Why do we overeat?

Why do we eat without feeling hungry? Why do we prefer meat, even though we know how much more reasonable it is to eat fish? Is weak will to blame for everything? No! Our appetite is strongly influenced by factors that we are not aware of.
The disturbed production of hormones in the gastrointestinal tract makes us feel perpetually hungry.

“These hormones, especially ghrelin and leptin, control the mechanisms of satiety and hunger,” explains Prof. Malgozata Kozlowska-Wojcechowska from the Medical University of Warsaw. – Ghrelin, produced in the stomach, signals hunger, which is quickly sent to the brain. In turn, when we sit down at the table, the intestines begin to produce leptin, which tells the brain that the body has received food. Disrupted production of these hormones can make it very difficult for a person to satisfy their hunger. The main culprit for this is gut bacteria, because they play a key role in the mechanisms that regulate our appetite. Some bacteria, particularly the intestinal bacillus, multiply quickly and, as new research from New York University’s Human Microbiome Project shows, can block the satiety signal sent from the gut to the brain.

“If our menu lacks nutrients important for the bacteria, they are “starved” and tend to gluttony,” explains Prof. Kozlovska-Wojchehovska. It turns out that the level of insulin depends on the state of the intestinal microflora. This is another hormone that strongly influences the brain’s ability to control hunger and satiety. “Circulating in the blood, insulin sends a signal to the brain that it is time to eat. – says the professor. – Therefore, it is very difficult for overweight people to control their appetite: their insulin level is often elevated, as a result of which they experience hunger pangs.”

“There are many false beliefs and delusions,

related to nutrition. I often encounter them in my patients who are trying to lose weight, – says Malgozhata Kozlovska-Wojchehovska. “Recently, one of them assured me that he cannot replace fatty meat with fish, because he is not satisfied.” This, of course, is false: although fish is lower in calories than pork, it fills the stomach in the same way, and this signals to the brain that the person is full.”
Very often we come across the position about the beneficial effect of alcohol on digestion. In fact, there is no evidence that it speeds up metabolism and prevents weight gain. Worse, even a small amount of alcohol increases appetite. Psychologists from Glasgow Caledonian University claim that drinking a glass of wine as an aperitif, we eat more than if we had not consumed alcohol. For four days, they observed about twenty men, divided into three groups. The first group each drank half a bottle of wine before lunch, which consisted of French fries and pizza. The second group drank a glass of wine during the meal, the third group drank water during the meal. The scientists then weighed the leftovers on the participants’ plates. It turned out that those who drank a glass of wine before eating ate the most. This Scottish study was conducted with men, but scientists at the Indianapolis College of Medicine soon concluded that the same applies to women. At the same time, it became clear why this is happening. Using functional magnetic resonance imaging, they monitored the participants’ brains. It became clear that those who drank alcohol had a much stronger activation of the brain regions responsible for the sense of aroma during a meal. Because the brain becomes more sensitive to the aroma of dishes.

Nature has come up with several clever ways for us to enjoy sitting down to eat.

First of all, it stimulates our taste, which turns out to be a more complex phenomenon than previously thought. 20 years ago, we were sure that a person could taste four basic tastes: sweet, salty, bitter and sour. Recently, another fifth taste was added to them – “umami” – a Japanese name meaning “appetizing” and expressing the taste of glutamic acid, which is particularly rich in Asian cuisine. New research shows that judging by everything, the tastes are even more: scientists from the American University “Purdue” claim that a person is also able to distinguish the oily taste – “oleogustus”. This is the taste of the fatty acids that make up triglycerides.

“It arises in the process of chewing. By itself, this taste is not very pleasant, but it gives the dishes an attractive, mild taste,” says Prof. Richard Mytes. – To all this we must add the aromas that our nose perceives with its thousands of receptors.

Everything said so far is only the beginning. How tasty food seems to us also depends on visual perception. According to Dana Small, a neuroscientist from Yale University, the appearance of the dish can completely change the taste sensations. In the article published in a popular American medical publication, the researcher tells about an experiment conducted by French scientists from the University of Bordeaux. They added an odorless and tasteless red colorant to the white wine, then offered the drink to be judged by leading sommeliers. It turned out that even experienced experts were wrong: they were describing the taste of red wine, not white wine, even though the two varieties are very different.

Appetite can be provoked by the color of the dishes. Warm colors have the strongest impact: red, yellow, brown. They indicate that the product is ripe, or that the dish is toasted or over-fried. We find green or gray food the least tasty. The utensils we use also play their role. Researchers from the University of Oxford proved that when participants in the experiment used a plastic spoon instead of a metal one, the taste of the yogurt seemed richer and the consistency thicker.

Cheese also changes its taste depending on the utensil with which we bring it to our mouth: knife, fork or spoon. With a knife, it seems sharper and saltier. Does our brain bring up associations related to sharp utensils and connect them to taste sensations? We don’t know that yet. However, it is known that our food preferences are influenced by the types of kitchen utensils. Scientists from the University of Basel prove that the brain reacts negatively if we are served an appetizing dish on a red plate. They conducted two experiments in which they examined the response of college students to drinks and snacks served in red or gray kitchenware. It turned out that participants in the experiment were much less likely to reach for chips and coke served in red dishes than in gray ones. The researchers suggest that this is related to the specific role of the color red: the brain instinctively associates it with danger and struggle.

If we want to curb our appetite, let us eat in silence

To the sounds of music, you can eat a much larger portion, – proves Nanette Strable, a researcher from the University of Georgia, who for seven days carefully monitored the nutrition of 78 students. When their favorite music played during meals, almost everything stayed at the table longer and tended to eat more. If dimmed light was added to this, the effect was even stronger. As proved by scientists from the University of Cornwall, in restaurants with soft light and pleasant music, guests consumed 175 calories more than in brightly lit and noisy places. Appetite is also stimulated by sounds related to the eating process itself.

“The sound we hear when we bite is an element that escapes our notice of the concept of ‘tasty,'” wrote Prof. Charles Spence, an experimental psychologist at Oxford, in his recent publication. He suggests that we love crunchy products the most, which we subconsciously associate with their freshness. This addiction, Spence argues, is related to those times when man ate mainly fruits and vegetables. The first sensations of the dish remain very important to this day: the louder the crunch sounds, the more we want to eat it all and then ask for more.

Moreover, for unknown reasons, it seems to us that crunchy food is less caloric than mushy. A study showing how many people believe this is described in one of the latest issues of a popular medical journal. The authors of the article, researchers from the University of South Florida, conducted a simple experiment. At first, the participants were treated to brownies: softer, with a liquid medium and harder, well toasted. Then they were asked the question: “How many calories do you think are in this dessert?” Most participants in the experiment answered that the soft cake was 55% more caloric than the hard one, even though they had the same calorie content.


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