金融時(shí)報(bào):生酮飲食助燃運(yùn)動(dòng)潛力

生酮飲食助燃運(yùn)動(dòng)潛力

由于生酮飲食中只攝取少量的糖類，肝臟便會(huì)將脂肪轉(zhuǎn)換成脂肪酸和酮體。酮體運(yùn)經(jīng)腦部，取代葡萄糖作為能量來源

測(cè)試中可能遇到的詞匯和知識(shí)：

starvation餓死；挨餓；絕食[stɑ?'ve??n]

glycogen糖原['gla?k?d?(?)n]

carbohydrate[有化] 碳水化合物[kɑ?b?'ha?dre?t]

ketone酮['ki?t??n]

rationale基本原理[,r???'nɑ?l]

hitting the wall撞墻期（長跑運(yùn)動(dòng)員突然跑不動(dòng)了）

lean瘦的；貧乏的[li?n]

ketogenic diets生酮飲食

saturated fat飽和脂肪

one-size-fits-all萬全之策

hormone激素，荷爾蒙['h??m??n]

A low-carb diet to fuel athletes longer （554words）

By Charles Wallace

What do some extreme distance runners have in common with the athletes at the Tour de France cycle race? Suddenly, everyone seems to be talking about adopting a high-fat diet.

The idea behind these diets is that when humans enter starvation mode, their bodies are able to switch from burning glycogen, the sugars produced by eating a meal including carbohydrates, to burning stored body fat which is released into the bloodstream as ketones. These extremely low carbohydrate diets are called ketogenic.

The rationale is that there is only about 40 minutes of glycogen stored in leg muscles, which is why runners have to keep gulping down sweets during marathons or they end up “hitting the wall” two-thirds of the way through the race.

But even lean athletes have several pounds of stored fat reserves, so if those could be tapped, you could cycle for hours without running out of fuel. So some Tour de France cyclists have started using this approach.

What's tempting more athletes to try ketogenic diets is recent research that casts doubt on the link between saturated fat in the diet and heart disease. But I asked Peter Attia, a medical doctor who practises in New York and southern California, and who also happens to be a cycling enthusiast, his view on the persistent medical concerns about fat.

Dr Attia, who spent three years on a ketogenic diet, has written about his experiences on his blog, where he gives a scientist's explanation of how the diet works.

He says it made him “far more metabolically flexible and efficient” as a cyclist. So would he recommend that his patients go on a ketogenic diet, which usually means eating very few carbohydrates? He would in about only a third of cases.

His point is that there are no one-size-fits-all diets out there. What works for one person may not work for others. Some people perform better by eating more fats, while others actually do better in endurance by eating a lot of nonprocessed carbs such as vegetables. And a lot of an individual's response to nutrition is determined by genetic make-up.

Dr Attia suggests that before going ketogenic, athletes work with a sport-orientated physician to determine if such a diet would be beneficial or even safe. You need to get blood tests before and during the diet to make sure you are not experiencing a sudden increase in small-sized low-density lipoprotein (LDL) particles, or triglycerides, which are known contributors to heart disease.

He also points out that, while it might be low in carbohydrates, the ketogenic diet is not actually a high protein diet — too much animal protein can cause a rise in IGF-1, which controls growth hormone and, at high levels, has been associated with cancer. Healthy fats can be obtained through foods such as coconut oil, avocados and nuts but many prefer to pile on the bacon and butter.

Other concerns about low-carb diets include the effect these regimes have on gut bacteria, which mainly ferment undigested starches such as vegetable fibre and produce short-chain fatty acids that help protect your gut. Because these diets are low in fibre, athletes have reported issues with constipation.

Ketogenic diets are probably best for short-term periods of training only and should not be considered a lifestyle choice. The long-term effects have not been assessed.

請(qǐng)根據(jù)你所讀到的文章內(nèi)容，完成以下自測(cè)題目：

1.What kind of nutrient could produce sugars in the body?

A.vitamin

B.inorganic salt

C.lipid

D.carbohydrate

答案(1)

2.How long does glycogen store in leg muscles?

A.30 minutes

B.40 minutes

C.50 minutes

D.60 minutes

答案(2)

3.How many years did Dr. Attia spend on a ketogenic diet?

A.1

B.2

C.3

D.5

答案(3)

4.Which one of the following is wrong about ketogenic diet?

A.it may cause constipation

B.it is best for long -term periods of training

C.the effect varies with the individual

D.vegetable fat is better than animal fat

答案(4)

* * *

(1)答案：D.carbohydrate

解釋：饑餓模式下身體會(huì)燃燒糖原，這些糖原來自于食物中的碳水化合物。

(2)答案：B.40 minutes

解釋：糖原大約可以在腿部肌肉中存儲(chǔ)40分鐘，這就是為什么在馬拉松途中運(yùn)動(dòng)員需要補(bǔ)充大量甜食和在三分之二處會(huì)覺得突然跑不動(dòng)了。

(3)答案：C.3

解釋：Dr. Attia堅(jiān)持了三年生酮飲食，并且感覺“新陳代謝提高，并且更加高效了”。

(4)答案：B.it is best for long -term periods of training

解釋：生酮飲食最好短期時(shí)間的訓(xùn)練，而不應(yīng)被視為一種生活方式的選擇，長期影響還沒有評(píng)估。