你是否有過(guò)這樣“甜蜜的煩惱”呢？

“明明剛吃完火鍋，看到提拉米蘇卻還能再戰(zhàn)三百回合”。據(jù)說(shuō)每個(gè)人都有兩個(gè)“胃”，一個(gè)用來(lái)吃飯，一個(gè)用來(lái)吃甜點(diǎn)。無(wú)論吃得有多撐，永遠(yuǎn)有甜點(diǎn)的一席之地。

Have you ever pondered the phenomenon of consistently finding room for dessert when the dessert menu is presented? Researchers may have unraveled this mystery. The researchers at the Max Planck Institute for Biology of Ageing have discovered that the nerve cells responsible for inducing satiety post-meal also play a role in triggering sweet cravings following a meal.

大腦對(duì)甜食很“雙標(biāo)”

科學(xué)家們發(fā)現(xiàn)：人類對(duì)甜食的執(zhí)念，竟是源于神經(jīng)系統(tǒng)的“雙重欺騙”。大腦中本該抑制食欲的關(guān)鍵神經(jīng)元，在面對(duì)甜食時(shí)，卻會(huì)刺激食欲，告訴大腦“我還能吃”。

德國(guó)馬克斯·普朗克代謝研究所科研團(tuán)隊(duì)稱，我們的POMC神經(jīng)元具有“雙重身份”。通常在我們吃飽喝足時(shí)，下丘腦中抑制食欲的神經(jīng)元——POMC神經(jīng)元，會(huì)被激活并發(fā)出“停止進(jìn)食”的信號(hào)，就像在對(duì)身體說(shuō)“別再吃了”。而即使吃飽了，在甜食面前，POMC神經(jīng)元卻會(huì)“背叛”身體，一反常態(tài)，改為促進(jìn)釋放β-內(nèi)啡肽刺激進(jìn)食欲望。

A report describes "a subset of neurons located in the hypothalamus—a deep brain region—that typically signal to us to stop eating post-meal. These neurons were found to drive sugar consumption in mice even post-satiation." Through brain imaging, researchers observed similar mechanisms in humans.

北京大學(xué)人民醫(yī)院劉健教授解釋：“β-內(nèi)啡肽與大腦的獎(jiǎng)勵(lì)中心相互作用，制造愉悅記憶，讓我們?cè)诔蕴鹗硶r(shí)覺(jué)得又開(kāi)心又滿足。這本質(zhì)上是一種進(jìn)化機(jī)制——在食物匱乏時(shí)期，促使人類優(yōu)先獲取高熱量資源。”

甜食會(huì)改變我們的大腦

發(fā)表在《細(xì)胞代謝》期刊上的一項(xiàng)研究顯示：高脂肪和高糖食物會(huì)改變我們的大腦。如果經(jīng)常吃，即便是少量食用，未來(lái)大腦也會(huì)精準(zhǔn)地提醒人們?cè)俅问秤眠@些高糖高脂食物。研究人員解釋：當(dāng)人們天天食用高糖高脂食物后，大腦會(huì)建立連接，下意識(shí)地偏愛(ài)這些食物，更喜歡選擇高脂高糖的食物。

Sugar overconsumption is one of the main drivers of poor health conditions such as obesity, Type 2 diabetes and cardiovascular disease. "What we choose to eat is controlled by our brain, but not all foods are equally 'rewarding' for the brain."

對(duì)甜食的偏愛(ài)“經(jīng)久不衰”，和腸道神經(jīng)也有關(guān)。 研究發(fā)現(xiàn)，一旦甜食進(jìn)入胃腸道，腸腦軸就會(huì)被激活。腸腦軸是指腸道和大腦之間通過(guò)神經(jīng)、內(nèi)分泌和免疫等多種機(jī)制形成的雙向交流系統(tǒng)，不僅調(diào)節(jié)著機(jī)體的消化、吸收、代謝等生理功能，還深刻影響著情緒、認(rèn)知、行為等心理過(guò)程。腸道神經(jīng)受到刺激，大腦隨之釋放攝入更多糖的信號(hào)，使“甜食偏好”持續(xù)存在。

如何科學(xué)有效克制“糖癮”

《中國(guó)居民膳食指南(2022)》推薦，糖攝入量每天不超過(guò)50克，最好控制在25克以內(nèi)。控制“糖癮”，最好從以下5件事入手。

▌增加膳食纖維攝入

血糖波動(dòng)正是引發(fā)糖癮的元兇，而我們可以通過(guò)提高膳食纖維攝入來(lái)預(yù)防血糖驟升。常見(jiàn)的高膳食纖維食物有洋蔥、大蒜、蘆筍、蘋(píng)果等。這些食物中的益生元纖維可通過(guò)改變腸道菌群直接影響大腦神經(jīng)活動(dòng)，使人體對(duì)甜食的渴望降低。

Research has also found that eating prebiotic fibre, found in foods like onions, garlic, asparagus and apples, causes changes in the gut bacteria that directly affect the brain, making you less likely to crave sugary foods. Switch to wholegrain bread, rice and pasta and leave the skins on potatoes for an immediate fibre boost.

▌足量攝入優(yōu)質(zhì)脂肪與蛋白質(zhì)

每餐需確保優(yōu)質(zhì)脂肪與蛋白質(zhì)的足量攝入。這兩類營(yíng)養(yǎng)素能在餐后顯著延長(zhǎng)飽腹時(shí)間、增加飽腹感，將對(duì)于飯后甜點(diǎn)的渴望降低。

Healthy fats, in the form of full-fat dairy, nuts, avocados and olive oil, and protein in nuts, eggs, fish and beans, are important in determining how satisfied you feel, so try to include them in every meal.

▌優(yōu)先選用純天然未加工的食物

超加工食品的成癮性已獲科學(xué)驗(yàn)證——食品制造商通過(guò)精確調(diào)控“糖-鹽-脂肪”的黃金比例，刻意激活大腦愉悅中樞，這種令人欲罷不能的配比被稱為“極樂(lè)點(diǎn)”（the bliss point）。研究表明，持續(xù)攝入超加工食品會(huì)使大腦獎(jiǎng)賞系統(tǒng)敏感度降低，導(dǎo)致對(duì)天然甜味的感知閾值不斷提高。

▌建立“正念飲食觀”

營(yíng)養(yǎng)師指出，大部分的甜食渴求實(shí)為情緒性進(jìn)食。當(dāng)人體處于壓力狀態(tài)時(shí)，皮質(zhì)醇水平升高會(huì)觸發(fā)對(duì)快速能量的需求，這種生理機(jī)制往往被誤判為饑餓感。值得注意的是，情緒化攝入甜食后，有部分個(gè)體會(huì)產(chǎn)生自責(zé)情緒，反而加劇心理壓力。

Try eating mindfully: we often eat a sugary snack because we are not tuned into our body's hunger signals. So before reaching for that biscuit, ask yourself these questions: How hungry am I on a scale of one to 10? If it's less than eight, you're not really hungry. Am I just bored or in need of a break? Perhaps have a cup of tea instead. Can I ride this out until the next meal?

▌吃甜點(diǎn)的時(shí)候，盡情地享受它

當(dāng)選擇享用甜點(diǎn)時(shí)，應(yīng)當(dāng)通過(guò)提升進(jìn)食儀式感來(lái)獲得更大滿足，而非陷入“偷吃-愧疚”的惡性循環(huán)。研究顯示，專注進(jìn)食可提升多巴胺分泌效率，這意味著更小的分量就能獲得同等的愉悅感。

Use a plate, sit down and enjoy your snack. You can make more nutritious sweet treats too. Have a square of dark chocolate with a teaspoon of nut butter to satisfy your sweet tooth in a more sustaining way. To put it simply, a holistic approach is the best way to deal with sugar cravings.

科學(xué)控糖沒(méi)有捷徑可走。堅(jiān)持健康飲食、適量運(yùn)動(dòng)和保持良好心態(tài)，才是減少糖分依賴的最佳方法。

編輯：黎霈融

實(shí)習(xí)生：楊婧怡

來(lái)源：生命時(shí)報(bào) 閱外刊學(xué)英語(yǔ)

China Daily精讀計(jì)劃

每天20分鐘，英語(yǔ)全面提升！