Why do people like eating junk food?

Faced with the temptation of delicious food, dieters often encounter such a problem: Why do desserts and junk food with high fat content always arouse appetite, but those healthy foods (such as vegetables) can't? Ice cream, instant noodles, candy, chocolate, cola, potato chips and French fries are all snacks that primary school students like. Children often ask: Why are all delicious things junk food? Why are nutritious foods (healthy foods) so unpalatable? The British "Daily Mail" gave the answer: Experts believe that these things happen for a reason, and they attribute them to evolution, mental factors and physical needs.

1 What is junk food?

Junk food generally refers to high-calorie food, which is easy to make people fat, but other nutrients are insufficient. The top ten junk foods announced by the World Health Organization include: fried foods, pickled foods, and processed meat foods (dried meat, floss, sausages, ham, etc. ), biscuits (excluding low-temperature baking and graham crackers), soft drinks and cola drinks, convenience foods (mainly instant noodles and puffed foods), canned foods (including fish and fruits), and preserved fruits.

2, like "junk food" is inherited from ancestors.

Why does everyone like to eat junk food with high fat and sugar? It is found that the preference for sweets and high-salt foods is determined by some genes of human beings, and most junk foods are sweet and salty, which can bring people a sense of pleasure. It has been found that human tongues naturally "love" fat. As early as 2005, French scientists published a study on the tongue: the taste buds on the tip of human tongue contain a kind of protein which is particularly sensitive to fat. This protein, named "CD36", is particularly good at "detecting" fatty acids in food and quickly accumulating in the body. In the past, there was a saying among the people that "too much oil does not rot vegetables", which means that cooking with too much oil tastes delicious.

Scientists have explained this phenomenon from the perspective of "evolution". Prehistoric human beings were short of materials and it was difficult to find food. They are busy all day, but it is difficult to make ends meet. Their physical strength is always "beyond their means" and their subcutaneous fat is always "too thin". What they yearn for most is sugar and fat, because only high-calorie food can keep them alive. When we see food, the brain secretes dopamine. Opioid is another chemical secreted by the brain, which will make us feel happy and enjoy. It works with dopamine, and the brain will associate eating a certain food with a happy mood and make us repeat it. They let human ancestors enjoy high-fat and high-sugar foods, and the brain ordered them to look for these foods. So the brain regards eating high-calorie food as a pleasant behavior, instructing people to look for high-fat and high-sugar food. Even today, although the source of food is fully guaranteed, this chemical reaction still exists in the brain, which makes us still like to eat "junk food" containing a lot of oil and sugar.

3. High-calorie food can reduce stress.

It is easy for stressed people to want to eat high-fat and high-sugar food. The researchers found that this practice may indeed help relieve stress, because "junk food" has similar chemical effects on the brain as antidepressants. Researchers at the University of New South Wales, Australia, took two groups of mice as experimental objects. First, they were isolated from the "mouse mother" for a long time, which made them feel anxious and uneasy. One group of mice was fed "junk food", while the other group was fed healthier food. Then the two groups of mice walked through the maze respectively for stress test. The results showed that the mice that ate "junk food" were significantly less anxious than those that ate "healthy food". Scientists believe that "junk food" can help mice replenish stress hormone receptors that are lacking in their brains, thus changing their state.

When people feel stressed, the body will secrete a hormone cortisol, whose primary task is to raise blood sugar level and provide energy for cells, but it will also increase appetite and lead to obesity, prevent the secretion of leptin and insulin, and increase hunger, thus making people want to eat high-calorie food more. American researchers have found that when people see bad news, they not only eat more, but also choose high-calorie foods. It is reported that psychologists at the University of Miami showed people two sets of word cards. One group writes ordinary sentences, and the other group writes negative sentences. Two bowls of food were placed in front of the subjects, one was general food, and the other was high-calorie food, and the calories were clearly marked in the bowls. It was found that people who saw negative narratives not only ate 40% more, but also chose bowls with high calories. The person in charge of this study said that experiments have proved that the factor that attracts people to eat hard is not the smell of food, but the heat. He explained that bad news can make people feel that their survival is threatened and they must hoard more calories.

Eating junk food is addictive.

Why can't we stop when we know that junk food is so harmful? Can junk food be addictive? The Scripps Institute in the United States found that the brains of experimental mice often changed after eating high-calorie and high-fat foods such as sausage, bacon and cheese protein, which was similar to the brain changes of drug-addicted animals such as cocaine and heroin. Laboratory rats addicted to junk food will reject some healthy foods. Research in the Addiction Laboratory of Boston University School of Medicine believes that some substances in the accumulated fat will also change the reward threshold of the brain, thus forming a vicious circle-only by eating more can you get satisfaction. Letting mice get rid of high-calorie food may lead to changes in the brain similar to drug withdrawal and alcohol withdrawal.

5. Why do most "healthy foods" taste bad?

This is because many nutrients have their own special taste, such as insoluble dietary fiber, which helps intestinal peristalsis; Substances that prevent intestinal cancer and constipation are also things that make food rough; Tannin and oxalic acid are powerful antioxidants, which are beneficial to prevent diabetes and hyperlipidemia, and can also make food converge; Glycosides, terpenoids and polyphenols, such as naringin in lemon and grapefruit and tea polyphenols in tea, are all ingredients that help prevent cancer and heart disease, and also make food bitter ... The American Journal of Clinical Nutrition once published an article about the taste of "nutrients", and found that most nutrients have a bitter, astringent or irritating taste. The researchers also asked consumers to evaluate the taste of various foods, and found that the higher the nutritional content, the lower the taste evaluation of foods.