One piece, two pieces, three or four pieces, five, six, seven, eight or ninety pieces... Is this Zheng Banqiao 's " Yongxue "? No, you are eating potato chips. The appetite in the middle of the night seems to have magic, making people unable to control themselves, and one mouthful after another... We always find various suitable time and excuses for all kinds of sudden appetites. Why do you still want to eat even though you are not hungry? What is the matter with this little goblin who is so irritating about the appetite? Who is the brain, intestines, and cook controlling our appetite?
1. What is appetite?
Appetite is about "wanting to eat". The idea of whether to eat or not comes from the brain. In the brain, there are two types of neurons, , , which is particularly important for controlling appetite. They are , pro-corticotin (POMC) neurons, , and sting mouse-related peptide (AgRP)/neuropeptide Y (NPY) neurons, referred to as AgRP neurons, . POMC neurons and AgRP neurons are two intertwined and communicated neurons, which have opposite effects in appetite control. Among them, POMC neurons promote satiety , while AgRP neurons promote hunger . They interact to form a switching system that can adjust appetite in a timely and quickly. As a system that directly contacts and digests food, can sense changes in nutrient levels in the digestive system, thereby releasing various intestinal hormones into the blood circulation, changing neuronal activity , and then regulating appetite. But which hormone is released depends on the number and type of calories consumed, as well as the presence or absence of various nutrients [1][2].
2. Classification of intestinal hormones
Gerlin (Gherlin) is a protein peptide produced by intestinal endocrine cells. As its name suggests, it is the only intestinal hormone known to promote appetite . Ghrelin activates AgRP neurons by directly and is mediated by AgRP neurons. indirectly inhibits POMC neuron activity , thereby promoting appetite. In addition, ghrein can also affect the neural response of reward pathway -related brain regions to high-calorie foods or their images, and increase the desire for eating by enhancing the reward pathway for food signals.
Cholecystosis (CCK) secretion level in the intestine is proportional to the lipid and protein content in the diet, and is in response to the uptake of saturated fatty acids, long-chain fatty acids, amino acids and short peptide . That is to say, when the intestine senses that this type of nutrient is fully absorbed, CCK will be released. CCK activates POMC neurons by binding to CCK1 receptor , thereby inhibiting appetite and reducing meal volume.
polypeptide YY (PYY) is a peptide chain that stimulates satiety and calorie consumption. PYY activates POMC neurons , while inhibits NPY in AgRP neurons , thereby inhibits appetite and reduces food intake.
glucagon-like peptide-1 (GLP-1) is also a hormone mainly secreted by the intestine. After eating, the intestine releases CCK, GLP-1 and PYY by sensing the ingestion of lipids and protein in the food. GLP-1 activates POMC neurons through the GLP-1 receptor on the surface of the neuron to reduce appetite , reduce food intake and increase fullness. Generally, the increased levels of GLP-1 are proportional to the calories intake.
These hormones in the intestine pass through the brain and intestinal axis, affecting our judgment of hunger and fullness, thus affecting our appetite.So why do I sometimes want to eat more and more, even if I’m full in a meal, but when I see desserts and snacks, I feel like I have another stomach? Why do I sometimes feel so tired of eating so much food that I can’t eat in an instant? This is mainly related to the dishes on the cook. Different foods of or foods composed of different nutrients will affect our appetite .
3. Effect of nutrients on appetite
Compared with carbohydrate , a high-protein diet or high-amino acid diet will make the feeling of fullness faster. Because the presence of arginine , lysine , and glutamate can enhance the satiety of proteins, and some studies have found that the principle of leucine in food suppressing appetite through the brain and intestinal axis is different from other amino acids. It can send a signal similar to "Don't eat, our protein is enough" to indirectly suppress appetite.
After carbohydrates are intake, the intestine secretes less CCK, and the rate of satiety is not as fast as proteins. However, after carbohydrates are intake, the intestine produces less GLP-1 and PYY, so the time for appetite suppression is shorter. Carbohydrates can be mainly divided into digestible refined carbohydrates and difficult-to-digest coarse grains. Among them, the easily digestible refined carbohydrates will also greatly affect blood sugar levels and thus regulate appetite. For indigestible carbohydrates, they ferment in the intestines produce short-chain fatty acid , which helps maintain a healthy working state of the brain and intestinal axis. Like protein and carbohydrate intake, fat intake causes secretion of CCK, GLP-1 and PYY. However, long-term high fat intake will affect the secretion of CCK and GLP-1 and reduce the feeling of fullness. On the contrary, high fat intake increases PYY secretion and effects [1].
So can we fight appetite by regulating the secretion of hormones?
The latest research at present points out that GLP-1 plays an important role in appetite and blood sugar balance . The US FDA approved GLP-1 for the treatment of obesity and type II diabetes [3]. So what magic does GLP-1 have against appetite? Researchers believe that if can continuously stimulate the secretion of endogenous GLP-1 of , it can suppress appetite.
They envision targeting the delivery of nutrients to the colon to stimulate the secretion of GLP-1. It is not easy to place nutrients in a fixed location. Many factors such as acidic pH in the stomach, intestinal permeability, enzymes, microbiota-mediated metabolism and liquid volume need to be overcome. Therefore, the researchers hope to use a pH-sensitive coating to take advantage of pH differences in the intestines to allow the drugs that stimulate GLP-1 release to work in a fixed position. In addition, it can be combined with the time-dependent dosing system to release the drug in a fixed position based on the duration of the digestive tract, such as the drug coating that will not be exposed after 3-4 hours of use. In addition, the researchers also discussed the effects of intestinal bacterial flora and digestive enzyme on drug carriers based on the gastrointestinal mucosal adhesion characteristics. However, these research on the precise delivery of nutrients is still in progress, and we look forward to scientists continuing to reveal the secrets for us.
The method of using GLP-1 hormone to suppress appetite is still in the research stage, and it is not the general public. So what should I do if my appetite is unsatisfactory?
4. Good ideas to control appetite
◆ A smaller plate, decorate less food.
Studies have found that using large tableware will not only make people eat more without realizing it, but will also give people the illusion of insufficient food [4]; when freely adding rice is allowed, the less food is served on the plate at a time, the less people will eat. Therefore, if you want to control your appetite, the plate and bowl of rice should be small, and only the appropriate amount should be served at a time.
◆ Eat slowly and taste carefully.
By chewing more, it can help digestion, reduce gastrointestinal burden, and improve satiety. The gastrointestinal tract can secrete hormones related to appetite. Increased blood sugar can bring signals to the brain to fullness.If you eat too fast, the food cannot be fully absorbed, and the brain cannot get the signal of fullness in time. When you feel that your stomach is full, your energy intake is often too high, which is not conducive to controlling your food.
◆ Watch less food broadcasts and do your meals seriously.
Many people who lose weight often "look at the plum blossoms to quench their thirst" by watching videos. But studies have shown that watching food broadcasts may make you fatter and fatter [5]. The stimulation of food to the human body's vision, taste and smell will cause an increase in the release of inflammatory factors in the brain. However, stimulation caused by eating or browsing food pictures can easily lead to excessive release of inflammatory factors. The inhibition of "insulin release in the first phase" and causes severe inflammatory responses, slowing down the output of insulin , making weight regulation more difficult.
If none of the above tricks can satisfy you, then you might as well take a look at these magical weight loss methods, which may be effective!
◆ The environment is wrong, and I eat a lot.
Studies have found that reducing the contrast between tableware and its background arrangement (table cloth, etc.) can reduce the total food intake by up to 10% [6]. Therefore, try to buy sets of tableware and tablecloths. Not only is the combination beautiful, but you can also eat less without realizing it.
◆ The bacteria are incorrect and it is easy to get fat.
Why do thin people eat too much and not fat? That is intestinal bacterial flora that is causing trouble . In 2006, Professor Turnbaugh first transplanted the cecum flora of lean and fat mice into normal mice. Only 2 weeks later, the people who were transplanted with obese mice grew more fat. For further study, the research group induced obesity mouse model through a Western diet and found that the intestines of mice that were induced by obesity produced a bacteria of the Firmicutes, a spore-producing bacteria; after dietary control of body weight, this type of bacteria was significantly reduced [7]. Therefore, if you want to successfully lose weight, transplanting a little "leptic bacteria" may be useful.
◆ If you play the game well, you can get thinner.
How to easily restrain appetite? Psychologists from Exeter University and Cardiff University gave a special answer - let them play a small game. Experiments have found that this mini game designed for dietary behavior training can help overweight subjects reduce their daily energy intake by about 220 kcal. The secret of this game is that the pictures that appear at the same time as the black box representing stops are some high-calorie, "unhealthy" snacks, such as sweet cakes, potato chips, etc. Through this game training, people associate unhealthy food with "stop" and "rejection" [8], and naturally, they don't want to eat these foods.
Generally speaking, appetite is not a disaster. We can control our energy intake because of appetite. This is a steady-state regulation of the human body. Behind the appetite is not completely "greed", but the presentation of the combined effects of various factors such as the brain and intestinal axis, dietary structure, and living environment.
References
1. Am J Lifestyle Med. 2017;13(6):586-601.
2. J Obes Metab Syndr. 2022;31(2):161-168.
3. Mol Nutr Food Res. 2022;e2200192.
4. FASEB j. 2006;20(4).
5. Cell Metab. 2022;34(7):991-1003.e6.
6. J Consum Res. 2012;39(2):215-228.
7. Nature. 2006;444(7122):1027-1031.
8. Appetite. 2015;95:17-28.
|This article is originally edited by the content team of Tongcheng Beijian Nutrition and Health Research Institute
This article aims to introduce the progress of nutrition and health research, and is not a treatment plan recommendation. If you need treatment plan guidance, please go to a regular hospital for treatment. If you like this content, please forward it. For more health information, please follow "Xiaotang Nutrition Research Institute".
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