How We Got the Science of Weight Loss Wrong - with Giles Yeo

[Music] thank you so much pete thank you to the ri for allowing me for allowing me to be here and and i'm here to speak about why calories don't count i know don't everyone stop i'll explain okay i've already had enough problems uh online with the with the title but hopefully um i'll clarify why why calories don't come my name is joseo i'm based at the university of cambridge um where i'm a geneticist and i'm a geneticist that works on on body weight okay and um but this is the one i'm going to talk to you about today because while i understand the biological variation of why people are different sizes and why people behave differently around food ultimately we have to also figure out and and understand the environment in particular the food environment you know genes interacting with the environment and tonight i want to talk about the environment and i want to talk about our food and i want to talk about the way we our relationship with our food and how we actually refer to it particularly with this word the calorie and so this is what uh tonight's going going to be about my book um why calories don't count it's just been published today so this is in effect it's not a de facto launch it is a launch and i launched my first book at the royal institution and i'm going to launch my second book at the royal institution so i'll go for about i don't know 40 45 minutes which will leave us plenty of time um plenty of time for questions okay so um welcome everybody uh and i'm really grateful that you have taken the time out to come and to come and actually listen listen to me so why calories don't count now i think calorie counts are ubiquitous this is not a surprise so i've got um listed here on the left hand side is the uk eu compliant labeling on the right hand side is us fda compliant uh compliant labeling the and this is the back of pack labeling up here um and this is we're still so far um in in the eu so all of these rules we still we still apply to and actually we're not but these rules we still apply to and this is the compliant front of pac front of pack labeling and here are the calorie counts so immediately what you see is you see a number of different units you see the numbers that's fine but you see on the energy you have um kj what's that kcal and you can see that kj kcal and in the u.s compliant label you actually have the word you actually have the word calories okay so what are what do do all of these nomenclature mean um and so i thought before we start the the talk we may as well just deal with what an actual calorie what is a calorie what is a calorie so now there is a small c calorie at the risk of sounding like an on sesame street okay a small c calorie is a heat calorie so this was the original way that the calorie was defined and it was defined as a unit of heat and it's the amount of energy you need to raise the temperature of one milliliter of water one degree celsius at sea level okay now the calories i'm going to be speaking about tonight and most of us talk about when we say when we bandy around the world calories are food calories okay now food calories are also known as a big c calorie i'm not making this up okay um a big c calorie or which is 1 000 small c calories so it's sometimes called a calorie or cacao which is where those numbers came from and this is the food calorie and this is the amount of energy required to raise the temperature of one liter of water one degree celsius at sea level but just for the avoidance of doubt uh for the rest of the talk and in fact in in the book when i say the word calorie okay um i mean food calorie i mean a kilo calorie now a calorie or kilo small little calorie is not a si unit it's a unit of energy but it's not a it's not an si unit the si units are going to be in joules and so one small c calorie the heat calorie is 4.184 joules or roughly 4.2 joules and so therefore the food calorie the kilo calorie is 4.2 kilojoules or kj which is where those numbers come from so a calorie can either be a big c calorie a kcal or kj and that would then be calories times 4.2 clear as mud that's the nomenclature but we're going to be talking about specifically we're going to be talking about calories tonight so here is the question okay so here's the big question why don't calories count so it's because of this because it is an equation such as it is it's not really an equation is that the number of calories actually in food does not equal the number of calories you see on the side of the pack that's the okay which does not equal the number of usable calories we actually finally get out of food okay and this is an absolute critical uh important thing to try and understand and trying to understand why this is the case requires us to actually get our head around the concept of caloric availability so caloric availability is the amount of calories that you can actually drag out of a food versus the total number of calories in the food of in in the food to begin with okay so let me just give you some some examples so you can understand what i'm talking about imagine 100 calories of sugar so if you had 100 calories of sugar um the availability of sugar which means that how many calories you get when you eat 100 calories of sugar is about 95 calories so the availability of sugar is 95 okay the caloric availability of sugar now when you actually eat sweet corn okay we all love sweet corn corn on the cob um and then look in the loo the next morning it is quite obvious we have absorbed nowhere close to 100 calories of sweet corn but yet if you take sweet corn um you desiccate it you convert it into a corn meal and you make a corn tortilla you make corn bread suddenly because of the way you have processed the kernels of corn you've done something with them you've changed its structure suddenly a far greater percentage of the calories in exactly the same source food corn is made available because it's now in a shape of a con tortilla and a form of corn bread this is what caloric availability is and so therefore what food you eat it does actually make a difference because how your body eventually tries to get the calories out um um differs from food to food okay so how are calories empirically measured okay so now this is dealing with the total number of calories in a food how are they measured well i mentioned that they're a unit of heat and so what they're actually this is still true today okay the most the the most accurate way to count every single calorie in the food is something called the bomb calorimeter all right now the bomb calorimeter the epinephrus bomb is just as unsophisticated as it sounds it involves a sealed container over here the the epinymous bomb okay where you put a sample of food all right now um wet food you have to desiccate remove the water because water has no caloric value at least two to at least it does have energy obviously equals empty square but it doesn't have actually any caloric uh of value to to humans so you can just you can just evaporate off the water and what you do is you put them into this sealed container and you burn it now this sealed container is pressurized um to 30 atmospheres 30 times the atmosphere here on earth with pure oxygen to ensure that everything is burnt to an absolute crisp you carbonize the food right surrounding um this is a known volume of water it's water jacket is a known volume of water so what happens is you put a known weight of food into the into the bomb calorimeter you burn it to a crisp and then you just simply measure the temperature rise in the water jacket next door and because one calorie one liter of water one degree celsius you then know how many calories there are in the food so this is how you measure all of the calories uh um that that are actually that are actually in the food um so well it's a unit of energy surely all calories should be equal ah you know what the problem is human beings are not bomb calorimeters now our digestion process is actually aside from the stomach which which has a a a it's a ph value of 1.5 like battery acid so i wouldn't stick your hand in there um digestion is actually a relatively time consuming but gentle process it's in effect one very long chemical reaction there's a bit of chewing in it at the end but at the end of the day it just goes through and enzymes and and acids and everything are thrown at it and then at the end of 24 hours everything is then um digested not everything okay we digest and actually absorb it so it's actually a relatively gentle process we are not furnaces we are not a bonfire we cannot extract all the calories out of all the calories out from food so this gives us a the bond gallerimeter gives us a the number of calories actually in food okay how do we get to b how do we get to the number of calories on the side of the pack of every p every item of food you buy today prepackaged food you have these numbers okay where do those numbers where do those numbers come from all right well for that we have a chap named wilbur atwater and he was a professor of chemistry at wesleyan university in connecticut um in the late 1800s okay and what he did was he appreciated and and the bomb calorimeter had been invented by the time and and at water okay realized the sweet corn effect okay he realized that obviously we were not absorbing um all the calories we were eating and he was so he was trying to figure out a way of actually trying to determine well how much food how many calories do we actually end up absorbing in into our body so what he did between 1880 and 1900 and i'm going to tell you the story and i want you guys to reflect on this the next time you feel like complaining about your job okay so what atwater did was he used a lot a lot of bomb calorimetry so what he did was first he burnt a whole heap of food okay everything beef chicken sweet corn etc etc right and worked out tried to work out the heats of combustion of each of the various things how much uh in terms of fats carbohydrates and protein he then fed those exact same foods to a human being a fasted human being it then went through the human being's system and then the next morning he then went to collect the poop okay and then he burnt the poop okay and so what he then did was now he knew how much total calories went in the top end he knew how much calories came out the bottom end using bomb calorimetry you subtract one from the other and you get the amount of calories you actually uh absorb don't complain about your job 20 years he did this so what he then did was he calculated the heat of combustion so this is the bomb calorimetry number and you can see it gives a certain number fat 9.49.3 carbs depending on whether it comes from a plant or an animal and protein you can see you can see these numbers here then after the subtraction he then got these numbers in effect he got eight point nine five eight point three five to eight point nine five per perk of calories per gram of fat anywhere from three point eight to four four carbohydrates and around three to four you know it's just kind of like a little bit of uh a wiggle room here but he just rounded the numbers up okay and so the numbers and these are called the at water factors you can you can google it the at water factors are nine calories for every gram of fat four calories for every gram of carbohydrate and four calories for every gram of protein oh for alcohol those just in case you you care here also work that out that's seven calories for every gram of alcohol so the scary thing is alcohol is actually approaching the caloric content of fats so the numbers of every single pack this was in 1900 he published his numbers okay together with these huge lists of lists of food um and if you go to the pack of any food you have in your cupboard at the moment and look and actually try and do the math you calculate how much protein you look at a pack or how much fat how much sugar the numbers are still based on these 120 year old factors okay that are there there's a little bit of wobble a little bit of wiggle room around the protein amount because people have we have changed into trying to determine into trying to figure out how much protein there is in a given food but basically all of the calorie accounts on the side of the pack are based on these numbers from 1900 from 120 years ago okay so this these are the atwater factors the 944 factors and that's how we get to b but and here's the big but they do not equal c and i guess why why do they not equal c why are those at water factors first of all they're very very they appear to be very ev round numbers which you rounded up i want to point out um and and and you know but as it turns out there's more to actually uh be learnt about this and it has to do with the caloric availability in particular of two elements of food of protein and of fiber okay and i want to spend a little bit of time just unpicking on on i'm picking and picking this so protein let's deal with with protein now here's the interesting thing about protein a calorie of protein makes you feel fuller than a calorie of fat than a calorie of carb in that order okay one calorie okay so the question is why and in part this uh has to do with our understanding of what i call our food to poop tube our gastrointestinal tract now if i were doing this live i am doing this live but actually in in the theater i would now be able to wow you with my with my prop here which i always bring along and this ladies and gentlemen and i have the um i have the pattern and i'm very happy to send this to the people is a live-sized knitted human gut the human poop food to poop to so this is the mouth it's a very big mouth okay and then this is the esophagus and this collection of pillows here are are your organs so this is the stomach this is the pancreas this is the gallbladder the green bits the gallbladder and this this this is you this is your liver then after it comes through the stomach here is the small intestine but the small intestine is very long i am pulling this is going on forever okay can you see i'm just going at full speed until we get this is the appendix until we get to the large intestine and out the other side so all that is origami to us okay but we have to understand this because what happens is the longer something takes to digest and deal with within our uh within our gastrointestinal tract because of the different hormones that are released the fuller we feel okay that pretty much is a basic principle and both of this is going to be this is going to be true for both protein which is chemically the most complex of the three macronutrients protein fats and carbohydrates so it just takes time and energy in in order to in order to pull it off okay so therefore protein makes you feel fuller the second is fiber now fiber there's two types of fiber there is soluble fiber and there's unsoluble fiber soluble fiber is stuff like pectin the stuff that you you end up and solidifying um jelly or jam with and then there is unsoluble fiber and that is just fiber that we think about okay fiber and celery and in for that matter sweet corn and because it travels all the way down the gut and not the other side it actually also has the effect of making you of making you feel making you feel fuller okay so food that generally takes longer to digest makes you feel fuller so those are two protein and fiber okay for for these for these very very reasons and what happens is when your your the gastrointestinal tract your food to poop tube releases gut hormones we know of about 20 gut hormones 18 of them make you feel fuller and so these signals then as it works as food works down in your intestine they release these hormones it signals to your brain your brain then feels fuller it makes you it makes you corr eat correspondingly um correspondingly less okay and so this is broadly why from a digestive reason why um a reason why protein and fiber helps you make helps you you make yourself feel fuller it has to do with uh one part of its of its caloric uh caloric availability now that's the digestion element okay so now we're gonna have an interlude before i come to the metabolism element so let me give you an a then an interlude we've been talking about the heats of combustion so the amount of heat that it gives off within a within a bomb calorimeter have you given any thought about how much energy it takes to boil a kettle of water okay so what kettles are uk kettles are roughly one and a half liters 1.7 liters but we seldom fill them to the top so let's say a liter okay how much energy does it take to boil a liter of water now given that one calorie is a one degree celsius in one liter of water okay so therefore it must take a hundred calories to boil one liter of water and the moment you say it out loud you're going pardon me are you serious yes if you actually put it on a stove uh um put it on open flame if you actually click it you imagine wow it has a lot of energy going in there to boil the water because it takes time and everything a hundred calories now what is 100 calories so just to give you an example 100 calories is roughly the amount of calories in an egg okay a hens egg medium-sized hens egg 100 calories you're thinking all of that energy to boil the water and that's exactly right so imagine and we know that most of us eat at least two thousand calories a day two thousand maybe three thousand calories a day so if you do that math then two thousand calories is the is the amount of energy needed to get 20 liters of water from zero degrees from zero degrees celsius to 100 degrees celsius to boiling and keep in mind that this is the coming out of a tap it's not zero degrees celsius it's probably about 15 degrees so you don't actually need a lot of energy to in order to boil water you do but why aren't we boiling i guess it's the question how come we can have 2 000 calories of food and not boil given that we only carry five liters of blood in us five to five and a half liters of blood in us okay so now this is the interlude it's because of the way we metabolize our food and the way we harness energy from the food and we don't just burn it all okay because in effect what happens if you have a chunk of wood of charcoal of what have you and you burn it you're breaking the carbon bonds heat is given off okay that's where that's where the energy the vast majority of energy isn't i mean these carbon bonds you break them it gives off it gives of energy right and it gives off energy all at once because it's a bonfire okay like a bomb calorimeter this would not be a compatible with life so what we do is we our body manages to metabolize the food and then store the energy in reusable little units called atp okay now atp is adenosine triphosphate that's the adenosine group this is this this complex structure over here the key pit the key bits are these three phosphate groups the phosphate is a is a is a phosphorus oxygen o and h and these three and it takes a lot of energy it stores a lot of energy in this particular bond and so what happens consider atp a fully charged battery and adp adenosine diphosphate when you lose this phosphate group when it when when it gets cleaved off okay a puff of energy gets given off poof okay and that puff of energy is then enough for you to then do work all right this adp is then here again and then you then have energy that has been extracted from food and converts the adp by sticking a phosphate group back onto it to become atp again and this then and get gets recycled so atp is everywhere in our body everywhere it kind of moves in and moves out it's made in the mitochondria but it's everywhere in the body okay and every day this is recycled atp goes so it stores it and when you need it puff you need puff we go through our own body weight in atp every single day recycle atp adp atp adb now these are little molecules okay can you imagine how much 75 kilos actual kilos of atp is it's a lot and that is how we function right so we take the energy and we put them in the little atp things and only puff them out as as and when as in when we we need it and the process that that actually does this is called intermediary metabolism and i'm really sorry here for going into hard biochemistry and for those medics and biochemists out there this may trigger ptsd because because it did for me when i was thinking when i was thinking about it okay so intermediary metabolism is what we do to actually extract the energy from these nutrients the macronutrients of amino acids glucose and fatty acids because amino acids which is a breakdown of protein glucose which is a breakdown of starch and fatty acids which is a breakdown of fat are not they're not energy units they're not units of energy they're units of nutrients you then have to take the nutrients break the carbon bonds to release the energy to make the to to make the atp now here's the thing about protein and why protein is special okay so glucose and fatty acids they're organic molecules which means they're made of carbon hydrogen and oxygen and when we eat these um um when we eat these intermediate nutrients when they pass when we eat the foods and they're digested into nutrients and pass into our blood they're one of two fates that can occur depending on your feeding state you either store them and glucose is stored as glycogen uh until it's full otherwise it becomes fat fatty acids then becomes becomes fat okay now or you can burn it and you can burn it in this direction in order to make in order to make atp okay but glucose and fatty acids are only made of carbon hydrogen and oxygen and so they're interchangeable as long as you have the enzymes to do it protein there are a couple of interesting things about protein first of all we don't have a store of protein you might say well i have my muscles yeah but that's functional so the vast majority of our body aside from water is made of protein okay so all of the protein we eat is functional it's not a store fat is it is a story which releases the fat as you need it carbs but protein is functional it's either there to support you put you there repair organs okay or build if you're pumping iron if you don't use it it needs to be converted into fat okay so there's no there's no storage of protein protein has to be converted into fat in order to be stored as energy that the problem with protein it contains carbon hydrogen and oxygen but it also contains nitrogen okay and so what your body has to do before it can sort out uh before you can move the protein into fat it has to strip off the nitrogen it strips it off it converts it into it converts it into urea and then we wee it out okay this is why we have urea uric acid when we actually when we actually we it's all the nitrogen um that's been stripped off the protein so because of this a process of having to strip out the the nitrogen it takes work to handle protein that doesn't need to be there when you're dealing fatty acids and when you're dealing with fat and carbs and this work costs energy so for every 100 calories of protein that you eat every 100 calories of protein you eat you only ever absorb 70 calories 30 calories 30 percent of the protein you eat protein calories you eat are needed to handle protein and it's given off as heat okay so just by looking at the back of the pack the protein calories are 30 off already all right because because these are not the adwords the at water took into account a number of different things but he took into account the nitrogen but he never took into account the heat that that is required the energy required to actually pull off to actually pull off the the nitrogen and that in very many ways is why protein also makes uh it's more satiating than fats or carbs because fats and carbs well fat in particular is very energy dense it takes almost no heat between 90 is 98 percent to a nearly 100 available which means only a little bit off is given off as heat because fat is very efficient and is our primary fuel store carbohydrates well it depends if you're talking about sugar the white powdered stuff or if you're talking about a complex carb with fiber in it right and so if you're talking about sugar it's probably 95 96 percent available okay whereas if you're talking about complex carbs a slice of wholemeal toast for example then we're eating 90 available which means that for every 100 calories of wholemeal toast you're eating it costs 10 calories in order to sort the whole meal cos toaster okay caloric availability this is the the business the the um the energy required to the cost of doing business ladies and gentlemen right so how about now we think about so that's the concept of caloric availability when we actually deal with macronutrients but if you actually then begin to think about it you can begin to paint this concept of caloric availability over popular diets that that are actually there so i study um energy balance i study body weight now i think we've all seen this so this is otherwise known as the first law of thermodynamics meaning that we can't magic calories in from anywhere and we can't magic the calories away right so our body is going to be a balance between how much we eat and how much we burn because it's physics it's a fundamental law it's a how now there is a complexity and all the complexity lies in the why why do people behave differently around food why do some people respond to stress by eating other people respond to stress by not eating um that's what i study right the the the genetics of actually why people behave differently around food and so put simply some people find it more difficult to say no to food and eat more and so therefore the why influences the how which is the physics therefore we have people that have small medium and large okay so that that is a in a nutshell what what what i work on but in essence the only way to lose weight ladies and gentlemen okay is to create a caloric deficit is to absorb fewer calories than you burn that is how you're going to lose weight and so at the end of the day all diets including a number of fat diets that are out there which i'm going to deal with in a second that work manage to create a caloric deficit every single diet that works falls into three categories okay now they're not mutually exclusive because of you you can mix and match them okay there are their diets which are uh purposefully caloric in other words they say it on the side of things this is to eat less it's a caloric restriction diet i'll give you some examples in a second then there are diets that are high in protein and that they're diets that are high in fiber okay and i'm going to argue that all diets that work will find will will have at least one or two of these characteristics that that are here which is why which is the way they work so caloric restriction which i'm not going to talk about largely in this because this is it does what it says on a tin so you could have you could go on a low calorie diet these are so called lcds or very low calorie diets those are the shakes um and you know 800 calorie shakes and things like that and clearly you're going to lose weight weight watchers and slimfast so these are group support things which you can go and you you you measure food and you have sin foods and nonsense you're trying to eat less okay that's that this is the point and then there's intermittent fasting we can debate intermittent fasting about the additional metabolic benefits you may actually get from it okay and it is a debate but ultimately um the a primary reason why it works is because it creates a caloric restriction okay so these are caloric restriction diets let's put those aside for a second okay let's deal with the mother of all uh uh you know the big the popular diets that that exists these are the high protein diets but what is interesting oh okay hypo well first of all how high is high okay now as it turns out there is no industry standard but broadly speaking if you have more than 16 percent of your total calories at water calories okay from uh um from protein in your diet then this is considered a high protein a high protein diet okay so we typically are working on 14 to 15 typically so anything above 16 and um is considered a high protein a high protein diet um but the interesting thing about high protein diets is that the most popular ones don't even have the word protein in it they are low carb high fat diets hashtag lchf you could you go to instagram and and do it and you'll find millions upon millions of hits and these range anywhere from atkins which is what most of us would have heard of ducan southwest keto carnivore others exist but what i've done is i've picked the most popular ones and i've listed them in order of carbohydrate restriction the severity of carbohydrate restriction and so all of these diets in a in in effect uh have different amounts of evangelical uh uh they think their carbs are poisonous okay for for for lack of for lack of a better term and atkins all the way to carnival carnivore is obviously the most severe of all because all you eat all you eat is meat but what happens is when you remove carbohydrates of which for a typical diet are actually quite a high quite a high percentage of your of your diet you have to replace the calories with something else and people try and replace it with fat but fat per se is actually quite unpalatable so what you end up doing in addition to increasing the fat is actually increasing the amount of protein you eat so lchf primarily works for weight loss i'm not talking about glucose management okay for weight loss because it's high in protein protein is more satiating because of its caloric availability you feel fuller you eat less you lose weight okay now then there are hashtag lchf diets but with complicated backstories okay so they don't say they're lchf but they actually are gluten-free now look i realized that one percent of the human species are celiac allergic to gluten and so and so stay away from it there's probably another three to four percent of the world who are genuinely gluten intolerant and this ranges anywhere from being slightly farty to to severe intestinal distress by all means please stay away from gluten but up to 25 percent of us here will buy gluten free just as a product um um you know every every single day in fact so much so it's become a monetizable thing they're taken now foods that foods that never had gluten to begin with and label them gluten-free gluten-free rice rice does not have gluten it never had gluten it never will have gluten gluten-free water gluten-free shampoo google it i'm not i'm i'm i'm giving you the 4-1-1 here guys it's true all right for for that anyway but one is glue so gluten-free um and actually very very often is merged with grain-free so i'm not talking about the people who do it for glute for for celiac reasons very often people actually go fully grain free and when you actually do that it's actually quite a low carb diet and you increase the protein it's an lch of diet and then there's paleo okay now paleo this is where we're supposed to eat like cavemen because agriculture was bad for us and we have to eat like our paleolithic ancestors uh um greater than twelve thousand years ago um because this was the natural way of eating it we're not adapted to agriculture look there are a couple of problems with this argument this is it comes from the freddie flintstone the fred flintstone school of fantasia okay now i'm not gonna go this is not this is not a paleo talk but the paleo diet has a number of problems first of all it assumes one singular paleolithic people when this is clearly not true because what are you talking about the inuit uh you know on the on on in greenland are you talking about people on the savannah in africa are you talking about those hunter gatherers in the amazonian rainforest you're going to eat completely different things seal blubber or what or a whale or something like that and and maybe on the savannah you're going to be nearly vegetarian given how difficult it is going to be to actually to to actually track down track down a deer so first of all it's completely bonkers because there's not one single paleolithic person so what are you eating and secondly even if you wanted to eat like your freddy flintstone cousin the foods that we eat today are so heavily domesticated they do not resemble uh um you know anything of what we actually in the past so even if we wanted to we couldn't anyway the paleo that is high in protein that's my point i'm not trying to said that it's high in protein that's why people stick to it that's why people lose weight because grains were considered potato starchy vegetables were considered fruits of of agriculture these are all high in carbohydrates and so when you actually end refined sugars when you remove those you end up having a low carb diet that is why it actually works okay so if you actually look from a protein perspective okay and this is now just just i've now just put a little bit more detail in so the number of calories in the food pump calorimetry then you have calories lost through the feces then you have nitrogen loss through the wii and this gives you metabolizable energy so this is the energy that atwater calculated and is the side of the pack what i've now shown you is that with something like protein is that what atwater did not take into account was the heat given off during the metabolizing of protein which is called diet induced thermogenesis you know and then once you've actually done that which is like which is a great deal which is significant you then end up with net metabolizable energy so this is the energy which is not on the side of the packs but it's what we actually get out which we then use for our metabolism uh and our physical activity our exercises and just gen just general day-to-day living so how about fiber so so there was a there was a coder here for fiber before before i i close off here and for fiber well look um there are many diets which are very high in fiber so one of the things which i do okay my in my uh uh other job i moonlight sometimes as a presenter for the bbc and one of the programs i used to do was a program called trust me my doctor and um one of the producers one day came as a health program came in and said would i examine how healthy it is to be vegan so there are obviously going to be a number of complicated reasons why people choose to be vegan okay um this could be environmental um this could be ethical be animal welfare and and both are actually entirely legitimate reasons uh for choosing for choosing to be vegan but this was a health program and so we were trying to look at the health uh benefits um or not of of being vegan so the first question i i went so i i went i said okay i'll try it one month 29 days not that i was counting so the first thing is are vegan foods just automatically better for you i guess it's the first question and if you think about it just a little bit the answer is going to be no because i could have spent the 29 days eating chips and oreos and and no one would have claimed that was a healthy diet i haven't found this amazing product so these products here bacon rashes um classic snack blah blah blah okay here we go here here's the point so these are bacon rashers with no artificial flavorings or colorings but yet are entirely vegan what magical food is this anyway so i figure out what happened these are no artificial uh bacon flavorings or colorings so they probably use turmeric and smoked paprika or something like that my point is my point is this is hardly healthy food okay and i could have spent the entire time eating this so not being not wanting to be the guy that went on a vegan diet for 29 days and actually gained weight i decided to go on a plant-based diet now plant-based diet means that you don't eat a lot of refined sugars and in effect you eat foods as close to its whole of nature as possible so beans and pulses and grains and and that kind of thing all right so what were the schools gonna do after 29 days well after 29 days on a plant-based diet because i ended up being plant-based um i ended up losing four kilograms of of weight almost almost evenly my god i mean that's that's nearly 10 pounds 10 11 pounds my god i should start and i should i i should become a food guru i should be selling a diet but why did i lose weight and because i went plant-based the food was not calorically very dense okay meaning that it was very bulky you got to eat a lot of lentils to match the caloric density of a steak and you know lentils they look like flying sauces they're flying sources of shape coming in and they're flying sources the shape coming back out the other side you know there's a lot of things and there's only so much time in the day you have to chew right so anyway so what happens was even though i ate grossly in terms a lot of food in terms of just just weight i absorbed a lot less calories because of the caloric availability of the food because of the presence primarily of fiber fiber almost comes exclusively from plants okay so because i was having this plant-based diet i never had so much fiber in my entire life but i absorb less calories that is why i ended up losing weight okay so if you then look at this high fiber way of doing it to reduce the caloric availability of food so here are diets that are not necessarily plant-based but are high in fiber okay low gi glycemic index okay plant-based based up all the mediterranean diet for example which are which are um you know high in a lot of whole grains and stuff then you have plant-based diets effectively plant-based but with complicated backstories okay so you have the ridiculous alkaline diet okay now alkaline diet your blood ph is 7.4 so it's slightly alkaline and so people some people think that in order to maintain your healthy blood ph of alkali you have to eat alkaline foods two problems with this first of all it completely ignores the presence of your stomach which as i said at the beginning is ph 1.5 acidic so everything you eat has to go through the stomach it's acidified in order to begin the digestion process it then gets released into the small intestine where it's automatically neutralized okay it then goes back up to ph seven bang all foods we eat regardless of their starting ph ends up okay 1.5 and then ph 7 for our body to actually deal with it so that's the first thing so nothing we eat is going to change the ph of our blood secondly if you actually look at what is considered an alkali or or acidic food and alcohol so meat is considered acidic bad bad bad okay that's fine except that it's full of blood and so surely then it's alkali but we leave that alone okay then we have i don't know if you've seen for example okay people who are drinking their high ph water darling high ph water ph9 costs a lot of money but with a spritz of lemon juice in it why yeah i know just think about it for a second why because lemons are considered alkali and if you think about it for 2.2 nanoseconds you realize that first of all lemons and oranges and limes are citrus fruits so they're full of citric acid they also have loads of vitamin c which is ascorbic acid and so to to have the goal to call a lemon alkali just it makes no sense my point is because meat and dairy products are considered acidic and you have to eat alkali foods an alkaline diet is effectively a plant-based diet which is why people stick to it which is why people lose weight which is why it works then the newest kid on the block that i found anyway is the so-called cert food diet and the cert food diet is this um adele the singer okay she disappeared for a couple of years and suddenly reappeared i don't know was it a year two years ago half the woman she wanted she lost all this weight okay everyone was going oh my god she looks wonderful she looks oh my god she's more of a woman because she's less of a woman now you know and and she went on to serve through dad now if you actually google soap food dad and look it's a plant it's actually a very restrictive plant-based diet that is how adele lost her weight she ineffectively went on some mumbo-jumbo but that was actually a plum paste i'm not blaming adele adele's probably listening to a nutritionist um but in effect she was on a plant-based diet which is why she lost weight it's the same reason why i lost weight when i was a on a plant-based diet plant-based diet because it is high in fiber now all of this is fine okay because we've been talking about protein we've been talking about fiber but there is a and this in very many ways actually is a good that together with a lower amount of sugar but protein and fiber are key in terms of the quality of the food that you might actually be eating which is a problem with you know and this term has been doing the rounds recently on on tv and in the media ultra processed food so not processed foods processed foods is anything you bred as a cooking is a process so so any cooked food is a processed food um yogurt is a processed food ultra processed foods are industrialized processes in which you apply to a food that are that we do not do it is impossible for us to do domestically in our kitchen or in a normal restaurant okay under normal cooking methods you wouldn't be able to produce an ultra processed food they require uh they require um industrial processes now the problem with processing foods to that degree rather than cooking it or fermenting it or or you know or grinding it which is which are processes the problem with the ultra process uh industrialized way is that it does a number of things primarily it strips up protein and fiber okay so these foods tend to be lower in protein and fiber depending on whether it's designed a protein in it to begin with obviously but tend to be lower in protein and fiber okay and then the other thing is it tends to strip out flavor when you ultra process something which means you've got to add flavor back in where does flavor come from ladies and gentlemen sugar salt and fat okay the holy trinity of flavor sugar salt and fat you have to add it back in so the problem with ultra processed foods is that it is inherently lower in protein and fiber so very very calorically available very because as i said those are the two key elements that make a calorie that make a food less calorically available okay and higher in sugar salt and fat okay that is the problem with ultra processed foods not true for every single ultra processed foods but but across the board roughly speaking it is there the problem with using the not the problem the good thing about the ultra processed foods okay is because it's used you use industrial methods um they're cheap to produce and they're very long half la they're very long shelf lives either frozen or not okay so they're very cheap and as a result you know today certainly in this country uh uh 50 of our calories come from ultra processed foods okay that's i'm not kidding it's true okay but there is a big socio-economic divide okay if you take that 50 percent and actually then map it across socioeconomic class the poorer you are the more likely you are to have ultra-processed foods now the y's are going to be complex but part of the reason is because these are calories which are very very cheap okay in other words therefore you know anywhere you can probably get close to 900 calories depending on what you're buying for something like a pound okay there are a lot of calories now imagine if you're mrs smith okay now look everyone here i'm generalizing but most of you guys listening to me here tonight are gonna be like me painfully middle class okay we are i'm sorry i'm gonna say it i'm painfully middle class we are not underprivileged human beings certainly not we're not i'm not saying we're rich but i'm saying that way what are you gonna have a tea for for dinner when you're done you know what you're gonna have for dinner and even if you didn't you're not gonna be concerned about it because you could call deliveroo or ubereats or or make something okay you're not gonna be worried about it but if anything this pandemic has shown us take the marcus rashford uh push for free school meals for for kids is that there is a scarily large percentage of the population in the uk the sixth richest country in the world who are food insecure okay who are not starving you know uh um in a famine type of state but who are food insecure okay so when mrs smith comes home okay and she has she has to have two jobs two minimum wage jobs in order to keep the family okay so therefore she has no time because she's gonna work two jobs okay and she has to buy 299 for four pizzas from iceland or wherever to feed our kids who are we to judge right and this is the problem who are we the judge when when they then have um ultra-processed foods and i think this is just a new one i thought it was important for me to end with this because i can end with this saying that well let's eat more protein that's even more fiber and this is all true but how do we then apply that more equitably so that we can improve the health of the dyes to everyone and i think it's use i think it's unhelpful to say please replace replace your chocolate bar with a banana look sometimes life demands a chocolate bar sometimes life demands a banana the question is can you make a healthier chocolate bar okay and i think that is the the question we got you're never gonna make a chocolate bar healthy but can you make a healthier chocolate bar okay so um a couple of last thoughts so guys i we cannot fear food okay is it true that the vast majority of diet-related illnesses today um are are sorry is it true that the vast majority of non-infectious diseases that we're facing today we're clearly in the middle of an infectious disease pandemic is it true that non-infectious disease is diet related it is okay obesity type 2 diabetes high blood pressure so we need to fix our diet but we don't we shouldn't do this by fearing food and fearing food this is gwyneth paltrow's goop i don't want to drive clicks but there we go which is and she's trying to sell your leanest livable weight that's like how to stay as skinny as possible without dying as far as i can check and by the way i gave a another talk but i wrote raised this point at the new scientist live before the whole shooting man shut down to the end of 2019 oh those halcyon days um and the mayor and journalists picked it up so this picture i i took from the um from the independent which is spliced together thinking that you know i had some beef you know gwyneth paltrow uh and cambridge geneticist has a b dude i've never met gwyneth paltrow anyway this is fearing food what we what have i spent the last 45 minutes talking to you about understanding food what is it made of how does our body deal with it i love food ladies and gentlemen i love food we need to love our food more understand our food more just eat a little bit less of it so why don't calories count here are some important points we eat food not blinking calories all right we eat food and our body then extracts the calories from the food and take that takes energy that takes effort that takes time okay which is why we talk about the quality of food and not the calories we focus too much on weight we have to focus we have some of us have to lose weight but we need to focus more on our health and then your weight will then take care of of itself so look this is the book okay why calories don't count i appreciate it if you if you if you're interested and and want to find out more on you you know to to go and have a have a look at it so what should we count instead of calories this is i'm almost giving you the uh the punch line at the end here um i think we need to worry about our protein amount but there is a sweet spot okay 16 when i say protein don't think steaks automatically it can include steaks but i'm talking about beans pulses tofu okay any source of protein fish fiber we in the west eat something like 15 to 16 grams of fiber a day we need at least 30. more the merrier we don't need anywhere close to the amount of fiber we actually we actually need free sugars okay so these are the sugars that are added which involves the powdered stuff or algal nectar or honey uh um you know anything you add rather than actually stuck within the fruit we need to try and limit to less than five percent of our energy intake a day okay and we need to consider really ladies and gentlemen some meat three days look i'm not countenancing everyone becomes vegan clearly that's not what i'm doing okay we don't need all the world to become vegan we need a lot of people in the high income countries to reduce their meat intake by 10 to 20 percent so listen ladies and gentlemen it's been a deep pleasure to to to speak to you i have left i went longer on than i i intended i'm ever so sorry but um i am very very happy to do the q a now so i'm going to stop sharing that i'm going to stop sharing that and i'm back to here thank you [Applause] you

Channel: The Royal Institution

Views: 809,268

Keywords: Ri, Royal Institution, weight loss, giles yeo, diet, calories in calories out, cico, calories, calorie counting, dietiacian, science of weight loss, bad diet, genetics, genetic predisposition, obesity, healthy weight, dieting, nutrition

Id: GQJ0Z0DRumg

Length: 49min 22sec (2962 seconds)

Published: Fri Aug 13 2021

Reddit Comments

[u/Scrap_Iron_]

Calories count. I haven't watched this and I expect it to be the dumbest facebook mom science I've ever heard. Here we go...

[u/SolemnSwearWord]

Thought it was a good post and an informative video. Thanks for sharing.