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  • we don't talk a lot about dietary science here on scishow because frankly

  • it can seem like a hype factory design more generate clicks then to generate

  • understanding people want to hear what to eat and what not to eat in order to

  • be healthy

  • the problem with that is that it's complicated it's too complicated to fit

  • into a headline eating lots of fat will make you unhealthy but so will eating

  • lots of anything studies show that cutting fat intake is useless when

  • attempting to help people lose weight if those calories are replaced by something

  • else which they tend to be

  • now that is relatively straightforward chemically but it's boggled dietary

  • scientists and especially journalists writing about it for decades but the

  • basics of what we understand aren't that complicated

  • so let's get to the heart of fat

  • fats are molecules that organisms used to store energy they are very good at

  • that and so they can be converted into lots and lots of energy for running an

  • organism

  • whether it's a seed growing into a plant or a neuron firing in your brain

  • but basically the first thing to know about fat is that it is energy dense so

  • per gram of fat has more than twice the energy of protein or carbohydrates

  • that's like everything we eat are made of chemicals and those chemicals are

  • primarily composed of long chains of carbon atoms each of those carbon-carbon

  • bonds can be broken by your body and converted into usable energy the energy

  • density of fat combined with the fact that people who ate high-fat diets tend

  • to be less healthy was the original cause of the anti-fat craze that started

  • in the sixties and continues at least to some extent today but it turns out that

  • fats are not inherently bad for you indeed they are an absolutely necessary

  • part of the diet but there are definitely some fat that promote health

  • more than others and some that are downright dangerous

  • you've heard of the main categories get to trans saturated or unsaturated

  • hydrogenated polyunsaturated omega-3 all of these words are chemistry terms that

  • get talked about a lot without discussing what they mean like at all

  • but this is a show so let's go there carbon has four unpaired electrons so

  • each carbon likes to bond to 4 other things this is methane carbon bonded to

  • four hydrogen's and yes I'm using snatam Barrett a Siam's molecular modeling kit

  • which I'm really excited about if the carbon is in a saturated carbon chain

  • two of those things will be other carbons unless it's the end of the chain

  • and two of those things are going to be hydrogen if this is what the carbon

  • chain looks like with a bunch of carbon atoms each bonded to two carbons and the

  • two hydrogen's that is a saturated fat which tend to be solid and are mostly

  • made by animals though also coconuts the thing that saturated fats are saturated

  • with is hydrogen

  • every carbon is bonded to two of them except for the last which is bonded to

  • three and unsaturated fats are not saturated they have fewer hydrogen's how

  • they've got at least one double bond between two carbons in the chain each

  • double bond means to fewer hydrogen's so unsaturated fats don't have as many

  • hydrogen's as they could have / carbon atom and this is not as minor a change

  • as it might sound single bonds can rotate around their axis no problem but

  • double bonds lock a structure into place and that double bond can either lock the

  • chain into a kink or lock it straight in nature a double bond in a fat chain

  • almost always

  • locks it into a king this prevents the fat molecules from stacking into

  • lattices making them more likely to be liquid at room temperature so

  • unsaturated fats tend to be liquid making them oils and come mostly from

  • plants and fish the case configuration is called the cis isomer

  • and the straight one is the trans isomer what isomer just means

  • that the molecules have the same chemical formula but are different

  • shapes and the different shapes matter a lot

  • saturated fats are less healthy than unsaturated fats because they packed

  • together easily and conform plaques in your arteries and can also interact with cholesterol

  • making it build up in your bloodstream cis unsaturated fats which

  • the rest of the world just calls unsaturated fats don't stack well and so

  • don't form plaques so that difference exists but it isn't as big as we used to

  • think it was it turns out that our bodies are pretty good at dealing with

  • whatever we throw at it as long as it's fairly familiar worse by far are the

  • trans unsaturated fats

  • these are almost all manufactured by adding hydrogen's or partially

  • hydrogenated some unsaturated fat like soybean oil so trans fat and

  • hydrogenated fats are the same thing

  • one refers to the process through which they are created in the other their

  • chemical structure

  • these are fat that have double bonds and stack well in fact they stack even

  • better than saturated fats and our biochemical systems are designed to

  • break them down and they interact badly with cholesterol a two percent increase

  • in daily intake of trans fat corresponds with a twenty-three percent increase in

  • the chance of heart disease amazingly they were initially seen as a healthy

  • alternative to saturated fats and are now in the process of being completely

  • banned in America now even inside these categories there's a ton of variation

  • and inside that variation comes more active areas of research which is less

  • known for sure

  • polyunsaturated fats are fats with more than one double bond might be more or

  • less healthy than monounsaturated fats no one really agrees because they both

  • have benefits and drawbacks and it matters where in the chain the double

  • bonds are you should probably have some of both

  • and if the double bond is just before the third carbon from the end we call

  • that an omega-3 fatty acid and they seem to have a wide range of benefits they

  • are also one of the two essential fatty acids the other being omega-6 essential

  • compounds are chemicals that our bodies need to function correctly but can't

  • manufacture on their own so we literally need to eat those kinds of fats in order

  • to survive and indeed we need to eat fat in general to survive it's good

  • for you in the correct quantities so those are the basics of fat you guys

  • they have tons of energy in them so they're great when you need calories but

  • they also make it super easy to eat too many calories they are absolutely

  • necessary for life they taste good and are good for you but unsaturated fats

  • are better and trans fats bite very will kill you thank you for watching this

  • episode of scishow which was brought to you by our patrons on patreon if you

  • want to help support the show you can go to patreon.com/scishow

  • and if you're interested in statins i'm not sure if the Kickstarter is still

  • going on but they're basically these little magnetic modeling guess they're

  • very cool we'll put a link in the description

  • yeah

we don't talk a lot about dietary science here on scishow because frankly

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脂肪との取引 (The Deal with Fat)

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    INN に公開 2021 年 01 月 14 日
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