B2 中高級 美國腔 93744 分類 收藏
Ever counted calories using nutritional labels?
Well just how accurate are they anyway?
Hi guys, Julia here for DNews. Food labels are great. They give you an estimate of how
many calories are in any certain food.
But they have a tiny bit of a flaw.
They fail to take into account cooking.
So we end up with a system that likely
overestimates the calories available in unprocessed food
and underestimates the calories in processed food.
The way we currently count calories is based on the Atwater System,
which is at least a hundred years old.
The System standardized the idea of the amount of energy available in food,
9 calories in a gram of fat or 4 calories in every gram of protein.
But this measures the availability of energy in food, not the digestibility.
A calorie is a unit of energy.
It's technically the amount of energy needed to heat up a kilogram of water by 1 degree celsius.
Our body burns calories in food through metabolizing the carbohydrates
and proteins and whatnot into smaller molecules our body can use as energy.
Cooking food changes how many calories are digestible.
Take potatoes for example.
When raw, the sugar molecules in potatoes
are too tightly packed for our digestive system to handle.
Cooking causes the starches in the potato to gelatinize.
That process allows us to access the sugars stored in the starch,
so we get MORE calories out of the cooked potato.
On top of that, the type of cooking method might change the chemistry of food as well -
whether it’s boiled, baked or microwaved.
On the other hand, digesting raw food takes work, a stick of celery might have 10 calories,
but the chewing and digesting burns about half of them.
All that work means there are fewer calories for your body to absorb for energy.
But before you go nibbling on an all-carrot diet, consider this. :
For our ancestors, cooking meant the difference between life and death.
The invention of a cooked meal might have changed everything.
Cooking food provided more energy and led to humans with bigger brains and bigger babies.
And people who consume an all-raw diet now, might not be getting enough calories
even when eating food packed with nutrients.
Some women on an all-raw diet get irregular menstrual cycles, a sign of under-nourishment.
Not to mention the bacteria in your gut steal a few of the calories for themselves.
So the exact number of calories you’re getting is affected by
way too many factors for those labels to be truly accurate.
But while modifications to the Atwater system have improved it some over the years,
there’s still no real alternative.
So until nutrition scientists come up with a better calorie counting system take food labels with a grain of salt. See what I did there?
Switching gears for a second, I wanna let you know that tomorrow Trace, Amy and Ian
are gonna be chatting with a real live astronaut about what it’s like to live and work in space.
And if you wanna hang out with the space nerds, be sure to RSVP using the link
we’ve got in the description. That’s at 3pm Eastern time, Noon Pacific.
So do you trust nutritional labels? Do they need to be updated?
Leave your thoughts and comments below and
don’t forget to subscribe for more DNews everyday.



你真的可以相信食物上的熱量標示嗎?( Can You Trust The Calorie Counts On Food Labels? )

93744 分類 收藏
Derrick Chen 發佈於 2017 年 7 月 22 日    Derrick Chen 翻譯    王妍心 審核
  1. 1. 單字查詢


  2. 2. 單句重複播放


  3. 3. 使用快速鍵


  4. 4. 關閉語言字幕


  5. 5. 內嵌播放器


  6. 6. 展開播放器


  1. 英文聽力測驗


  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔