Is Exercise or Nutrition More Important for Weight Loss? | ZOE Science and Nutrition Podcast

[Music] welcome to zoe science and nutrition where world leading scientists explain how their research can improve your health we've all heard the message exercise is important we should all go to the gym more often if we want to lose weight we need to exercise but how much of this is true in the context of human history our transformation into couch potatoes happened in the blink of an eye our hunter-gatherer ancestors needed to venture out daily to find new sources of food only 100 years ago most people relied on manual work to make their living today things are different many of us live our lives in front of a screen online shopping and remote work means some of us don't need to leave the house at all so how bad is this for us the answer is now clear low levels of physical activity leads to increased risk of disease and a lower quality of life in older age however when we come to the question of what sort of exercise you should be doing how often and how much it contributes to weight loss the answers might surprise you the fitness industry like the diet industry seems to present a brand new trend every month so in today's episode we'll find out what the latest science says answering questions like how important is exercise for weight loss can fasting make exercise better for our health and how much exercise do we really need to do to see the benefits to answer these questions and more i'm joined by dr javier gonzalez associate professor of human physiology at the university of bath whose research is focused on understanding the interactions between diet and exercise and how this impacts human health and disease javier is also a technical advisor to the athletes in the ineos tour de france cycling team javier thank you for joining me today so why don't we start with a quickfire round of questions from our listeners uh maybe just a yes a no or you know one sentence asks answer if you can and then i'm sure we'll go into some of this in in some more detail so let's start with is exercise the most important thing for weight loss for most people no okay interesting does a walk count as exercise it depends on how you define exercise but again for most people yes if you're working out do you need to eat lots of protein powder no does too much cardio stop you from burning fat no is exercise important during menopause yes an exercise i would argue is always important fantastic uh i love this question that we got on uh on instagram uh is yoga effective for weight loss probably not as effective as other forms of exercise but it does have other benefits okay brilliant we should come back to that and a related question do you need to be doing both weight lifting and cardio to get benefits from exercise to get all of the potential benefits that exercise can offer then the answer is probably yes okay and last question do men and women respond to exercise in the same way no um but there's plenty more as well that influences that response that i'm sure we can get into brilliant all right well i think there will be quite a few answers there that will surprise many of our listeners and one or two that that surprised me um but why don't we start at the beginning and then we'll sort of dig into all of this in in more detail you know javier why does exercise matter for health at all so exercise is crucial for health probably because we evolved in a environment where we needed to have a high level of physical activity and nowadays of course most of us or a lot of us have jobs that are desk based and our lives are relatively sedentary we end up doing less leisure time activity quite often as well and so we're not well adapted to that environment that we're living in nowadays an exercise has a number of benefits it seems to affect almost every single tissue in the body we commonly think of it improving perhaps our heart health also our musculoskeletal health the health of our muscles and our bones but it seems like it even affects things like our fat tissue and our brains and all almost every single tissue in the body is affected by exercise and so how much exercise does you know someone listening to this how much exercise do you need to do to start to get those those health benefits you're talking about yeah the government guidance would be something like it depends on which country but at least in the uk the government guidance is to do at least 150 minutes a week of moderate intensity exercise or 75 minutes per week of vigorous intensity exercise plus two strength sessions now that's an okay starting point for the general population um but the everything counts so as little as ten minute bouts of any form of physical activity can start to accrue benefits and the general advice is the more the better so a very rough guide and i'm sure different people will respond differently to exercise and some may enjoy certain forms of exercise so in that scenario i think the the simplest advice would be do what you like and do as much of it as you enjoy doing and is there a a minimum amount at which this sort of starts so you know if i just walk round the block really slowly you know is that exercise what about if i go for a really long walk and it's you know quite tiring you know is that exercise where does this where does that start because those words you describe moderate exercise like what is that actually what does it mean have you yeah it's a great question because actually we should probably define what exercise is in terms of how that relates to physical activity so physical activity encompasses every bodily movement that we make that increases the amount of energy we're burning and it doesn't actually have to include movement so that's the textbook definition i actually prefer the definition of muscle force production and the reason i prefer that is because if you're sitting at your desk right now the muscles around your torso are stabilizing that torso your spine and everything and that's got an energy cost to it so you're expending more energy sitting upright than you would be lying down on the bed and so that's already a form of physical activity or at least an increase in energy expenditure so any any muscle force production any time your muscles are contracting you're burning a bit more energy and that contributes to overall physical activity so i i'm working out right now while sitting on my ass is that what you're telling me heavy i like exactly at the very lightest level but yeah you can feel good about yourself i'm guessing that's not enough though to meet the criteria you were describing no no and where exercise comes in is it's a bit of a funny definition because it really depends on your motivation so if you go for a walk and that walk is part of a task like you are walking to the shops then it might not count as exercise but if the intended purpose of your walk is to improve your health or fitness then it comes under the definition of exercise so i actually prefer the term physical activity to exercise because scientifically that's what physiologically that's what we're really interested in it's all of the energy expenditure and when we're talking about moderate intensity physical activity then it's activities like brisk walking starting to get your heart rate slightly elevated and but still able to hold a conversation when we get into vigorous intensity that's where you start to not be able to put a full sentence together without taking a breath got it um so that's like when i when i walk with my friends who are much taller than me and i'm just trying to keep up that's that's it and so how long let's talk about that sort of like i like the idea of a brisk walk because it comes up actually in quite a few of these it actually that is the first level that might really make a difference to your health right which is a lower i think a much lower bar than many people expect which is well if i'm not going into the gym pumping iron like none of this this counts what is the amount of um sort of brisk walk like for how long would you need to do that to start to get some of the health benefits that you were talking about with um with physical exercise yeah you can start to see some quite profound benefits actually with as little as 30 minutes of brisk walking per day and that doesn't have to be all in one go so you can split that up into five or ten minute bouts across the day and accumulate it over the day that can actually improve start to improve things like your your blood lipid levels levels of fat in the blood so that's pretty amazing so you're saying that 30 minutes a day of brisk walk actually can make a profound difference to like measurable markers in our blood and that we can do that we don't even have to do it all at once you're actually saying you know i can cheat and do that in three or four different pieces exactly exactly i think that's you know that sounds uh you know quite counter to what i think many of us would imagine um let me come on to the related question that you know a lot of people were asking us to to discuss before this which is this idea of cardio versus sort of strength training or weightlifting and firstly could just explain what those things are because they're words that we hear and i think many of us aren't really clear exactly what they mean and then explain like why is there this difference and does it matter for for people thinking about this for their health and probably their weight as well yeah sure so when we're talking about cardio i guess most of the time we're talking about well at least in the scientific area we would probably call it endurance exercise but i guess the term cardio comes from the idea that most of the adaptations you get are in the cardiovascular system and these are things right from the lowest intensity of brisk walking through to running cycling swimming and that kind of thing where you might do an exercise session that lasts for 30 minutes up to an hour you get some athletes doing very long training sessions of four or five hours of this type of exercise then strength training might be doing weights in the gym where you are lifting weights maybe from five to ten repetitions and repeating that in sets it doesn't have to necessarily be lifting weights strength training does also include body weight exercises so it could be things like squats um so body weight squats things like press-ups and pull-ups but even actually for for people who are slightly advanced in age even just getting up and down from a chair a number of times can be a form of strength training that can help improve their their capacity for daily living really and what's the difference because you talked about the time but why you know why is what's going on physiologically that differentiates these and and then can you explain a bit you know what impact that has and and why it matters sure so the they are they do sit on a spectrum so you can get areas that slightly overlap and you can think you can probably envisage that if you think of something like cycling up a hill a very steep hill there's a point where that probably turns into more of a strength workout on your legs than it does a cardio workout so the the force of you putting pressing down on the pedals crosses over into that strength workout and flip it the other way around where you might be doing a circuit class in in a gym session you might be using weights but it's relatively light weights and you're lifting a lot of reps and that can transition into a cardio workout however if we go to the extremes of cardio versus strength then they do have quite different adaptations and that's why the advice would be that to get all of the health benefits of exercise it's good to do both cardio and strength work and the cardio exercise will improve things like your cardiovascular system so your heart will can get stronger your blood vessels become more compliant or more elastic if you like so they can help lower your blood pressure whereas with strength training you get a number of other adaptations so your muscles clearly can get stronger but even your ligaments and tendons can get stronger and i guess one of the things that people often don't think about is is bone health and heavy strength training can improve your bone mineral density and so improve the strength of your bones also well i think maybe just to talk about that second bit this is one of the reasons why strength training is not just for people who are like in their 20s and want to look amazing on instagram right this is actually there's real health linkages could you talk for a minute more about that because i think often we think about strength training perhaps has been very much about sort of the body beautiful uh but there's more to it right ah absolutely um so our strength will typically peak when we're about 30 to 35 um maybe 40 for some of us if we're lucky and then it will gradually decline after that point almost no matter what we do however by doing strength training we can slow that decline and the aim is that there'll be a certain point where we we gradually just become weaker as we get older and there'll be a point where even getting out of a chair or lifting the shopping bags is now becoming too difficult we're not strong enough to do that and so the idea is if we can maintain strength training we can delay the point at which getting out of a chair is now impossible to do alone so it becomes really important for healthy aging not only from that strength standpoint but also then the the bone health so if we do have a fall then we're less likely to fracture the bone because the bone has a greater bone mineral density got it and what's going on between these two so there's obviously stuff going on sort of like at a at a very you know physiological level which is quite different between this cardio exercise which you talked about going on for a long time and you know this sort of strength training where i'm just doing this in a very short period of time can you help us understand a little bit more about what's going on how that ties i guess to like our energy system because i think that's going to start to bring us through to nutrition which obviously we're um we're very interested here here at zoe yeah sure so it's probably worth starting with strength training so things that are very short duration they're almost like mini bouts of exercise and the energy we use there can then extend to the longer duration exercise so with with strength training when you initially do a very high intensity movement let's say you lift a weight with your bicep the main energy system you're probably using there is something called the the phospho-creatine system and that's commonly why people who lift a lot of weight sometimes supplement with creatine because that can increase the creatine stores in the muscle and that can help that energy system so they can do more repetitions without fatiguing but that doesn't really use the the fuels in the same way that longer duration exercise does so when you increase to longer duration exercise one of the benefits of cardio is that you're burning through energy and the main fuels that we use there are carbohydrates and fats so the one of the other differences between cardio and strength training is that with cardio we're going to be burning through total energy more than strength training on the whole and we're going to be burning through our carbohydrate and fat stores in addition to that we get a high heart rate that's maintained over a long period of time there's greater blood flow through all of the the circulatory system and that's why we get those adaptations in in blood vessels as well because they our body sort of has to improve the way in which it can get this energy to these muscles that are working away exactly that yeah so i think it's a brilliant transition to uh you know i think one of the biggest questions that um uh we all ask which is you know if you're thinking about weight loss which is i think for for many of us who are sitting at our desks all day not adapted you know in the way that you described earlier you know is exercise uh or nutrition more important so if you were to ask me weight maintenance i would answer very differently for weight loss for most people diet is almost certainly more important than exercise and i guess just to validate that um for most people it's a lot easier to eat energy than it is to burn energy so um as an example a typical one-hour gym session for an average person might be about 400 maybe 500 kilocalories of energy now my bowl of porridge in the morning or oatmeal is easily over 500 kilocalories of energy and so in us in a small bowl you can easily overeat what you may have just burnt in the gym now we should also remember that our resting metabolic rate is constantly going on so we're constantly burning a baseline level of energy so we shouldn't try to always offset what we burn through exercise but clearly exercise doesn't make a big dent in our energy budget compared to how easy it is to eat those calories now it is very different with elite athletes that we can maybe come on to later but for the for the vast majority of people that's the general finding that which i think is really interesting right and it's it's quite counter to i think a lot of um the messaging that we've heard over the last 30 or 40 years you know some of which i think comes from you know very large food companies that have a particular angle to uh to deliver there where you know i think the story we're told is you know what everything to do with weight is because people aren't doing enough exercise and you know if only people were doing more exercise it'd be fine and therefore you know it's fine to sell uh you know sugary drinks in schools is my favorite example of this to kids you know as long as there's a playground because after all they could just go and and burn this off um and i think what you're saying is obviously exercise is really important but you can't just go and do a bit of exercise to burn off sort of eating all of this uh you know incredibly uh poor quality food that um you know we're all surrounded by now in in the developed world exactly i guess i guess the way i would frame it is probably the exercise has a number of benefits but we shouldn't expect that just by beginning exercise we will lose weight um it can actually help control appetite and it can help with things like body composition but that's when in conjunction with with diet so really yeah diet comes first but exercise can really help us achieve the goals that diet is achieving as well now you're doing some really fascinating research actually about interaction between uh fasting and exercise right which also i think really challenges this idea that you know a calorie is is just a calorie and that a good diet is about you know making sure that the number of calories in equals the calories out can you tell us a bit about um you know this research that you've been doing and and and what it tells us yeah sure so we've done a series of studies now and we're we're continuing this line of work um and with the short-term studies where we study people for about 24 hours we might ask them to skip breakfast or eat breakfast and exercise or rest and we tend to find that when they skip breakfast and exercise they burn more fat during that bout of exercise and that's that's been known for quite a long time we tend to burn about 20 percent more fat when we're fasted in that overnight fasted state compared to say an oatmeal based breakfast um our work tried to understand then if that continues over a full training program because what we would see in a 24-hour period might be very different over a six or 12-week time frame so one of my former phd students ran a pretty intense study where he fully supervised every single exercise session um he recruited 30 men to complete this six-week training program and he measured the amount of fat and carbohydrate they were burning every 15 minutes of every single training session over a full six weeks and we did see with the very first session the group who were performing that exercise in a fasted state were burning up almost double the amount of fat actually in this study compared to those who were performing the exercise in a fed state and that those lines were parallel throughout the six weeks of training so as as people became fitter they were all burning more fats but the group who were in the fasted state were still burning more fat at the end of the training program than the group in the fed state now the this links into that idea that it's more than just calories because we did actually give both groups the same number of total calories before and after the session so the only difference was the timing in which they consume those calories so whilst one group was burning more fat both groups had the same energy balance and so they had the same weight loss throughout the whole study so for weight loss it seems to be more about energy balance than it does to be about fat burning or fat use but for other health outcomes that's where it became really interesting so we found that the people who were burning more fats actually improved things like their glucose control and their insulin sensitivity to a greater extent than the group who had breakfast before exercise and weren't burning through their fat stores so so what you're saying is actually they were getting the same number of calories but some of these people were exercising fasting and somehow this was this was changing the way their body was working and you were seeing these you know like measurable and sort of clinically important improvements um in these health markets that you would expect to you know have an impact on on their long-term health because their body was getting better at burning fat than burning carbohydrates burning blood sugar is that the right way to understand it yeah yeah we think it's something to do with um the turnover of fat stores within probably within muscle so um you could if you think of our fat stores we store most of our fat in fat tissue but we also have these small fat droplets within our muscle an important fuel store within the muscle but what we find is in people who are sedentary these pools of fat in their muscle you can almost think of them as stagnant pools and you get buildup of toxic metabolites and they seem to interfere with the muscle's ability to respond to insulin and to take up glucose out of the circulation take up sugar out of bloodstream and what we think is going on here is that by performing exercise in a fasted state you burn those pools in the muscle they're turning over more quickly they're not a stagnant you don't get that buildup of toxic metabolites and so the muscle is is healthier it can take up more sugar out of the bloodstream more effectively and so does that mean we should all be doing all of our exercise in a fasted state does it just mean that you know when i take my daughter to school and push her for 30 minutes it feels like a brisk walk she's getting heavier then uh at least i should do that before i have breakfast how do i how do i think about applying this and how should our listeners think about applying that to their um to their lives yeah it definitely depends on what your particular goal is and might even depend on on you as an individual so i should caveat that we have only currently run this study in men in middle age men and we are keen we've actually got plans to do this study in a wider population including women as well um but the other thing to consider is is what your your goal is so if for example you want to do an important session you want to work hard in your session or as hard as possible then actually having a breakfast is a good thing because your performance will be impaired if you haven't had a breakfast and that's even if your exercise session is in the evening so there have been studies where people either ate or skipped breakfast in the morning they all had lunch at lunch time but their performance in the evening was still impaired when they had skipped breakfast in the morning so my my advice for somewhat for the kind of average person would actually be to to mix it up so to perhaps do two or three sessions a week where you might perform them in a fasted state and other sessions in a fed state and no so everything everything in biology and physiology is about trade-offs there are actually potential downsides to performing exercise in a fasted state as well and if i'm listening to this and i'm i'm not only thinking about health improvements which is obviously incredibly important but i'm also thinking about weight loss um how do i understand that because you said hey i'm now burning fat people like well that's good i want to burn some fat um but then you also said actually because what you actually saw was not a change in um weight loss between these groups because you fed them exactly the same amount of food which is a bit artificial i guess compared to what they might do naturally how would how do people think about this for weight loss do you do you have the data yet or is that also part of the the future studies yeah that's that's part of our future studies from our short term studies it seems like if you don't force people to eat what they had skipped before exercise then actually over 24 hours they don't fully compensate for having done their exercise in a fasted state and so if that continues over the long term then they may lose more weight um but yeah i'd be very hesitant to say that because we know that longer term effects of exercise on appetite are very different to the short term so we hope to have that answer in in a year or two's time well we'll be excited to to talk about it and and as you know this is an area we're really interested in in helping to to support as well so i think the playback here i think is doing some exercise in a fasted state can be really beneficial for health then i'm hearing you say potentially also you know from what you've seen supported for weight loss but that that is not really proven by the data yet because as we know you know you can do these 24-hour studies and then you translate that into you know three months and suddenly you know these effects get get balanced out which is part of why this science around everything to do with nutrition and exercise is so complicated right yeah absolutely and i think it's probably worth just mentioning as well if people are going to try this exercise in a fasted state especially people who are perhaps concerned over their bone health it might be worth taking some calcium before those sessions um because one one of the downsides to that type of exercise is we it's probably a catabolic state for the bone javier what does that mean so the bone is in a state of breakdown okay doesn't sound good uh no and it's probably because when we exercise we sweat stress out salts as we we might be aware of but we also actually sweat out calcium as well um but it has been shown that taking some calcium before a bout of exercise in a fasted state can help prevent some of that bone breakdown so for certain populations i i would advise taking some calcium before those sessions to try and prevent that and if i'm doing a brisk walk am i worrying about that even or is that more like a more energetic activity where then you'll describe than that yeah you're probably okay with a brisk walk but this is it's probably more relevant for athletes doing this type of training more vigorously yeah and and i think bringing up professional athletes i think is a great way to talk about um your work with i think some of the most amazing athletes in the world right professional cyclists uh and i know that you work with the uh the ineos uh tour de france team uh they seem like almost a different species uh of person than uh than i am um is there anything that is that you do there that you think is relevant for ordinary people listening to this call and indeed also what is almost what is really different so how do we learn from this um for uh for those of us who are not these um these super athletes yeah i think you're absolutely right they they are completely different species in many ways um there are some things we can certainly learn from them and actually the the idea of performing exercise in a fasted state really stems from from professional sports running and cycling in particular where these athletes would do exercise sessions not just in a fasted state but they would train twice a day so their first session would really deplete their carbohydrate stores they would then eat low carbohydrate at lunch and maybe do another session in the afternoon and so they're really pushing the limit on on they're almost taking that fasted exercise to the next level and the idea behind that is that one of the stimuli to adapt to exercise is a low glycogen concentration in muscle and what that is is it's our storage form of carbohydrate so when we store carbohydrate in our muscle it's in this form of glycogen so so javier because we talk a lot about blood sugar right so when we eat carbohydrate uh you know like rice or bread or coca-cola or whatever right it turns into this blood sugar you just help us to understand them so how does that how does a glycogen fit with with that sure so the the blood sugar or glucose in the blood um will be taken up by muscle um during exercise that that happens independent from the hormone insulin but when we're at rest we have a meal we get an insulin response and that insulin will help drive that sugar into the muscle once it's into the muscle it has two fates if you like one will either be it'll be burned as a fuel and the other will be that it'll be converted into glycogen so that's where it's stored in its kind of fuel tank if you like within the muscle got it and you said there's a limited amount of this that's in in the muscle could you explain that for a minute because and that ties in i guess to what you're describing with these these super athletes sure so whereas our fat stores are for all intents and purposes limitless we could just run for days and days and days on our fat stores our glycogen stores will run out very quickly and it's actually why people often turn it hitting the wall during the marathon where after about 90 minutes or so of a vigorous intensity exercise those glycogen stores will be pretty much completely depleted i think i i think i hit the wall quite a bit sooner have you but yes so it yeah it will run out very very quickly and when that glycogen is low that seems to be a signal that starts a cascade of events in muscle that stimulates some adaptations and so the kind of idea behind training in this depleted state was that you're ramping up the volume on that signal to adapt and so it really stemmed from professional athletes and it's now starting to filter into the health area got it so these people you know they're saying i'm using up all of that glycogen i'm continuing to exercise um hard so i've got to find other ways to to create energy and that's not only blood they can't just be the blood sugar you're saying because they're intentionally not eating meals with you know they're not drinking sort of sugary drinks to keep this going so they're presumably having to to get to burn burn fat is that what they end up having to do yes exactly yeah so they're burning fat in that state and and the downside to burning fat as a fuel is that it's a relatively slow burning fuel so you can think of it as as kind of a diesel fuel whereas our carbohydrates are a petrol and so you do have to lower the exercise intensity when you're burning fat as a fuel so it's more the kind of low intensity endurance sessions that they might do this type of work with and you're creating sort of flexibility then are you like i've got this ability to run on both these these fuels and it's and that that's that's a good thing is it that's the ultimate goal yeah because um especially athletes they do need to be able to burn fat as a fuel when appropriate so at those low intensities but they still need to be able to burn carbohydrate if you as a fuel when it's when the race really gets going they need to sprint up a hill or sprint to the finish line that's a carbohydrate-dependent activity and it's where different modes of training and nutrition can really adapt that metabolic flexibility some aspects some strategies that have been used in the past influence one of those but you lose the flexibility of the other so one example of that is actually low carbohydrate high fat diets when they're eaten chronically in the longer term then you do increase the ability to burn fat as a fuel very effectively but it seems like the ability to burn carbohydrate as a fuel is down regulated even once your glycogen stores are full again so even though you've got that carbohydrate in the muscle you're not able to use it your body has adapted to using fats all of the enzymes for carbohydrate are down regulated and so you just can't tap into that that energy when you need to do we know about how gut health fits into any of these discussions around exercise you know have there been any studies that look at these links and um you know is there anything you can share with us there yeah i think it's a really exciting area uh i think we we don't know very much about it at the moment what what we do know is that if you just compare athletes with non-athletes then they do have very different gut microbiome profiles um it's difficult to disentangle whether that is an effective exercise or an effective diet because most athletes are burning a lot of energy and eating a lot of energy so the total volume of food is very high but also the composition tends to differ as well from non-athletes so it might be higher protein potentially higher carbohydrate as well and because of that higher volume of food they're probably also getting more total fiber more prebiotics as well and so there's a number of reasons that could account for differences in the gut microbiome between athletes and non-athletes i think the next step would really be to do randomized controlled trials of exercise to see how that directly affects the gut microbiome um ideally with and without weight loss so you can then disentangle the effects of exercise from weight loss whenever we're we're thinking about exercise then i think we get a lot of questions about what should we eat sort of before during and after exercise and um i think there's a lot of myths here right uh you already answered right at the beginning like uh do i need to have a protein shake uh if i'm doing exercise and i think you gave a pretty strong no so um could you tell us a bit about like what are the facts about sort of the requirements um and we don't always believe a lot about this idea of sort of macronutrients in zoe because it's very um you know there's so many different sorts of foods but help us to understand like what's the um what are the realities of this yeah well one of the main roles of protein or one of the reasons for taking protein or at least eating protein in conjunction with exercise is is to facilitate muscle reconditioning and what i mean by that is is the adaptation of muscle so muscle is mainly comprised of protein and we often think of the contractile protein so the part of the muscle that produces force the part that gives it the size and the bulk that you see in a bodybuilder but actually the proteins are also involved in the enzymes within muscle the mitochondria within muscle which are the the kind of powerhouses of the muscle that produce the energy for cardio exercise and so protein is important in remodeling all of those different aspects of of muscle so whilst i i stand by the point that you don't need protein powders protein itself is certainly important for both people who exercise and people who don't exercise the reason i said no to protein powders is because you can achieve the same goal with dietary food sources of protein and in many ways they can actually be more effective than certain protein powders so just to kind of validate that um if you compare for example um a control condition where they might not have any protein at all versus a soy-based protein versus whey then what you tend to find over a training program same amount of training that people will gain more muscle mass with the whey versus the soy and more muscle mass with the soy versus nothing but what's really interesting is they had a fourth condition in this particular study that i'm referring to and it was milk so just plain milk and it performed just as effectively as whey protein amazing so you don't have to eat something super artificial you could just and i'm not suggesting everyone should eat milk because there's a big variation we see in response but that's sort of quite amazing and how much protein do you need because i think this is also an area where you know you can't anywhere you go on like the grocery stores or anything now here's this ultra process bar with a big label on it saying like high in protein which obviously makes me think oh well that's good i i have that and i have you know heard people say oh you must eat um you know some vast amount of protein within 30 seconds of doing exercise or all that hard work is wasted which i think if you're like me and you don't really love exercise you know you're doing it because it's important for your health it's like oh my god i'm gonna have wasted all that hard work if i don't get this protein in 30 seconds like i've always been a bit skeptical but what's that i bet there's real data on this heavier how do we uh how do we think about that yeah so i guess before i tackle the the dose point i'll just have the timing point where um it's it's one of those things where there's a grain of truth but it's taken completely out of proportion where immediately after exercise we are more sensitized to protein and so if for example you have a pint of milk which has about 20 grams of protein in um in the hours after exercise more of that protein will be incorporated into your muscle than it would do if you hadn't exercised and it's it's still a relatively small amount so of that 20 grams it tends to be about 2 grams have been incorporated so about 10 um so exercise does sensitize the muscle but that that doesn't completely drop away within 30 minutes it just gradually comes down over about 48 hours so even 24 hours after exercise your muscle is still sensitized to protein intake more than it would be if you hadn't exercised it's just slightly less than it would have done immediately after exercise so rather than a window it's just a gradual decline in that sensitivity over a full 48 hours and so if i'm thinking you know i'm a listener i'm listening to this um does that mean i should be worrying about this or actually if i'm eating a good balanced meal with like plenty of plants which we know have lots of different protein in them and other you know actually and i'm not a super cyclist right i'm this is just i'm really am i going to get everything i need or is this something i need to um adjust to to sort of compensate for yeah if if you're eating three or more meals a day you're probably eating in close enough proximity to your last exercise about that you're getting a benefit so you probably don't have to worry about it if you are not if you're going to have exercise and not eat for 10 hours then yeah you probably want to to fit some protein in between got it so if you're doing sort of quite very time restricted eating for example i guess that would be a good example of one of the sort of sustainable dietary patterns then potentially thinking about how exercise fits with with with that time window is something that is that and how and given what you're saying it sounds like you would you you're saying you don't want it 12 hours away from um from when you eat equally well it sounds like sometimes you might want to do the exercise before you eat and other times you might want to be doing this you know you know shortly afterwards etc exactly and there may actually be a case here for there might be some scenarios i'm not completely against supplements for example i think they have a place and it's it might be here where um someone might be performing time feeding or intermittent fasting and not want to eat a lot of calories and a supplemental form of protein can then provide the protein without many calories and so there's probably a scenario there where they can be useful and i think the other scenario is is for convenience as well so um yeah i'm not completely against them i just think you can achieve most of the goals almost all of the goals um with real food brilliant and uh you know i think often the the challenge is you can have a a window thinking just about the exercise but when you step back and look at the overall health impact right then we know um so much now about the uh the importance of the quality of overall food so i think figuring that out is interesting now i have a question here which is actually the reverse of this so you know how do i best fall for uh for endurance exercise so if i am having if i am doing some of this extreme exercise that we're talking about um how does that change um this advice if at all yeah and it this would definitely depend on the level of the athletes here so um for if you take the tour de france cyclists what you see in their diet would be [Music] viewed as pretty horrendous by most people in terms of the amount of sugar for example that's in it because they are burning through so much energy and sugar is such a good fuel for high intensity prolonged exercise that the amount of sugar tour de france athletes get through is is actually incredible so some of the reports in some studies have been up to half a kilo a day wow of pure sugar which is incredible which i imagine you're you're not telling us to uh to copy at home kids is that is that right absolutely not this is one scenario where they we treat them as a different species because they can burn in an hour they can burn through almost 2 000 kilocalories of energy whereas your average person might be burning through 400 so it's just a completely different ballpark i'm guessing that all these muscles i'm using right now to keep my body upright while talking to you is not getting me to the uh 2000 uh calorie output unfortunately okay that's really helpful advice um so one of the things we touched on at the beginning and which i'd really like to sort of talk about here at the end is around personalization and differences and i think you already said that you see differences between um men and women but that there were also other differences would you mind talking a bit more about that i think both in general and then i think we'd love uh to talk a bit more specifically one of these big changes that um that we see with women is obviously sort of before menopause perimenopause after menopause um and so i guess you know what does the science say um and how should people think about that depending upon you know where where they are as an individual yeah i think it's a great question it's one that commonly comes comes up when i give talks actually is should should women do their exercise differently to men especially with this theme of whether they should exercise before or after eating and um there's a bit of confusion as well because i think in some tv programs that have been shown over here at least um it was suggested that that women respond very differently to men and it's true that women tend to burn more fat than men during exercise so when we control for for all of the important factors and we compare men and women women tend to be able to burn about 13 more fat than men but that's actually relatively small that difference compared to other factors so if for example we look just within the group of men or within the group of women then the difference between the highest and the lowest person is more than 300 percent difference so there are greater differences between individuals within each sex than there are between the sexes so i think it's our next step so we've done work on this and we're keen to do more work on it the next step is to understand what are the factors that determine why one individual can burn a lot of fat versus another and it's sex is probably one of those factors but it's probably not not a big one so i guess in rather than a fat occident oxidation gender gap it's more of a gender overlap in that regard if we if we extend that to say the menopause then it does link because one of the main reasons we think women can can burn more fat than men is the hormonal status of women so estrogen and amazingly they have done the studies where they've given men estrogen and immediately their fat oxidation increases um and it probably also depends on the number of receptors women have to to estrogen so the estrogen is a hormone that that will stimulate a variety of responses but it can only stimulate those responses when it binds to its receptor and we've actually found that women with more of the receptors for estrogen show the higher rate of fat oxidation so there's this complex interplay between the hormone but also the physiology other aspects of physiology of the person um to actually get a response there so that's sort of the science showing you all these differences um if you're listening to this trying to figure out what to do and maybe let's let's take that example as a as uh as a woman is i think a great example which is um something that we end up talking a lot about right which is that your body is changing and what worked for you when you were you know 35 is maybe different and this is true for men as well but it's particularly true we see with with women because of this really big change around menopause like what should they be doing how important is exercise around menopause when one of the side effects we often see is weight loss but i think there's also other implications you talked about um touched on i think earlier to do with sort of bone density um and how do we think about both exercise and diet i guess um together through this this period yeah definitely those are the the points i would uh most focus on in in people who are considering how to to mitigate the effects of menopause and um with with the kind of strength loss and and potential loss of bone mineral density it's where strength training really becomes comes into play so um ideally lifting relatively heavy weights um or it can be running as well so you get a reasonable impact when you run much more than cycling um the forces that go through the ground when you hit hit that ground and through your leg and foot also stimulate bone growth and tendon strengthening so combining either weight training and or running with diets can really be the key there so on the dietary front there's probably four main areas i'd i'd consider one is calcium so are you getting enough calcium in your diet and the second is vitamin d um which i know in america in the us that quite a lot of foods are fortified in the uk not so much so you might need to take a supplement there especially if you don't live in a sunny climate and the third would be omega-3s so making sure you eat plenty of oily fish to get your omega-3 and the fourth would be adequate protein intake because we often actually forget that a lot of bone is actually comprised of protein as well and when we eat protein one of the the hormones that is released is known as glp1 that also stimulates bone growth as well so those four dietary factors combined with some form of exercise that is going to load the bone is probably crucial there happy i think that's really fantastic and very actionable um advice um i would like to maybe just sort of summarize what's been a very wide-ranging conversation and where i think there's many things that we haven't really had a chance to uh to get into so i look forward to hopefully coming back to this um in in the future i guess the starting point is this really rather surprising um fact that exercise is not the key to weight loss it's very important for your health but actually on its own is not really going to transform um uh your your your weight loss that actually exercise starts at a lower level than i think um many of us imagine so apparently i can do a brisk walk and i think you said 30 minutes a day was really going to have an impact on on my health and i didn't even have to do this all in one go so i could actually have um uh you know maybe like three uh uh pieces which i think again is uh not at all what uh i think many of us understood you then explained there's actually two sorts of exercise and that this strength exercise which is very different from this little longer term cardio are both important that the longer term exercise which i guess is your your brisk walk through to running or or cycling is great for our cardiovascular system and our blood pressure and trying to to deal with heart disease but actually strength exercises is very important and if we want to stay strong long term and that can even mean so that we can continue to get in and out of a chair and things like this then actually we need to to do that because you painted this slightly depressing story that i think from about 35 we're all getting weaker and weaker and therefore we sort of have to fight against it because you know most of us are doing what i'm doing right now which is sitting on a chair talking and the good news is that apparently that burns some calories because i'm using some muscles but it's not really enough to get me out of that out of that chair in the future is that right have you that's correct yeah good um and then i think we talked about this amazing studies that you have been doing and that you are recruiting for for the next stage of looking at the impact of fasting on on health and i think this very counter-intuitive discovery that actually you know doing exercise while well fasted can actually improve some of your health outcomes um and that for most of us the answer isn't to only do this fasted exercise but actually a combination and i think in general one of your your stories here is actually a sort of variation is uh is important and this flexibility of your of your body um is is very important he taught us a bit about glycogen and why people hit the wall um when they do their uh marathon and there's a lot of stuff that professional cyclists do for fun that we probably don't want to to do at home that as a result they have these amazing gut bacteria these different microbiome and we think there's something really interesting but this is really an area that is is still very early and then we talked to about about the food that you need to eat if you're exercising um we understood that actually our muscles are mainly made of protein which i guess explains why people talk about protein all the time that we do need it it's not just a marketing myth created by by big food companies but that actually there have been clinical studies where they've shown that if you drink a pint of milk that works just as well as a fancy powder and that although there is some scientific truth around this idea that you know in the hour after exercise you're going to incorporate even more protein actually if you're not a professional athlete if you're eating three meals of a day and that those are sort of balanced meals you know with probably whole foods and proteins you're fine if you are doing something like time restricted eating and you end up with a very long period between exercise and food then actually potentially you should you should think again about that and either maybe adjust a bit or even think about supplementing for example with with calcium and then i think we finish with this fascinating stuff about personalization where you said it's true that women on average burn i think you said 13 percent more fat um the men which sounds like a really big difference uh it's related um to estrogen but when you go and look within the differences within uh women for example you're seeing this 300 variation which is very similar to some of the things that we've seen in in some of the big zoe predict studies looking at uh you know inflammation and things so this huge variation within individuals and so you know it's a one-size-fits-all uh guide is going to have the same problems as everywhere else but this does mean that as you go through menopause there's a big change because of um the uh change in hormones and that there's really some very specific things i think that you recommended and let me see if i if if i've got that right so firstly you're going to be losing strength you're going to be losing bone mineral density so you really need to think about that in addition to thinking about um how your diet might need to shift um because of the the weight gain that may go with this and so i think you're pushing you know particularly here quite strongly that you need to think about strength conditioning can you be lifting quite heavy weights because i think you're explaining they need to be quite heavy to have that uh impact um that interestingly actually running is a form of strength conditioning which i think will be a surprise surprise to me i suspect surprise for many people and that on diet you had some very specific um recommendations so calcium are you getting enough vitamin d uh omega-3 and for people um who are not vegan then actually uh then um sort of dairy-based products um uh were a good solution there and uh and if you're not vegetarian then sort of oily fish in terms of omega-3 and then in addition making sure you're having adequate protein intake where again you said you know it's you don't need to be doing some sort of special shake it's about understanding that you're eating a sort of balanced meal that's got got lots of protein yeah javi that's an amazing sort of tour across um all of these things i think that's really fantastic sort of actionable takeaways javier thank you so much i think that was uh so interesting we enjoyed it very much and look forward to having you back in the future with the results of those those new studies my pleasure thanks for having me thank you to javier for joining me on zoe science and nutrition today we hope you enjoyed today's episode if you did please be sure to leave us a review and subscribe if you're interested in learning more about zoe and the best foods for your body you can head to joinzoe.com podcast and get 10 off your personalized nutrition program finally if this episode left you with questions please send them in on instagram or facebook to zoe and we will try to answer them in a future episode as always i'm your host jonathan wolfe zoe science and nutrition is produced by fascinate productions with support from sharon feder here at zoe see you next time [Music] you

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Length: 58min 52sec (3532 seconds)

Published: Mon Apr 11 2022