Training fasted definitely burns more fat, right??

It’s a myth that needs its own podcast. 
We are busting one final gym myth - is fasted training better for fat loss? You might be surprised!

Time Stamps
00:00 Introduction and Overview
04:29 The Role of Glycogen in Fasting
08:10 Fat Oxidation vs. Fat Loss
13:28 The Impact of Fasted Training on Body Composition
27:15 Determining the Need for Pre-Workout Meals Based on Exercise Intensity
31:36 Conclusion and Next Steps


Jono (00:03)
Welcome back to the BiteMe Nutrition Podcast. Today I have Jenna back with me, which is very exciting because we are going to talk about a topic which we touched on in a previous episode and we dabbled with in social media a lot. But today we're going to do it justice. We're going to unpack it properly and we're going to go through it in all its depth and detail. So what are we talking about today, Jenna?

Jenna (00:27)
We're talking faster training. I feel like this is, it was a nice coincidence that we didn't have time to finish this one off in like the gym myths because this is a whole topic all in itself. But more specifically talking about this idea of faster training or faster cardio in particular being superior for fat loss or body composition.

Jono (00:51)
Yeah, I think that was the myth we were going to cover, but you're right. I'm glad we're going to go a bit further than that because there's probably more implications for training in general and getting people to understand all of those differences and the differences in fueling and what our body is doing in a faster than fed state. And, you know, I guess it's always probably good to give people a better answer than because we say so, which is probably what the last podcast could have been. But at least now you'll understand.

Jenna (00:52)
So yeah.

Jono (01:20)
why we say so. And we can dive into a bit more of that. So I guess, like, as always, it's good to start with some definitions. What is fasting?

Jenna (01:33)
Yeah, so I guess traditionally when we think of a fast, it is a 12 hour period where we have abstained from mostly food, but then some kind of drinks as well. So anything that has a caloric value or can potentially increase our insulin and all of that kind of stuff. So usually it's a 12 hour sort of window that we're thinking about for a fast, but obviously with all of the intermittent fasting trends, that has changed a little bit, but I guess for our purpose sake, that's kind of what we're going to define as a fast. So the best example that I think most people can think of is your overnight fast. So you've had dinner, you know, six, seven o 'clock. If you're a Nana like me, that's in bed by eight. And then you're going through an overnight fast where you're not eating anything and then waking up, having breakfast at some point. So that's probably our most common fast that majority of people are going to go through.

Jono (02:33)
Yeah, unless you're getting up for a midnight snack. And if that's you, then we can talk another time, I suppose. So what happens during, whether it just be our sleeping fast or whether it's a fast that we're intentionally prolonging, maybe someone, like you said, is doing that time restricted feeding, intermittent fasting, 16, eight, what's happening in those fasts of over like 10 hours?

Jenna (02:42)
Yeah. So even though like even when we're having a big period of time without food, our body still requires energy. And so if we're not going to give our body energy, you know, in the immediate form, which is food, it's going to start relying on its energy supplies, sorry, energy stores, in particular glycogen. So glycogen is our storage form of glucose, which is especially our brains most preferred substrate, I guess, in terms of producing energy. So when we're not giving our body enough food to have enough free glucose to produce energy, it's going to start breaking down our glycogen stores. So it is really important that we remember that even though maybe we're not exercising, we're not doing all that kind of stuff, especially during a sleep as well, things like your brain and your heart and your lungs and a lot of your organs are still using energy in order to keep you alive. So as our blood sugars start to drop, especially if we use the overnight fast as the example, the glycogen in your liver and your skeletal muscle, they're going to start to get broken down. And so what I always like to think of it as, especially like I said with this overnight fast is going to bed with a full battery. We've had dinner, we've, you know, stocked up all of our glycogen stores. We're ready to go into our sleep. As we're sleeping, the battery is slowly getting dwindled away and then we're waking up, you know, the next morning with not a full battery anymore because our glycogen has been broken down. And so typically we would eat to refuel those stores back up. And this is kind of where it leads us into should we or shouldn't we eat before we train?

Jono (04:52)
I don't know training with 30 % battery sounds awesome. Wouldn't that be wouldn't that be really good for? I guess if we if we will definitely come back to performance. But if we're coming back to kind of the base or the the driving force behind the myth in terms of fat loss, right? Like I know a lot of people preferentially train fasted or support training faster for fat loss. Is that

Jenna (04:55)
Oh, sounds like a great training session to me.

Jono (05:20)
If my training, if my fasting window just impacts my glucose or my glycogen, rather than my glycogen, does it have any impact on fat? Like what's going on with how my body's using fat or losing fat in that window or during my training?


Jenna (05:38)

Yeah. So when our body no longer has enough glycogen or if we have a high fat meal per se, our body will use fatty acids as a way to produce energy. So we do have, you know, we're not just relying on glucose stores. We do have fatty acid oxidation as another sort of backup mechanism. And I guess this is kind of where this fat burning and fat loss kind of gets. The lines get really, really blurred and especially on the old internet because if you're burning fat, then you're going to get lean. But I guess if we bring that back to the burning fat is what we would refer to as fat oxidation. So this breaking down of our fatty acids. And so that could be stored fatty acids. It could be fatty acids from our meal. And so we're going to break those down to produce energy. It normally occurs, like I said, when we don't have glucose ready and free to use as energy and also can happen after we've had a really high fat meal. So if you've gone and eaten a ton of eggs and cheese and all of the really fatty food, I don't want to demonize those foods, but anyway, you've had a really high fat meal, you're going to use a proportion of that as energy. It's just, it is what it is. But it is important to know that that fat oxidation or that fat burning, the breakdown of fatty acids is not inherently fat loss. You can still be burning fat and not losing weight or body fat. Because if your caloric intake is still matched, you're not in that calorie deficit that is required for fat loss. Does that make sense? Because I feel like that it's such a nuanced thing that can get misconstrued so much.

Jono (07:40)
It can and it's it is probably the crux of it. People understand the difference between fat loss, i .e. being in a negative energy balance, eating less energy than you're burning, versus fat oxidation, i .e. using fat as a source of fuel, either from maybe some adipose tissue, but also from your diet. If you can understand that fat loss and fat oxidation, oxidation is just a fancy way for burning. Two different things, then I think we might be okay. So hopefully, dear listener, you now know that fat burning and fat loss are not the same thing. So even if you hear people say that fasted cardio increases your fat burning, they're right. But it doesn't necessarily increase your body fat loss, which is, let's be honest, probably why most people are doing fasted cardio, right? It's a fat loss. They don't really care what... fuel they're burning.

Jenna (08:44)
Exactly. And I guess, you know, if you don't believe us, that's why everything we do is evidence based. We always take things back to the evidence. And so look, we've got a ton of studies and two that I want to mention just that helps to kind of back this up. And as always, like in the show notes and everything like that, if you want to go back and have a look. But there was one study back in 2014 by Brad Schoenfeld and Alan Aragon.

Jono (08:51)
Ha ha.


Jenna (09:14)
I hope I'm saying both of them right. But anyway, they that's where my brain went to as well. And I was like, Oh, I've got to really pay attention to what I'm saying here. But anyway, they they looked at the effect of fasted and fed exercise on body composition. So exactly like what we're aiming to do with bastard cardio with is it is affecting our body composition.

Jono (09:15)
Yeah, that's it. I always want to call him Alan Aragorn because a lot of the rigs, but it's not, it's definitely Aragorn.
Mm, mm.

Jenna (09:44)
And essentially they found no difference in your body mass, your BMI, your fat percentage, your waist circumference, your fat free mass. So a lot of things that we would use to measure body composition. So absolutely zero, zero difference. And it is always important to note that between their two groups, the calories were, they were in a calorie deficit, both groups. And they had their total energy and then macronutrients matched. So they were both in a deficit, which would result in weight loss, but there was no difference in the amount of weight loss that they, or body recomposition that they'd seen between those two groups. So automatically we can kind of assume that, yeah, all right, well, faster training is no better for body recomposition than fed, so long as we're in a calorie deficit. And then another interesting, it's a little bit more complex but to try and break it down as simply as I can. It was by James Frampton in twenty twenty -two. So quite a recent one. Um and so this time they looked at less body composition but more kind of like behavioral things. So what the effect of of fasted exercise and fed exercise had on your energy intake, your expenditure, your hunger, and your, I guess your hunger hormones across the day. And what they found is they separated, this is where it gets really complex, but they separated it into essentially four groups of people that were fed before exercise and had a standardized post -training meal. They had people that were fed that didn't have the standardized post -training meal, those that were fasted, no pre -training meal, sorry, post -training meal, and then fasted with the post -training meal.
Oh, too many pre's and post. Anyway, essentially what they found was that those that were fed and had the post training meal, that they ad lib, so I guess on your own accord per se, they had lower energy intake across the day. So they kind of didn't overeat.

Jono (11:41)
No, you got that out. That was good.

Jenna (12:08)
Towards the end of the day or across the day. And then interestingly enough, those that were fasted and didn't have the post -training meal, same thing that they didn't necessarily over -consume calories across the day, which we would, I guess, maybe predict to happen. But what did happen was that they had lower energy expenditure.
So yeah, they were eating less calories, but they were also moving less, which, you know, also comes with another sort of its own risk. And they were damn hungry all day. And so if you are someone that is trying to change your body composition, having faster training and look, we're not talking post -training meals today, but if we're having that faster training, we're going to be doing less movement and we're going to be hungry. And if you are someone that, you know,

Jono (12:36)

Jenna (13:05)
Wants to listen to your hunger cues, number one, but maybe doesn't have a great relationship with food. You're probably going to be more inclined to overeat. It is very individual, but essentially bring it all back to there is no major benefits in terms of body composition being fasted in training. Long story short.

Jono (13:28)
Yeah, yeah, I love those those two studies, the Aragon and Schoenfeld one in particular with a lot of energy and macro nutrient intake is matched. And really all their testing is I guess how it's distributed across the day, like, have they used some of their energy and macronutrients pre or have they kept everything for after training and as we'll get into performance in a second, you can see that there's probably differences in performance based on when you distribute it, but there's no differences in body composition based on when you distribute it. So hopefully you can all see where we're going with that. And that second study scares me because the thought of, look, obviously we're pretty pro eating before we're trained. I don't think we're being subtle about that. But the thought of someone not eating before or after, what the hell? Like if you have to skip one, sure, skip your pre -training, but don't skip post -training. Like, oh man.
I would be a shell of a human being.

Jenna (14:29)
Oh, you could, I could only imagine the kinds of foods that I would want to eat. Like it would just be a free for all if I like.

Jono (14:37)
I'd also be super interested if they took that study, like if they did that for, I actually don't know, did they do it for just 24 hours or did they do it for a few weeks? Because if it was just 24 hours, sure, the people that were hungry may not have eaten more that day, but I reckon if you stack a few of those days together, by day two, by day three, by day four. Be very curious to see.

Jenna (14:59)
From memory, I do believe it was a 24 hour study, but I'd have to go back and check. But yeah, exactly. Like, yeah, OK, once off every now and then maybe, yeah, it doesn't have a huge impact. But like you said, but yeah, like day after day, month after month, and it's got to start having a role in what we're doing with food. Absolutely.

Jono (15:10)
you get away with it.
I know I've had lots of chats with clients. I'm sure you had this very similar chats as well of like this idea of, oh yeah, I was just really hungry on that day. And we sort of ask a few more questions and they're like, yeah, but I didn't do any training that day. I don't know why I was so hungry. I was like, okay, what did you do the day before? Big training volume. Oh, what did you eat? Oh, I didn't, you know, and they've missed the pre -training meal or post -training meal they've underwritten. So sometimes the consequences of that don't show up until the following day.

Jenna (15:49)
Mm -hmm, things don't reset at midnight.

Jono (15:51)
No, if only. And just to, we're not saying that if you're hungry, you shouldn't eat, right? Obviously you want to feel adequately. We want you eating properly and doing all of these sorts of things. But if you're setting up your nutrition in such a way that's making you hungrier than you need to be, I think that's what we're trying to fix. That's not fun for anybody, right? So, okay.

Jenna (16:14)

Jono (16:15)
So hopefully by now people are starting to believe us when we say there's no impact on fasted training and body composition, right? Whether you eat before or after, it's probably much, well not probably, it seems to be much more important to make sure you're getting your daily targets and you're getting your daily food and you're doing all those sorts of things. So, okay, let's say that I don't care about body composition. Why would I eat before I train? Okay.

Jenna (16:25)
Mm -hmm.

Jono (16:45)
If they get me the same body composition outcomes anyway, then what if I prefer training faster? Can't I just do that?

Jenna (16:53)
The answer is yes. You can't...

Jono (16:54)
Sorry, yeah, that was a bad question. What is optimal? Does it have an impact? That's what I should have asked.

Jenna (17:01)
Yes, absolutely. You can train fasted if you want to, but hopefully at the end of this, you realize that it's maybe not something that you should ever want to do. Yeah. So I guess when we think about what is exercise, we are using our muscles where our muscles are going to start wanting more energy. And so where if we're not eating before we train, we're going to be breaking down like.

Jono (17:09)
You will not want to.

Jenna (17:29)
We said, maybe our fatty acids or our glycogen stores to allow our muscles to have said energy to do the work. The kind of substrate that your body uses, and this is, I guess, our argument that we'll have a little bit of chat about later anyway about, you know, when is the right time to eat before we train, like what kind of exercise does require eating and not. But the kind of substrate that your body prefers or breaks down predominantly and the key word being predominantly, it's not an all or nothing. But if the type of energy we break down depends on the exercise and the exercise type that we do. So we do know that if we do more low intensity kind of exercises, we are predominantly breaking down more fatty acids. As intensity increases, your body starts to rely more and more on the breakdown of glucose to produce that energy. So, as we start shifting into higher intensity exercise, there's less fatty acid breakdown and there is a hell of a lot more glucose being used. So that is kind of our number one reason why, well, I won't speak for you, but my number one reason why I always recommend clients to eat before they train, especially if they are doing like that high intensity exercise. If you're not eating before you train and doing higher intensity exercise, you're going to hit a point where your body can no longer provide your body enough energy to support the kind of exercise that you're doing. When that happens, you're going to fatigue. You're going to, if you're an endurance runner, the common thing is you're going to boink, you're going to hit the wall. Your body is not going to let you go any further. And so if you're training because you want to enjoy training and to you have performance goals, like you're wanting to get stronger, you're wanting to get faster, you're wanting to do more work, then eating before you train is going to allow you to do all of those things. So I guess it comes back to the quality of your training session is why you want to eat before you train versus more, you know, the weight loss side. No one should be exercising to lose weight. I think that that's a very important thing to always put out there. If you are just exercising to lose weight, very kindly, you need to go re -evaluate your life choices and maybe have a think about, you know, what your relationship is with food and exercise because exercise is far more than just weight loss. So taking that out of it, if we want to focus on the quality and to get the quality we need to eat.

Jono (20:23)
So if you're interested in a higher quality training session, you should eat before you train. Is that basically? And so if you're not interested, then that's fine. But why are you not interested in a higher quality session? I don't get it.

Jenna (20:42)
If you enjoy feeling like trash while you train, go ahead. Continue training fast. It's, it's, it's, yeah, it's a really great way to, to encourage you to keep exercising. If you just feel like absolute rubbish every time you do it. Um, but yeah, if, if you want to get any kind of performance anytime kind of quality, which one would argue, that's the main reason why you should be exercising that. Yeah.

Jono (20:47)
Oh, my favorite. Hmm.

Jenna (21:12)
Eat something.

Jono (21:12)
Yeah, yeah. And two quick things I want to address in case people are thinking this while they're listening. What if you're like, yeah, but I still want to lose fat and train well. You can totally aim for both of those things. But remembering that training isn't going to be the main thing. Driving fat loss at all, that's going to be the rest of your day. So training is going to be driving muscle gain, heart health, bone density, tendons, ligaments, all these other wonderful things. So let's almost separate the two and be like, let's maximally fuel training and you can deal with the fat loss with your overall dietary sort of intake. And then the other group of people that might be sitting there, cause you said like, if you want to feel like trash when you're training than training faster. Whereas I know that there's people when they first get introduced to this idea go actually Jenna when I eat before I train, I feel worse. So we are going to know what order let's do that now. Let's just add to that now. So for those people who have said like, I can't eat before I train, I feel crap beforehand. Can you run through a few of the common things mistakes that people are making and I will quickly preface this by saying, Jenna's probably too polite to say this, but you absolutely need to go follow her for more information on this stuff because she's posted many, many posts talking about this topic from many, many different angles, right? It's talking about bigger meals, smaller meals, time of day, weather you go. So we won't go in depth into this question, but that's because Jen has already done that too many times and I don't want to send her mad. So in a short kind of, what are some key takeaways of eating, how to eat before I train without feeling sick or feeling comfortable?


Jenna (22:54)
Yeah. So normally if someone says to me, yeah, I've eaten before I've trained and it doesn't feel good for me. You know, maybe I feel like I'm going to be sick and all that kind of stuff. The first two questions that we have to ask ourselves is, well, one, what were you eating? And two, how close were you eating to training? So what you eat is going to have a big impact on your performance. So, you know, we've talked about, well, this is the bit that we've... probably not going to go into carbohydrates. You need to eat some carbohydrates before you train. You want to know what kind and how much like I said, Instagram. But if we're having say, you know, we're getting up before we go to the gym in the morning, we're having some eggs with our toast and you know, all that kind of stuff. The protein and the fat that is in that meal, they digest slower, which is, you know, why we want to spread them out across the day, they help you to feel full to feel more satisfied. You don't want to feel full before you exercise. Like that is just asking for a bad time. So normally, well, not majority of the time when people have eaten something before they've trained, they've included one of those two things, which has contributed to contributed to them not feeling the best during training because it's, it's, you know, food sitting in your stomach. So that would be my first argument of like, well, what are you actually eating? And the second thing is how much you, oh sorry, how close to training are you eating? So if you're eating, you know, the example of the person that gets up at 5am to, you know, hit a training session, those crazy people that get up at 4am, you know, if you're having that big normal breakfast half an hour before you train because you want to eat before you train, then yeah, that's definitely going to impact it because we've eaten now too close to our training, let alone what the kind of things are that we're eating. So, if you are someone that has tried eating before you trained and didn't feel great, my two suggestions would be one, take a look at what you're eating, making sure it's a simple carbohydrate. Two, let's try and, you know, at least an hour before, sorry, at most an hour before we train, try then and then as you tolerate more and more, so start with something small, you can practice this and you can build it up over time. And so you will get to tolerate more food, more carbohydrate, closer to training with time. But you do have to practice it, but you have to start further away in something smaller. Yeah.


Jono (25:30)
Yeah, that's enough. Yeah. I can see you wanting to keep going because you do want to give people all the information. But look, I think what will be kind will link specific posts in the show notes. So yeah, you can also check out a few of those which will take you directly to this post. But yeah, I think if you're remembering what and when, and also the fact that yeah, you've got


Jenna (25:36)


Jono (25:55)
literally adapts to be able to handle more carbohydrate in the same way that your muscles adapt to being able to handle more load as you train. So if you're like, I'll never be able to squat 80 kilos, I can't squat it now. Of course you can. You just need to build up to it. Yeah, yeah, yeah, yeah. Instead of like, oh, maybe I should start with the bar or start with the, I don't know, don't ask me training questions. But you know, it is an adaptation over time. So don't try it once and throw in the towel. There's definitely...


Jenna (26:08)
so I should never try to squat. Yeah.


Jono (26:26)
Some of those posts in there. And then sometimes what I found is I think because we are very, I wouldn't say overzealous, we are adequately zealous about training before eating before you train. You know, and I think a lot of people have read some other stuff and listened to the other stuff that we've done and they're like, cool, you know, we're convinced. And then maybe they get a bit confused about what forms of exercise and what levels of intensity. Are gonna benefit from eating before they train and which ones you can probably not bother with. So when should I, what sorts of activity, what are the things that influence whether I could benefit from eating before I train versus times where I maybe don't really need to worry about it.


Jenna (27:15)
Yeah. So it comes all back to like we kind of talked about the energy systems and what happened, what substrates we use during different kinds of exercise, which will very much depend whether or not you need to eat or not. So if you come down, it comes down to intensity. So if you're doing any kind of high intensity exercise, you should eat before you train because we know that that has a bigger, we'd have a bigger requirement for energy and particularly glucose in those in those exercise sessions. How do you know what is intense? And this is it is relative to each individual as well. Like, you know, obviously we've got the black and whites of like going for a walk with the dog versus going to in CrossFit. You can clearly see that one is probably going to be more intense than the other, but it does also come down to the individual. So I always start off with the question of, well, how intense is your exercise? Can you maintain a conversation? Can you have this level of conversation? Then you probably don't need to eat before you train. The intensity is not there. If we're starting to get into the realm of exercise where you're maybe saying one or two words before you have to take a deep breath, you're not really wanting to engage in a conversation, cool. That's pretty intense. That would then warrant you need to eat something before you train. So, you know, again, going back to that kind of black and white, it's like, all right, well, if we're going for something like a gentle walk, I hate saying this, sometimes a yoga and sometimes a pilates as someone that doesn't do yoga or pilates, I still know that like, it can be intense. So that's why, you know, check in with yourself, like, am I working quite hard during this session or not? So, you know, if it is just, I don't want to say gentle stretching, but you know what I mean. You know where I'm not. I feel like I'm going to get all these DMs about me attacking Pilates and yoga. But if we're not having that intensity, then cool. We maybe don't need to eat before we train. If you want to eat before you train, go for it. Like it's not going to do you any harm, but it's maybe not as necessary. And especially if we have got body composition goals as well, where maybe we don't necessarily need those calories there. We could spend them somewhere else across the day.


Jono (29:16)
think that they definitely exist on a spectrum.


Jenna (29:41)
But yeah, definitely anything with intensity requires something to eat before you train.


Jono (29:50)
Yeah, yeah. I mean, I have clients who do like a 5k run faster because for them that's their zone to recovery. Easy kind of, you know, because they are very good runners. Yeah, but whereas apps, as you can see, probably, well, you probably hear from Jenna in my expression, like I joked to Kat the other day about it because I'm supposed to be doing a zone to run as part of my new program. And I like, I can't, if I'm running.

Jenna (30:17)
My body can't find zone two.

Jono (30:18)
My heart rate is zone three plus. Like there's no, yeah, I'm either walking or I'm zone three. And so, you know, that's the other thing, right? Like you've got to be sensible with your own fitness levels and your own where you're up to. Because just going, oh, you need to fuel for, oh, the run's only 3K. For someone that's an impossibly hard run and for someone else that's a warm up. But that's
cool. Like use your own filter.

Jenna (30:24)

Jono (30:46)
But yes, if you do do yoga or Pilates, just letting everybody know that jenna at bite me nutrition .com .au please send all hate mail and

Jenna (30:57)
Hey, if anyone wants to like give me a free yoga or Pilates session to give it a go, like I'm open to it. But you know, it's.

Jono (31:03)
Yes! That'd be epic. Yeah. Let's get that happening.


Jenna (31:08)
It would be a funny thing to watch my uncoordinated self trying to do that, but yeah.

Jono (31:14)
Yeah, well, no, I think there's like, there is the gentle and then there's like reformer and you know, there's all those levels in between. So again, be smart, be smart. Cool. I think we've covered everything that we need to cover.

Jenna (31:21)
Absolutely, absolutely.

Jono (31:33)
Nope, I've got no more questions for you. I think we've done a good job. You've talked about what fasting is, talked about whether fasted exercise impacts body composition, whether it impacts performance, and then what to eat, when to eat. Love it. Cool. So.Thank you again for coming on and opening your brain up and teaching us all about fast cardio. Hopefully, if anyone was on the fence, hopefully you are firmly off the fence now and you know why. It may not be the best idea for a lot of people in a lot of situations. As always, we will put those studies that we discussed in the show notes. I will send you, we'll put those posts that specifically talk about some of the things that you could eat before you train and some other things that you need to.No, and I'll also link you to Jen's email address. So again, if anyone is upset about her perspective of the intensity of yoga or Pilates, you can let her know that.

Jenna (32:38)
I'm just not gonna check my B -Mouth for two days. Let's...

Jono (32:42)
Just send them to me and I'll forward them on. No, actually throw myself on the bus. No, just DM them. That'll be fine. Cool. Awesome. Thanks, Jenna. Can't wait to chat about, oh man, I think we've got gym myths. We could do part eight if we're not careful, but we'll unpack some more of those next time we catch up.

Jenna (32:45)
Hahaha! Thank you.Yeah, sounds good.

Jono (33:01)
Cool, see you next time. Bye.