low carb high fat diet pros and cons

we don’t talk a lot about dietary sciencehere on scishow because, frankly, it can seem like a hype factory designed more to generateclicks than to generate understanding. people want to hear what to eat and what not to eatin 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

low carb high fat diet pros and cons, show that cutting fat intake is useless whenattempting to help people lose weight if those calories are replaced by something else, whichthey tend to be. now fat is relatively straightforward chemically,but it’s boggled dietary scientists and, especially, journalists writing about it fordecades. but the basics of what we understand

aren’t that complicated, so let’s getto the heart of fat. fats are molecules that organisms use to storeenergy...they are very good at that and so they can be converted into lots and lots ofenergy for running an organism, whether it’s a seed growing into a plant or a neuron firingin your brain. fat is super good at energy storage. in nutrition,we talk about energy in “calories” which is really a measure of heat. but, basically, the first thing to know aboutfat is that it is energy dense. so per gram, fat has more than twice the energy of proteinor carbohydrates. fats, like everything we eat, are made ofchemicals. and those chemicals are primarily

composed of large 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 thefact that people who ate high fat diets tended to be less healthy was the original causeof the anti-fat craze that started in the 60s and continues at least to some extenttoday. but it turns out that fats are not inherentlybad for you, indeed, they are an absolutely necessary part of the diet. but there are definitely some fats that promotehealth more than others, and some that are downright dangerous. you’ve heard of themain categories:

you got your trans, saturated, unsaturated,hydrogenated, polyunsaturated, omega 3...all of these words are chemistry terms that gettalked about a lot without discussing what they mean, like, at all. but this is scishow, so let’s go there. carbon has four unpaired electrons, so eachcarbon atom likes to bond to four other things. this is methane: carbon bonded to four hydrogens.and yes, i am using snatoms-- veritasium’s molecular modeling kit which i’m very excitedabout. 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 bondedto two carbons and two hydrogens, that is a saturated fat, which tend to be solid andare mostly made by animals...though also coconuts. the thing that saturated fats are saturatedwith is hydrogen. every carbon is bonded to two of them, except the last, which is bondedto three. and unsaturated fats are not saturated. theyhave fewer hydrogens...how? well they’ve got at least one double bond between two carbonsin the chain. each double bond means two fewer hydrogens. so unsaturated fats don’t have as many hydrogensas they could have per 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 structureinto place. and that double bond can either lock the chaininto a kink or lock it straight. in nature, a double bond in a fat chain almostalways locks it into a kink. this prevents the fat molecules from stacking into latticesmaking them more likely to be liquid at room temperature. so unsaturated fats tend to beliquid, making them oils, and come mostly from plants and fish. the kinked configuration is called the “cisisomer” and the straight one is the trans isomer. the word ‘isomer’ just means thatthe molecules have the same chemical formula,

but are different shapes. and the different shapes matter...a lot. saturated fats are less healthy than unsaturatedfats because they pack together easily and can form plaques in your arteries and canalso interact with cholesterol making it build up in your bloodstream. cis unsaturated fats (which the rest of theworld just calls unsaturated fats) don’t stack well and so don’t form plaques. sothat difference exists, but it isn’t as big as we used to think it was. it turns outour bodies are pretty good at dealing with whatever we throw at it...as long as it’sfairly familiar.

worse by far are the trans unsaturated fats.these are almost all manufactured by adding hydrogens or “partially hydrogenating”some unsaturated fat like soybean oil. so trans fat and hydrogenated fats are the samething...one refers to the process through which they are created, the other their chemicalstructure. these are fats that have double bonds andstack well...in fact, they stack even better than saturated fats and our biochemical systemsaren’t designed to break them down and they interact badly with cholesterol. a two percent increase in daily intake oftrans fat corresponds with a 23% increase in the chance of heart disease. amazinglythey were initially seen as a healthy alternative

to saturated fats and are now in the processof being completely banned in america. now, even in these categories there’s variation,and inside that variation comes more active areas of research where less is known forsure. polyunsaturated fats, or fats with more thanone double bond might be more or less healthy than monounsaturated fats... no one reallyagrees because they both have benefits and drawbacks, and it matters where in the chainthe double bonds are. you should probably have some of both. and if the double bond is just before thethird carbon from the end, we call that an omega three fatty acid and they seem to havea wide range of benefits. and they’re also

one of the two essential fatty acids (theother being omega 6). essential compounds are chemicals that our bodies need to functioncorrectly but can’t manufacture on their own...so we literally need to eat those kindsof fats in order to survive. and indeed, we need to eat fat in generalto survive. it’s good for you...in the correct quantities. so those are the basics of fat you guys! theyhave tons of energy in them, so they’re great when you need calories. but they alsomake it super easy to eat too many calories. they’re absolutely necessary for life, theytaste good and are good for you, but unsaturated fats are better and trans fats might verywell kill you.

thanks for watching this episode of scishow,which was brought to you by our patrons on patreon. if you want to help support thisshow, just go to patreon.com/scishow. and if you’re interested in snatoms-- i’mnot sure if the kickstarter is still going on-- but they’re basically these littlemagnetic modeling kits. they’re very cool, we’ll put a link in the description.