Why do people like junk food?
Faced with the temptation of delicious food, dieters often wonder: why do desserts and high-fat junk food always whet the appetite? But healthy foods like lettuce, kale, or apples don't have the same effect? Some say it's a matter of personal preference. In Western idioms, a person who loves sweets is said to have a "sweet tooth," and one who loves savory foods has a "salty tooth." Many also believe that the craving for a certain food is a signal from the body. For example, if you're craving fried chicken, it's because your body needs it. But is that really the case?
The Evolution of Appetite
Appetite can arise from many reasons. Scientists believe it's related to evolution, psychological factors (stress, sadness, etc.), and a genuine need for food. "People need to understand that the desire for food is not simply caused by hunger," explains Andrew Hill, a professor of psychology and behavioral science at the University of Leeds.
Nutritionists believe that hunger is the body's way of ensuring it gets an energy refill. When the stomach is empty, it releases ghrelin, a hormone that communicates with the brain's command center, the hypothalamus. This is how people feel hungry and know when to eat. Satiety is also a bodily signal, triggered by leptin from fat cells and insulin from the pancreas, which tells the body that blood sugar levels have risen.The difference is that the emergence of appetite is more complex. Theoretically, a hungry person will eat any food for survival, even if it's not a preferred type. Appetite, however, is a strong sensory desire for a specific food. In the brain, a series of chemicals are related to appetite.
First is dopamine. When a person has a novel experience, the brain secretes dopamine. Dopamine works with another substance in the brain, opioid peptides, to produce a feeling of pleasure. If certain behaviors can cause the brain to secrete dopamine and opioid peptides, the brain will make the body repeat these behaviors.From an evolutionary perspective, the human desire for junk food can be traced back to prehistoric times. High-calorie foods provided more energy, increasing the survival chances of those who consumed them. As a result, the brain came to see the intake of high-calorie foods as a pleasurable act, directing people to seek out high-fat, high-sugar foods. In the modern era, although food sources are abundant, the human brain still repeats the same chemical reactions. This is why junk food always triggers such a strong appetite.
The Role of Emotions
Emotions are another factor that contributes to the desire for junk food. For example, when stressed, the body releases cortisol. The basic function of cortisol is to increase blood sugar levels to provide energy for cells, suppress the immune system, and promote the metabolism of fat, protein, and carbohydrates. Cortisol also suppresses leptin and insulin secretion, thereby enhancing hunger.
Besides stress, other negative emotions can also lead to cravings for junk food. As children, parents often used candy as a reward and a token of love. When these children grow up, they subconsciously still see high-sugar, high-fat foods as a reward. The enjoyment of taste can also make the brain feel pleasure. For example, sweets can cause the brain to release opioid peptides, which can alleviate pain.What Appetite Should Not Be Ignored
Signals Contained in Appetite
Chocolate and Desserts
Cravings for these foods usually stem from psychological needs. They can make you feel good in a short amount of time.
Pizza, Pasta, or Biscuits
These are all foods made from wheat. If you have a strong craving for them, it might be due to an intolerance to wheat components. Because the body's absorption of these components is insufficient, there is a desire to eat more pasta. This is interesting, similar to diabetes: a patient's body cannot regulate blood sugar, causing an energy deficit, which leads to a craving for sugar.
Fish
If you're particularly craving fish, like salmon, you might be lacking Omega-3 fatty acids. If it's tuna, you might be low on salt. This is common among dieters who consume a lot of low-protein foods like fruits and vegetables.
Dairy Products
Dairy products contain important nutrients that the body needs. If you're really craving cheese, you might be lacking vitamins A and D, especially if your fat intake is insufficient.
Red Meat
This could be a lack of protein or insufficient iron intake, which is common in pregnant women.