In this episode, Dr. Rena Malik, MD sits down with Dr. Gil Carvalho to explore the benefits and myths surrounding fasting and ...

fasting-facts-vs-fiction-what-really-matters-amp-best-times-to-eat

Fasting Facts vs Fiction: What Really Matters &amp; Best Times to Eat

what is the evidence in terms of fasting are there true benefits or is it more the calorie restriction from time restricted eating the balance without us is telling us that it's mostly the calories now that does not mean that the benefits aren't real they're very real and they're very uh they can be very impressive some people have you know revolutionary results by fasting because of the weight loss and and all these Downstream benefits and sometimes by by fasting people also remove some of the worst foods that they were eating so a lot of the snacks and all of these a lot of these foods that they would bench sometimes late at night or something like that those are the ones that are removed instead of the main meals and so uh that also contributes so I don't think there's a contradiction I think the benefits are absolutely real I think fasting is a very valid approach that works really well for some people works incredibly well for some people now I wouldn't tell everyone that they have to go fast otherwise they're hurting themselves I think that that logical leap is where I think influencers go too far the results that we have don't point to any benefit of fasting that is independent from calories there's there are questions around the time of eating the the chronobiology that's a related but separate question but fasting itself just a block of time without eating we don't have anything compelling that indicates that there's anything kind of magical or anything specific about fasting that's delivering that you can't get elsewhere even this idea of autophagy which is very popular in the fasting Community you can get autoph you can activate autophagy by cutting cies as well so caloric restriction or fasting if equated for calories you get autophagy in both so and the fact that we basically in these trials when they match for calories people fasting and people not fasting they see similar changes uh so this is telling us that it is probably through VI via the calories but I wouldn't that to me doesn't minimize the results that people get by hook or by crook the results are real and great so for the people who do well in fasting who like to integrate fasting I I often say it's out of the fads or out of the trends it's my favorite one because it doesn't involve doing anything super dangerous or eating something crazy or you know it's just we're telling westerners to eat a little bit less and uh if you tell them to count calories or to eat less and move more you're pillared but if you tell them to intermittently fast and do high-intensity interval training you're a genius so hey whatever gets the result yeah um you said there's a chronobiology so is there value to circadian fasting or follow your following your circadian rhythm so there there is a bit of um heterogenity in the data there are some trials that suggest that eating the same meals earlier in the day is a bit better metabolically so really interesting studies um looking at the same exact foods but just shifted earlier versus shifted later and they've even matched the fasting so everybody's fasting the same the same amount of time so everybody's eating let's say in an 8 Hour window for example or 10- hour window but that window gets shipped it earlier in the day versus later in the day and there are a few trials that show that there there seem to be some benefits maybe in terms of weight loss in terms of insulin resistance glucose metabolism style type metrics to eating earlier in the day and there is some circadian data supporting this we tend to be a bit more insulin resistant late at night uh so there might be something going on there I should also say that there are trials that don't recapitulate this but there are possible reasons sometimes the window is not as short as it could be so people argue okay maybe they just did it didn't just crunch the window long enough so there are possible methodological reasons why it's not seen I'm open to the possibility that eating Foods earlier in the day is a bit better I think what should be said is that and this I think is is agreed upon uh pretty much universally is that if there is an effect of this circadian uh circadian acity of eating earlier in the day it is a much smaller effect than calories overall so yeah if you're going to if you want to do this I see no problem but bear in mind that the that still the the the overall goric balance is going to be the main lever for weight maintenance and glucose metabolism and food quality that's another caveat I think sometimes people get hung up on on the fasting and these these new trends and they forget the old things that we know and oh as long as I'm fasting then I'm going to eat this feast after sometimes people say the problem is not the fasting it's the feasting so it's people people fast for a number of hours right and then they feel like okay I work really hard now I can reward myself and they go and eat a really unhealthy meal not everybody does this but it's it's a a caveat um if you're eating unhealthy Foods probably you're undoing all the the any benefit that you got from the fasing yeah I think that's absolutely true but I do think that some people do experience better sleep when they eat earlier because their body can you know not be busy digesting their food and so I think that may play a role in some of that chronicity as well um and then we know that overall sleep will boost testosterone increase increase testosterone allows you to get more muscle mass and so maybe there is something there but again I think you're you make a good point that if you're eating bad during your fasting window even if it's feasting window even if it's earlier in the day it really doesn't matter yeah yeah you're you're kind of uh undoing the the good I have no problem with that if just if if people feel better for whatever reason eating earlier in the day as a night owl uh I don't I don't exper I can't say that I experien that uh but I completely believe and I don't see a problem if people want to sh shift their their meals earlier in the day if anything it has um evidence to support it you know I think in in medical school right in our training at least in the west we learn very little about nutrition and I've I've got on record I've said this I wish we knew more about nutrition because that's prevention right nutrition is one of the pillars of Health that we should be spending our time counseling patients on and helping them guide this this issue and because we're so very I mean I say all the time the Mediterranean diet is the most studied because that's accurate right so most stud has has an abundance of of data but when someone comes to me and says hey I'm doing the carnivore diet it's great or I'm doing a a raw foods vegan diet it's great you know I could only tell them what I know which is minimal right like I I can't know everything about every single diet but why do you think that we haven't adapted our training in medicine to really emphasize nutrition more I think it's it's it's a failure of the medical system but also so Society why do we have this problem I think we should be learning about nutrition about the fundamentals from Elementary School it's so crucial the fact that the fact that even Professionals of Health don't learn about it and I completely agree with you and I went to medical school I learned precious little there was maybe one class uh in my third year uh where we learned a little bit learned about what nutrients are essential nutrients vitamins but it's so rudimentary to me it's it's it's crazy that a we're not teaching everyone about this thing that everyone does and is so fundamental for health and so many of the main causes of death of our society are critically uh influenced by what we eat massive failure I think of Education in general and then specifically for for people who specialize in in medicine and in in health to not have that training is crazy uh now what sometimes will happen and you may I don't know if you have this experience is doctors will work with registered dietitians so they refer um patients to an RD for more specialized uh uh nutrition advice so I think that can work it's kind of a compartmentalization of of the advice or of the competences but yeah so I don't think it's realistic for every doctor to be a specialist in depth of nutrition but I think having a a strong Foundation would be critical and even starting much earlier I was reading this article about the education in Japan and it's a key part of Japanese education starting in elementary school so the kids eat together they they present boots to classmates and they talk about nutrition at the age of like six or seven so it starts young and so here we have almost the opposite where the foods that are served in schools are of the worst kind and the foods that are served sometimes in hospitals are of the worst kind so we really don't have an Institutional support for for something that a suit should be so essential and then of course we pay the tab later on in terms of diseases and and early death um yeah I don't know I guess everybody agrees with this but how do we change the system is is the the the tricky part I I think part of it is is giving medical students this this this information I have a number of viewers who are medical students or you know the researchers of other fields but yeah I think until we have and we given some lectures actually to medical schools and nursing schools kind of touching on some of these topics so I'm always really excited when I get an invitation to do something like that which happens occasionally but not as much as it as it should and it shouldn't be it shouldn't be let's get this YouTuber to give a one hour thing it should be here's this curriculum of nutrition over the four years of medical school right um but yeah I don't know exactly how we how we change the system but I think is if we don't we're in dire strings yeah and I think part of it is you know if you go to your doctor and ask them about nutrition you may get a poultry response because depending on the doctor and their you know historical experience nutrition space and how much self-learning they do as you mentioned even you learned so much from studying seed oils for example but like I learn every day when I'm creating content and reading and reading research and you know trying to find things out for my patients and I think that like there's some doctors who don't do that don't have time for that have very busy practices or seeing 50 patients a day whatever it is and so they know what they know and they don't have time to delve into these topics in detail and so they may not have a great answer for you that doesn't mean that I think in general they're not you know they're going to tell you the basics right which is maybe move more eat less or calories in calories out or and that may be frustrating when you're seeing all these things on social media saying it's not just that but is it is it just that do you think it's just calories in calories out is that a reasonable response I think it's a very incomplete response and it's not particularly actionable for most people that's why we have this clash it's not that it's incorrect it's that it doesn't tell people what to do it's like telling people oh you're poor make more money it's not it's not actionable it doesn't help me um calories in calories out is basically it's explaining the mechanism but how do people get there you have to give people tools to implement in real life that's where that's where this type of advice is not good and that's where things like oh fast stop eating at 4 P.M and cut all the carbs from your diet cut all the fat from your diet these things uh sometimes are overhyped some of them are not particularly based on strong evidence in terms of saying that all carbohydrate is bad or all fat is that but what they are is very actionable and very effective at least for some people and very simple you tell you explain that in 5 seconds here's what you do everything with carbohydrate now is poison eliminate that from your diet you eliminate most foods that you're eating on a typical Western diet it's an erratic Elimination Diet you lose weight same with low fat same with all these different things the the twinkie diet all these things where you're only supposed to eat one thing sooner or later you're fed up with that thing you're you're you're uh you know you're nauseated and you stop eating you're not eating 3,000 calories and you you lose weight we need to do and this is a challenge that I I think it's it's it's behooves us who you know we we're taking on this challenge you and me and so many others where we're trying to bridge scientific knowledge with the public and it's it's not easy um but it's it's I think our task to come up with something that is evidence-based and empowering and uh actionable that gives people the results shortterm but also supports their their longterm term Health that we don't short change them uh for kind of a popular crash diet not easy I'm not pretending to have the magic recipe but that's essentially what I try to do with my content and and you know it's changing over the years as I get feedback as I learn more from viewers also and it's it's kind of this this dance right um I'm I'd love to hear also your your experience uh with you have a much larger platform than I do so maybe you have other insights that I haven't even gotten to yeah you know I think you have to meet people where they are and and people are all over the place in terms of um what they're ready to change about their life and you're right I think sometimes getting on a diet that you enjoy right like say you really like me and you're like oh the carnivore diet is great it gives me all the things I like and I get to lose weight and you know and and like you could be like okay how can we make this healthier right how can we make this version of your diet healthier um how can what are the things that you eat and you know taking it like sort of in an atomic habits sort of way take one small change at a time and incrementally do that till you get to a diet that is sustainable longlasting and that you can actually you know maintain for years on end I think that's sort of the challenge with some of these diets is yeah you can do them for two years maybe uh three years even but at some point you're like you know what I just want to eat a piece of pizza or I just want to eat a piece of bread and like I can't do it anymore right so I think it's sort of meeting people where they are and making these incremental changes that are very individualized because as you mentioned people are very individualized and they may have sensitivities and they may have issues and they may have poor sleep and they may have other things that you have to take into consideration and that's where you know the stuff we do is great we give general information to people but it's not applicable to every single individual I mean the the the overall sort of pillars of information are applicable but there's individual Nuance that we can't get on when we're talking on social media completely agree with that that's something that especially with nutrition where there's so much variation I'll make a video going over a topic and invariable youall get people saying well but I experienced something different and someone else will be on the other end of the spectrum so that's been a learning experience for me trying to make content that communicates the pillars of the evidence but at the same time kind of trying to help people trying to individualize a little bit although it's so limited because if you're talking to however many thousands of people you can't into personalize any meaningful level so you're always kind of generalizing a bit um but what we said about uh sustainability long term is so crucial and this is a a common pattern that we see with these trials with all of these diets by the way the low fat the low carb the vegan all of these interventions after a certain period from six months to a year around there people just start falling off the wagon like crazy with all these diets even when they get really impressive results initially even with the results it's not enough for most people to stick to the diets this is something that has really stuck with me from from looking at these trials whether it's uh you know and even things that aren't randomized where it's targeted to help people with a specific dietary pattern and all the investigators are motivated and believe in that diet and you still see long term over two years three years terrible sustainability as a whole and then there's always the 5% or 10% or whatever percentage of people that do stick with the diet and love it and those I think become the evangelizers on social media uh that are very angry that they're not being listened to because hey it works so well for me how it how come isn't everybody isn't doing the same thing and again there's a nugget of Truth there that it did work for them and they were able to stick with it but unfortunately this change of habit with food specifically it's so difficult for most people to to sustain stain so there I think is is another challenge is get how to get people to stick to these these changes that's where another somewhat You could argue it's an advantage of a Mediterranean style pattern traditional Mediterranean because it's a bit closer to what people are used to it's a mix of foods and it's not super lowfat or super low carb you're not completely eliminating any food group so perhaps a little easier for the average person to to attain to that uh in the long run than these more extreme varieties if you enjoyed this clip of the Reena malic MD podcast make sure check out the full episode with Dr Gil carvalo right here

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