The ketogenic diet, or keto for short.

生酮飲食減肥法，簡稱「生酮飲食」。

Celebrities like Halle Berry, Kourtney Kardashian, and Vanessa Hudgens all swear by it.

諸如荷莉．貝瑞、寇特妮．卡戴珊和凡妮莎．哈金斯等名人都深信其效。

And if losing weight is your goal, keto works.

如果你的目標是減肥，那生酮飲食很有效。

It's proven to help you shed pounds fast.

它被證實能幫助你快速減重。

But there's more to this diet than meets the eye.

但這種飲食法並不像表面上看起來那麼簡單。

Keto basically replaces carbs with fat.

生酮飲食基本上是以脂肪取代碳水化合物。

A typical keto diet looks like this: 70% fat, 25% protein, and 5% carbohydrates.

最典型的生酮飲食是這樣的：70% 脂肪、25% 蛋白質和 5% 碳水化合物。

It's a drastic change from the diet that the USDA recommends for most Americans,

相較於美國農業部給美國人的飲食建議，這是極大的改變，

which is less than 30% fat, 20 to 35% protein, and at least 50% carbs.

而農業部的建議是低於 30% 的脂肪、20 至 30% 的蛋白質以及至少 50% 的碳水化合物。

And it's a significant change for your body's metabolism, too.

而它對你身體的新陳代謝也是一個重大變化。

Usually, when you eat carbs like a starchy potato, enzymes in your mouth, stomach, and small intestines break them down into a form of sugar energy called glucose, which your brain and body use for fuel.

通常在食用如馬鈴薯等富含碳水化合物的食品時，口腔、胃和小腸中的酶會將其分解成一種稱為「葡萄糖」的糖能量，作為大腦和身體的燃料。

So, when you first skip out on carbs, the first couple days, you might experience some strong sugar cravings.

所以當你開始戒碳水化合物的前幾天，可能會感受到對糖分的渴望。

That's because your body is switching gears, from converting carbohydrates to the only energy it has left, fat.

那是因為你的身體正在換檔，從分解碳水化合物轉換成分解體內僅存的能量：脂肪。

Once you're burning fat regularly, you'll see those pounds start to melt away.

當燃燒脂肪成為常態，你就會發現體重開始下降。

Depending on your weight, you might lose up to 3.5 pounds within that first week.

根據體重的不同，你可能在第一週就減掉高達 3.5 磅（約 1.6 公斤）的重量。

As you burn more fat, levels of insulin, the fat-storing hormone, will drop significantly.

隨著更多脂肪被燃燒掉，做為脂肪儲存激素的胰島素數值會大幅下降。

This triggers your kidneys to release large amounts of sodium into the blood, which can actually lead to a common side effect known as the keto flu.

這將會觸發腎臟釋放大量的鈉至血液中，並可能引起常見的副作用，也就是所謂的「生酮不適症」。

Many keto dieters report symptoms like nausea, headaches, dizziness, muscle cramps, and low energy levels.

許多生酮飲食減重者遇到的症狀有噁心、頭痛、暈眩、肌肉痙攣與精神不振。

But most of these symptoms will only occur within the first couple weeks of starting the diet.

但大部分的症狀只會發生在實行生酮飲食後的前幾週。

After the first month, the scales will look better, but some of that lost weight isn't actually fat; it's just water.

一個月過後，體重計上的數字會比較順眼，但減掉的體重並不全是脂肪，有些只是水份。

Because some of the carbs you metabolized include glycogen, which retains water, and therefore helps keep you hydrated,

因為你代謝掉的部分碳水化合物包括能夠幫助人體保留並擁有充足水份的糖原，

as a result, you're likely to pee more often, which will lower your sodium levels even more, leading to dehydration, constipation or diarrhea, and bad breath.

你可能會因此更頻尿，進一步降低你體內的鈉含量，甚至導致脫水、便祕或腹瀉以及口臭。

Once you're a couple months in, you might hit the notorious keto plateau.

實踐生酮飲食的幾個月後，你可能會遇到惡名昭彰的生酮減重撞牆期。

It's a common term in the keto community.

這是在生酮飲食界常見的術語。

It refers to when people find it progressively harder to continue to lose more weight.

它意味著人們發現要減去更多體重這件事變得越來越困難。

One study, for example, found that overweight people lost an average of 15 pounds in the first month, another 11 pounds over the next two months,

舉例來說，一項研究發現，過重的人在第一個月平均減了 15 磅（約 6.8 公斤）、接下來兩個月可以再減 11 磅（約 5 公斤），

but after that, they saw no change in body weight despite sticking to the keto diet.

但在那之後，儘管繼續實踐生酮飲食，體重仍毫無變化。

At this point, many people will just quit keto.

這時，很多人就會直接放棄生酮飲食。

That's why researchers often find it so hard to study the long-term effects of the diet.

研究人員也因此常難以對生酮飲食效用做長期的研究。

But, as it turns out, there's one group that typically sticks to keto for a really long time.

但事實證明，還是有一群可以長期堅持生酮飲食的人。

It's unclear why, but keto is proven to reduce the symptoms of epilepsy,

目前原因未明，但生酮飲食被證實可以減緩癲癇的症狀，

and studies show that epileptic children who stay on a very restricted keto diet for several years can suffer from kidney stones, high cholesterol, and bone fractures.

研究也顯示，患有癲癇的孩童如果多年實行非常極端的生酮飲食，可能會出現腎結石、高膽固醇和骨折等症狀。

But a typical keto diet won't be nearly as strict.

但普遍的生酮飲食減肥法沒有那麼嚴格。

And if you wanna try keto, you should talk to your doctor first.

如果你也想試試生酮飲食，還是先跟醫生諮詢一下。

In the meantime, go ahead and get that bread.

同一時間，吃點麵包也無妨。

And remember, the best diet is a balanced one of fat, protein, and yes, even carbs.

然後記得，最好的飲食法就是均衡地攝取脂肪、蛋白質，還有，沒錯，碳水化合物。