It tugs at your intestines, which begin to writhe, aching to be fed.

它拉扯著你的腸子，使它們開始扭動，因渴望進食而作痛。

Being hungry generates a powerful, often unpleasant physical sensation that's almost impossible to ignore.

飢餓能帶來一種強烈並且令人不悅的生理感受，這種感覺幾乎難以忽視。

After you've reacted by gorging on your morning pancakes, you start to experience an opposing force, fullness, but how does your body actually know when you're full?

在為了止饑而吞下早餐鬆餅之後你會有全然不同的感受，那就是飽足感，但你的身體是如何知道你已經飽了呢？

The sensation of fullness is set in motion as food moves from your mouth down your esophagus.

當食物進入口腔並往食道移動時，飽足感變開始啟動。

Once it hits your stomach, it gradually fills the space.

一旦食物進到胃部，食物會漸漸地填滿空間

That causes the surrounding muscular wall to stretch, expanding slowly like a balloon.

這會使周圍肌肉壁伸展像一顆氣球一樣慢慢撐開。

A multitude of nerves wrapped intricately around the stomach wall sense the stretching.

密佈胃壁的大量神經感知到肌肉的伸展。

They communicate with the vagus nerve up to the brainstem and hypothalamus, the main parts of the brain that control food intake.

接著透過迷走神經傳送訊息到腦幹和下視丘，這兩部分是腦部主要控制食物攝取的區域。

But that's just one input your brain uses to sense fullness.

但這只是你的腦部感知飽足感的其中一種方法。

After all, if you fill your stomach with water, you won't feel full for long.

畢竟，如果你是灌水灌飽的，很快就會餓了。

Your brain also takes into account chemical messengers in the form of hormones produced by endocrine cells throughout your digestive system.

你的腦同時會接收化學訊息，這些訊息由荷爾蒙組成，是透過位於消化系統的內分泌腺細胞所產生。

These respond to the presence of specific nutrients in your gut and bloodstream, which gradually increase as you digest your food.

這些化學訊息會對你內臟和血管中特定的營養素產生反應，並且，隨著你消化食物越多，訊息量也逐漸增多。

As the hormones seep out, they're swept up by the blood and eventually reach the hypothalamus in the brain.

荷爾蒙滲出後會被血液運送走，最後送達腦部的下視丘。

Over 20 gastrointestinal hormones are involved in moderating our appetites.

二十種以上腸胃分泌的荷爾蒙都和調節食慾有關。

One example is cholecystokinin, which is produced in response to food by cells in the upper small bowel.

其中一種荷爾蒙叫做膽囊收縮素，膽囊收縮素是由位於前段小腸的細胞負責分泌。

When it reaches the hypothalamus, it causes a reduction in the feeling of reward you get when you eat food.

當膽囊收縮素抵達下視丘時，會減少進食所帶來的滿足感。

When that occurs, the sense of being satiated starts to sink in and you stop eating.

這作用開始後，飽足感就開始出現你就不會再繼續吃。

Cholecystokinin also slows down the movement of food from the stomach into the intestines.

另外，膽囊收縮素還能使食物由胃部進到腸子的速度降低。

That makes your stomach stretch more over a period of time, allowing your body to register that you're filling up.

這使你的胃部在一段期間內被撐得更大，讓身體感知到你正開始飽足。

This seems to be why when you eat slowly, you actually feel fuller compared to when you consume your food at lightning speed.

這似乎就是為什麼比起狼吞虎嚥，細嚼慢嚥更能帶來飽足感。

When you eat quickly, your body doesn't have time to recognize the state it's in.

你若是吃得很快，你的身體就會來不及意識到你的飽足程度。

Once nutrients and gastrointestinal hormones are present in the blood, they trigger the pancreas to release insulin.

一旦營養素和腸胃分泌的荷爾蒙進到血液，就會觸發胰臟釋出胰島素。

Insulin stimulates the body’s fat cells to make another hormone called leptin.

胰島素會刺激體內脂肪細胞分泌另一種叫做纖瘦素的荷爾蒙。

Leptin reacts with receptors on neuron populations in the hypothalamus.

纖瘦素和位於下視丘的神經元接收器產生作用。

The hypothalamus has two sets of neurons important for our feeling of hunger.

下視丘有兩組神經元對於飢餓的感知很重要。

One set produces the sensation of hunger by making and releasing certain proteins.

其中一組負責分泌特定的蛋白質引起飢餓感。

The other set inhibits hunger through its own set of compounds.

另一組則是透過它自有一套的化合物來抑制飢餓。

Leptin inhibits the hypothalamus neurons that drive food intake and stimulates the neurons that suppress it.

纖瘦素抑制在下視丘會促進食慾的神經元，並刺激另外那一組會抑制食慾的神經元。

By this point, your body has reached peak fullness.

此時你的身體已經達到飽足。

Through the constant exchange of information between hormones, the vagus nerve, the brainstem, and the different portions of hypothalamus, your brain gets the signal that you've eaten enough.

藉著荷爾蒙、迷走神經、和腦幹以及與下視丘各部位之間的頻繁訊息交流，你的腦部得到你已經吃飽了的信號。

Researchers have discovered that some foods produce more long-lasting fullness than others.

研究者已發現有些種類的食物能帶來更持久的飽足感。

For instance, boiled potatoes are ranked as some of the most hunger-satisfying foods, while croissants are particularly unsatisfying.

舉例來說，水煮馬鈴薯被認為是其中一種最能帶來飽足感的食物，而可頌則是特別難帶來飽足感。

In general, foods with more protein, fiber, and water tend to keep hunger at bay for longer.

大致而言，含有較多蛋白質、纖維和水的食物較可能維持更久的飽足感。

But feeling full won't last forever.

但是不可能永遠覺得飽的。

After a few hours, your gut and brain begin their conversation again.

過了幾小時，你的內臟和大腦會再次開始交換訊息。

Your empty stomach produces other hormones, such as ghrelin, that increase the activity of the hunger-causing nerve cells in the hypothalamus.

你空蕩蕩的胃會分泌其他荷爾蒙，比如類生長素會驅使位於下視丘負責製造飢餓感的神經細胞，使之活躍。

Eventually, the growling beast of hunger is reawakened.

最終飢餓會如一頭甦醒的猛獸咆哮著。

Luckily, there's a dependable antidote for that.

幸好，還有個既可靠又能緩解那隻猛獸的辦法。