen?
Junk food is considered a source of “empty calories” – meaning it contains little nutritional density. These highly processed food-like substances are often low in fiber, high in sugar and unhealthy fats, and deficient in vitamins and minerals. In comparison, whole foods are higher in protein, fiber, healthy fats, vitamins, and minerals – all of which help balance blood sugar, stabilize energy and mood, and support healthy digestion, concentration, and sleep. Kids (and adults!) feel satiated, or satisfied and full, in part due to the nutrient density of foods. If you’re not eating these important nutrients, then your body may send additional hunger cues since it is lacking essential healthy nutrients to support basic daily functioning, leading to an increase in hunger and overeating.
Dysregulated appetite signals
In addition to lacking necessary nutrients for optimal health, junk food affects the release of chemicals that either increase or decrease hunger. Appetite is controlled by two main hormones that send messages from the stomach to the brain. One of these hormones is ghrelin, which increases hunger; the other is leptin, which decreases hunger. These hormones work together to keep the appetite in balance. Ghrelin is produced in the stomach and increases before meals or when you haven’t eaten for some time. When ghrelin levels are high, kids feel hungry. Unhealthy foods like trans fats, sugars, or overeating stimulate ghrelin production and increase appetite. Leptin is produced in fat cells and tells us we are no longer hungry once we’ve eaten. Leptin sends the opposite signal – when it is high, kids are satisfied. When kid eats healthy whole foods – high in protein, healthy fats, fiber, vitamins, and minerals – this will increase leptin levels and keep hunger at bay.
Overeating & food cravings
Another reason why junk food may increase hunger is the addictive cycle of overeating and activating the brain’s reward system (you can read more about the addictive nature of junk food here). This creates a cycle of cravings and withdrawals. When the brain’s reward system is activated, it increases the desire to eat more, even when you’re not truly hungry.
You can see how this cycle quickly leads to increased hunger and cravings for junk food, fueling a cycle that is difficult to stop.
The good news is appetite will normalize and cravings will decrease when you cut out the junk food and replace it with nutritious meals.