The Deal with Carbs


A lot of people think carbohydrates are the
enemy.
The word might make you think of spaghetti,
white bread, or other foods that’ll supposedly
make you gain weight.
But dietary science is more complicated than
that, and carbs are also found in fruits,
grains, vegetables, and milk.
They help you make and store energy, poop
a little better, and are one of the three
classes of macronutrients that you need to
live.
Chemically, carbs are pretty simple: just
carbon, hydrogen, and oxygen.
Hence the name – “carbo” for the carbons
and “hydrate” for water.
But not all carbs are the same.
There are simple carbohydrates – the monosaccharides
and disaccharides – and complex carbohydrates,
or polysaccharides.
These words just describe the structure of
the molecules – so, monosaccharides are
the basic building blocks of longer carbohydrate
chains.
Monosaccharides are also commonly called simple
sugars, and taste sweet.
Like, you’ve probably heard of glucose.
We can thank plants for glucose – and, really,
for most carbohydrates that we eat – because
they convert carbon dioxide and water into
glucose during photosynthesis.
There are also molecules like fructose, which
is found in some fruits and honey, and galactose,
which is in milk.
All three of these molecules are isomers,
so they have the same chemical formula, but
their atoms are arranged differently.
This gives them different chemical properties,
like levels of sweetness.
Now, the taste of sugars is great, but carbs
are really important because they’re a great
source of energy.
Glucose metabolism is basically when glucose
undergoes a bunch of chemical reactions in
cells to make these molecules called ATP.
And cells in your body use chemical energy
from ATP to do pretty much everything – move,
grow, especially keep your brain functioning.
So, monosaccharides are small enough to pass
from your intestines into your bloodstream,
and then into different cells in your body
that starts these energy-producing chemical
reactions.
But lots of the carbs we eat aren’t plain
old monosaccharides.
When two are bonded together, you get a disaccharide
– like maltose, which makes cooked sweet
potatoes sweet, sucrose, which is table sugar,
and lactose, the sugar in milk.
These have to be digested by enzymes before
they can enter your bloodstream.
Some people can’t break them all down, though,
like if you’re lactose-intolerant.
So bacteria might do it instead, which can
make you feel all gassy and bloated.
And polysaccharides, or complex carbs, are
just a bunch of monosaccharides bonded together.
Like, starch is a long chain of glucose molecules
that plants use to store energy.
You have enzymes that can break down starch
from foods like grains or potatoes, but it
takes a little longer to digest and absorb
than monosaccharide-filled foods, like candy
bars.
On the other hand, we store extra glucose
in the form of glycogen, mostly in our liver
and skeletal muscle cells.
See, there’s this chemical produced by your
pancreas called insulin that helps regulate
your blood sugar.
When you have too much glucose in your bloodstream,
more insulin is released.
And it basically tells your body to start
making glycogen, to store for later when you
need energy.
And glycogen is the reason that endurance
athletes, like marathon runners, will sometimes
eat a bunch of carbs before exercising.
They’re trying to store more glycogen, so
when their body needs energy, their cells
can break those polysaccharides down and have
lots of glucose to metabolize.
But here’s the catch: you can only store
so much.
And when your liver and skeletal muscle cells
can’t hold anymore, any extra glucose will
be converted into energy-dense fats for storage.
Sound familiar?
That fear that eating too many carbs makes
you fat?
So that’s why people might go on low-carb
diets – to avoid making and storing more
fat molecules, even though eating carbs in
moderation is not unhealthy.
If your body runs low on carbohydrate fuels,
it’ll start to metabolize these fats to
make energy instead.
There are different chemical reactions involved,
and different byproducts get created.
But if you completely eliminate carbs from
your diet, your body might not get enough
fiber, which is a group of compounds – including
some complex carbohydrates – that we don’t
have the enzymes to digest.
At first, that doesn’t seem at all helpful,
because we typically eat food to give our
bodies energy or chemical building blocks
to make more stuff.
But some kinds of fiber – like cellulose,
a polysaccharide that gives plants structural
support – help promote healthy bowel movements
by adding bulk to your stool.
And other kinds of fiber can dissolve in water,
forming a sludgy mixture that can reduce your
LDL cholesterol levels – the kind that can
build up in your bloodstream and be dangerous.
These fiber molecules bind to cholesterol
and these chemicals called bile acids – which
are made from cholesterol – in your intestines,
so you excrete them.
So fiber is your friend, and you shouldn’t
be afraid of carbohydrates.
They’re important nutrients, can taste delicious,
and give your body lots of energy.
But it is possible to have too much of a good
thing.
Thank you for watching this episode of SciShow,
which was brought to you by our patrons on
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100 thoughts on “The Deal with Carbs

  • I was part of a group in my small group communications class and we had to all pick a topic and each do a presentation on something from that topic. My group chose Nutrition and we had Vitamins, Water, Protein, and I picked Carbs. I had fun talking about the bad and following it up with the good making carbs seem like an anti-hero of Nutrition while the other 3 were the traditional good guys.

  • I dare not try to tell someone what they should eat, it is practically religion for some people – I'm looking at you, Vegans. However, the food industry packs a LOT of added sugars and carbs into our food making it unbelievably easy to get more than you need. I have found that a high fat, very low carb diet works best for me.

  • There is no such thing as an essential Carbohydrate, you do not need carbohydrates to live.
    The human body can and will metabolize fat and proteins more efficiently and lead to less obesity, diabetes and fatty liver disease if you remove as many carbohydrates as possible from your diet.
    k

  • I think it is refined carbohydrates that do the damage – sugar in everything that do the following (suprised this was missed out of the talk):

    High glycemic load induces high insulin that stores the blood glucose and paradoxically leaves one hypoglycemic, not-full and ready to eat more.

    Non-carb diets are more for rapid weight loss, hard to maintain as lots of traditional foodstuffs are carbohydrate based. Thankfully the British staple, the full English breakfast, can be modified slightly to be low-carbohydrate, high protien and high fat – leaving you full well past lunch.

    I am out in the USA and had a stack of pancakes (heavy refined carbohydrates) with maple syrup – obviously this is unhealthy but I had 1500 calories from that and felt hungry within 2 hours. The same calories in a fatty full English leave you full for half a day.

    Additionally, net-carbs (carbohydrate minus fibre) is what most dieters use these days, no need to stick up for fibre, no-one is saying you dont need it.

    Hope Sci Show goes more into the science next time.

  • Hey can you guys enplane the science behind a Ketogenic die ei high fat low crab diet. That's what I've been doing for around a month with around 5% of my calories coming from carbs and I've been fine.

  • I don't get how much of an idiot you need to be to overconsume anything… Just eat small portions, wait 15-20 minutes after a meal and see if you're still feeling a need to eat, if so, munch on a fruit or vegetable or some nuts, and eat a small portion a few hours later… I eat mostly carbs with very little meat, and I'm generally the healthiest every health exam my class goes through

    Just because people are stupid, doesn't mean a diet is bad…

  • Trying to get up to a subway sandwitch, have you seen their avacadoes? A leaf takes 6 hours to decay, so you can't just run around with fresh produce. Also, their bread is really thick, its always fresh. A safeway sandwitch is just getting hard and stale, it is very fine tuned to have a subway in your car or truck.

  • u'r cool dude, make a video about how to regulate glucose intake to not sollicitate insulin release and go over the liver/muscle glycogen levels!!

  • The reason low-carb diets work should be pretty obvious, the fact that they are significantly less efficient, is what makes them more efficient at losing weight.
    Fact: Calories Out > Calories In = loss of body fat (and muscle and… and… and…)
    assume you burn-off precisely 2000 Calories per day.
    You consume 2000 Calories worth of A, and convert it to energy at 99.9% efficiency; you are at a net loss of 2 calories.
    You consume 2000 Calories worth of B, and convert it to energy at 80.0% efficiency; you are at a net loss of 400 calories.
    Clearly the lower efficiency non-carb diet is the way to go if weight loss is the goal.
    Hidden diet option C is not allowing your body to have a fair chance at converting food to energy. More fiber, more water, any kind of laxative or diuretic can definitely make your body better at producing waste; which means it's worse at producing energy, which means it's going to store less, or even start dipping into those stores.

  • It is a very popular belief that people think carbs are bad for you when in fact 45-65% of your calories in your diet should come from carbs. The problem in America is that we love our carbs. We love our breads and pastas and sweets, we often eat too many carbs and that leads to weight gain. However, eating too much of anything leads to weight gain. We blame the majority of our weight gain problems on carbohydrates because we eat too much of them. Eating too much of anything gets stored as fat just as much as carbohydrates do. When people do “no carb diets” they might be losing weight because you’re not consuming nearly as much carbs as you used to, but you’re also losing a lot of energy because the majority of our energy is made from the intake of carbs and that is why the percent of calories from carbs is the highest of the macronutrients. Low carb/No carb diets aren’t good for you, because your body needs carbohydrates, just not over the limit.

  • You dont need carbs to live, in fact your body can function normally without eating any !

    Of course you need Glucose but your body knows how to break your fat cells into glucose to give you energy, that is how fat loss occurs. So the best way to loose weight is to cut the carbs, and you will feel good too !

  • Good video and great job talking sense about a subject that many people are hysterical about and tend to ignore the science almost completely. However, I do have one nit-pick: carbohydrates are not a "macronutrient that you need to live."

    Unlike essential nutrients such as the essential amino acids and the omega fatty acids, carbohydrates need not be consumed in the diet. Yes, one's brain does need glucose but after an adaptation period, it can derive as much as 75% of its energy needs from ketone bodies created from fat metabolism. Glucose is required for the remaining 25% but it can be produced in the liver via gluconeognensis from glycerol (a byproduct of fat metabolism) or from certain amino acids (alanine, glutamine, etc.). So while a small amount is required, it can be produced by the body and is therefore not an essential nutrient (which must be consumed in the diet).

    That said, it would be difficult to imagine a diet, with the possible exception of complete starvation, that did not include at least a small amount of carbohydrates. Also, at least some carbohydrates in the forms of soluble and insoluble fiber, plus probably some digestible carbohydrate, would be included in an optimal diet.

  • It's misleading when you said "we need carbohydrates to live." Yes, but we do not need to EAT carbohydrates to live. Our body is perfectly capable of manufacturing them from fat.

  • People need to stop using the word "Carbohydrates" to refer to sugars/alcohols. Most fibre and many fatty acids fall under that classification. It is a chemistry term, and should see little use in physiological discussion.

  • I recommend "Anatomy for beginners" to everyone who has a "strong stomach". In the circulation lesson you can see the huge difference between a healthy artery and a damaged one.
    Damage to it is due to plaque inside it, it reduces blood flow, forces the heart to pump harder, increases the pressure inside the circulatory system, and bulges the arteries.
    You can see in the live dissection how fat actually goes everywhere in the body, between intestines, on organs, inside arteries.

    I'm not a MD but from my knowledge I came to the conclusion that the body can deal with everything we eat, as long as we have smooth arteries, a strong heart (since it's a muscle), and efficient lungs. You can see where I'm going with this, as long as you do sufficient cardio activities, you can stuff yourself with pizza and ice cream and be just fine.

  • I'm vegetarian and almost everything I eat is carbs, but I'm still skinny. (Bread, pasta, potatoes, ice cream, rice….. donuts) Someone explain this to me.

  • Here from 9th grade chemistry class… It took 4 minutes to explain from you and 2 hours from the teacher! Thanks 😉

  • I misread the title and thought it said "What's the Deal with Cards?"
    Could you do one on why the "Card" component of web design is gaining such steam?

  • You nailed it. People should eat enough carbs to refill their muscles. They will have the energy ready for their next exercice which should be the next day ideally. Unfortunately many people sit around, eat very dense foods, store the fat, turn the sugar into a little more fat and get into trouble. They then follow some fad like the keto diet. The real answer is to cook vegetables instead of gorging on carbs covered with oil. Veggies, a few complex carbs as whole grains or fruits and the human will thrive.

  • I'm a proponent of the Atkin's Diet, which basically tells you to eat as much carbs as your body can handle. Each person has a specific "carb tolerance" that depends mostly on genetics. You start out with an allotment of 20 grams of carbs a day to get your body into fat-burning mode, then gradually increase your allotment until you hit your carb tolerance. You definitely know when you hit your limit, because you experience gas, bloating, sometimes nausea or even vomiting, and usually intense carb cravings. Then you go back down, and that's your limit. You keep eating few enough carbs to keep your body burning fat.

  • Is this the reason why I feel like I can actually get up in the morning if I've had a carby meal the night before? As opposed to no dinner and feeling like I need someone to recusitate me the next morning?

  • Is this the reason why I feel like I can actually get up in the morning if I've had a carby meal the night before? As opposed to no dinner and feeling like I need someone to recusitate me the next morning?

  • It's funny how some people start out liking Galactose, but then end up Galactose intolerant. Like the Silver Surfer.

  • i think theres a lot of asterixes that could be put in here because even though no lies were told, this draws an incomplete picture of the human metabolism of carbohydrates. for example the sacharide called fructose doesn't do anything for energy and gets treated like a toxin (pretty much the same way as alcohol) within your liver and turned into fat. so half the sucrose (or just plain sugar) gets turned into fat. it's a biological fact. do i have my facts straight or did i watch some bs on youtube?

  • NEVER STOP MAKING VIDEOS! 90% of your videos contain essential knowledge that every human should understand completely yet, sadly, we live in a world where opinions run EVERYTHING! I hope that, one day, intellectual and rational thoughts will prevail for the betterment of our species but sadly, I view that as a wish rather than a possibility

  • You can easily get enough fiber by chewing on matchsticks or any wooden stuff like that. I did that when I tried to get rid of my nicotine addiction. I never got rid of it really, but my bowels loved me in the meantime.

  • "Fiber is your friend" and "You shouldn't be afraid of carbohydrates." Love it! Way to jam-pack all this information 🙂

  • This channel is so amateurish.

    People don't need carbs to live. There is nothing essential about carbs.

    Saying "carbs is one of the three food groups we need to live" is like saying "alcohol is one of the four food groups we need to live".

    While technically true, it's misleading. It's suggesting that alcohol is essential for life, which it isn't. The same goes for carbs.

  • What this video is failing to address is that de novo lipogenesis (the conversion of carbs to fat) is very inefficient. In a calorie surplus only a measly fraction of the fat gain will come from de novo lipogenesis. On the other hand, fat doesn't have to be converted to anything because it's already fat. We can radioactively label fat and see where it ends up. And sure enough, it is directly stored as fat.

    Furthermore, carbs have 4 calories per gram while fat has 9. So it will be a lot easier to end up in a calorie surplus when eating lots of fat.

  • I eat only complex carbohydrates. Being a diabetic vegan and occasionally I will have something with refined sugar but very rarely.

  • It's not that we think carbs are the enemy. I *love!* foods made with whole grain (pancakes, bread, etc.), dried beans, and potatoes.

    My relatives' and my problems are that we gain weight and are susceptible to diabetes type 2. The carbs from vegetables and fruits are sufficient for my body. Your body can probably utilize grains, dried beans, and potatoes better than my body. I blame it on genetics.

  • A lot of carbs can freak out your bowels if you have IBS. Now we know more about WHICH carbs do that, but before any of that was known, my mom found out by herself that cutting carbs from her diet stopped her from bloating. Personally I'm mostly sensitive to oligosaccharides, which are very abundant in onions for example. Just eating a little bit of onion in meal can give me cramps for over a week.

  • turns on flashlight at dramatic angle next to campfire
    Them carbs are gonna gitchya just you wait.. three slices of bread and you're done for!

  • carbs , fats, protein are all good and needed , but for each of them the source matters the most , get carbs from fruits and veggies and you will be doing a favour to your body

  • Okay but most low carb diets say not to count fiber. So if you eat something with 6g carbs, 3g fiber, you only account for 3g of carbs. I'm not arguing that low carb is more effective at burning fat. Just that for some people it might help keep them from eating too many calories..

  • So is there anything wrong with going low-carb but also taking a fiber supplement? Not that I’ll ever actually follow through with any kind of diet. Haha

  • I thought the title was 'The deal with cards' , and that thing the man was holding in the thumnail, I thought it was a stack of cards,

  • There is no such thing as an essential carbohydrate. Your liver and tissues produce and store enough glucose for your brain and organs. Did I write anything that is untrue? Why goes everyone assume that carbs snd glucose intake is the default diet (SAD diet) when significant production of bread, pasta, refined grains and flour might have been available for the last 2000-3000 years of human evolution at best.

  • LIAR! There is ZERO scientific evidence that we need any carbs in our diet. There is a plethora of evidence that we don't need them at all. We can live our entire lives with zero carbs. Our bodies run far better on ketone bodies than carbs. Insulin causes weight gain, by forcing fat storage and preventing fat metabolism. Carbs do not become fat, they are stored in fat and slow or prevent the ability to break down that fat. This entire video is based on false and out dated information.

  • Being a Type 1 Diabetic, I know all too well how a lack of glucose in your bloodstream can lead to your brain shutting down. More than once, I’ve lost consciousness due to dangerous hypoglycemia. People whose bodies process carbohydrates properly have no idea how privileged they are to not have to constantly worry about this.

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