Transcription
Let's talk about fasted training, okay? And whether or not it indeed burns more body fat. And here, let's expand the conversation to include cardiovascular training. And of course, that's a vast space. Could be long, slow distance, could be high-intensity interval training, anything that gets your heart rate elevated deliberately for 12, uh, for 12 minutes or more is kind of how I put it.
Um, so let's be broad with what we're calling training. Mhm. Could be resistance training, circuit training, whole body, body part split, whatever. Let's, let's take all that and let's define the fast as not having eaten either for 4 hours during the middle of the day or for 8 hours or to 12 hours including sleep the night before. Right? Because people then say, "Wait, but I'm fasted cuz I don't eat lunch and then I..." Okay, it gets really murky and then, and then we could spend 26 hours here and we don't want to do that.
So assuming that one trains fasted, does one burn more body stored body fat in particular, or just more dietary fat if there's dietary fat circulating and available? Let's just say lipids. I think that we, when we hear the word fat, people think body fat, but there's also dietary fat. So could you please discriminate between those two? Yeah.
Okay. So picture this. Picture two people eating the exact same amount of exact same diet, identical diet by the end of the day. Same macronutrition, same food selection, everything is identical. One person, or one of the groups, let's say we're running a study, okay? One of the groups trains in a genuinely post-absorptive fasted state, 8 to 10 hours-ish, eating nothing. They will burn more fat during the training bout. Body fat, yes, they will burn more body fat. They will burn more intramuscular fat. They will just, their net fat oxidation will be higher than the group that has a, a breakfast. And the group that has the breakfast will essentially be, you know, burning their breakfast during the training. So yes, during the training, there is greater fat burning in the fasted group. But once again, we're looking at two groups who are consuming the exact same diet. So the group who consumed their breakfast is going to consume less stuff, less food, a one less meal in the later part of the day. So their fat oxidation is going to be higher in the later part of the day. And so it all comes out even by the end of the day.
So that is the kind of the big issue and the big principle with, with uh, fasted training having, yes, it does burn more fat during training, but you're looking at a snapshot of time within the course of the day. You're not looking at the course of the day. But you know what? This was a, a huge idea that persisted throughout the late 80s and early 90s, um, late, you know, even into the 2000s when uh, Bill Phillips came out with Body for Life and stuff. He was big on the fasted cardio and stuff. And so, um, these, this kind of lore is really cool if you know scientists who are able to rope you in and help, help you, you know, investigate this stuff.
So, uh, once again, you know, I got to give Brad Shenfeld a lot of credit. Uh, he wanted to test this hypothesis out. And so, um, we took college-age subjects, uh, women, and we compared fasted cardio with fed cardio. And the predominant lore at the time was, uh, the fat burning zone, right? So, we're, we're talking low moderate intensity cardio which they carried out for, um, a little less than an hour. And we compared immediate an immediate pre-prec cardio meal, which was a standardized, it was like a meal replacement type of thing with, um, a, uh, the same meal consumed postcardio. And then we measured body composition over it.
Hey, people criticize the study for being four weeks, but look, it's hard to run human studies. I've done it. It's, I've, I've, I've done a clinical trial in humans. I've, it's very hard to run long-term studies, especially in humans, especially when it involves nutrition and training. Yes, it's, it's brutal. So, uh, hat tip to you for tackling it at all. You're not going to catch any heat from me on the four thing. But I appreciate that you mentioned the duration of the study because, uh, in thoroughness, which you're characterized for, in thoroughness, um, people should know it. Yep. Yep.
So this is, uh, one of the only existing studies that looked at this question and and controlled, you know, hypocaloric conditions. Uh, I actually put together all the studies by hand for each of the subjects, kind of customizing it to their needs and making sure things were hypoc caloric, making sure protein was optimized. Uh, interestingly, there was no resistance training involved with the study. They were just doing their cardio. Uh, they, all subjects in both groups maintained their lean body mass, but both groups lost a significant amount of body fat. No difference in body fat reduction between groups by the end of the study whether they did their cardio fed or whether they did it fasted. And that's because we equated the total nutrition between the groups.
And you said again, the subjects were college-age women. College-age women. Yes. And what was the cardio? What was the workout? And the reason I'm asking is that it's impressive that they all lost body fat as long as they ate the, uh, appropriate amount of calories. Didn't matter when they distributed those calories relative to the exercise and they maintained lean body mass. Um, and if they weren't doing resistance training, um, I'm impressed that the cardiovascular training was sufficient to allow them to maintain lean body mass. What was the cardiovascular workout?
It was low, moderate intensity, um, what, um, might be called zone 2 type of type of cardio where you can still hold a conversation, but, um, you know, it's not necessarily a waltz. And so the whole idea was to be in the fat burning zone. We want to exploit the whole fat burning zone concept, uh, to keep the intensity low moderate so we can give the fasted cardio condition a chance to show whatever magic it might have. And so we didn't see that magic by the end of the trial. Um, and yeah, uh, but here's the, the, the practical takeaway from that is number one, we didn't see a bunch of lean mass loss in the fasted cardio group because there, there's this lore saying that, hey, you better not train fasted no matter what. You better, you better not do cardio fasted because you're going to lose muscle. Well, they didn't lose any, any lean body mass.
And, um, when you form practical takeaways from the findings, we can say that if you prefer to train fasted, uh, and you just feel better doing your cardio in a fasted state, great, do it fasted. If you can't stand doing fasted cardio and you'd rather have a, a breakfast beforehand, then go ahead and do that. Just know that that's not going to necessarily hinder your fat loss efforts as long as you're net hypoc caloric by the end of the day or the end of the week. And I mean that, those recommendations can change with the type of cardio you do, especially higher intensity stuff or certainly competitive types of sports that involve, uh, you know, endurance performance elements and stuff. But that's the, the takeaway from our study that fasted versus fed cardio doesn't matter. Do it based on personal preference.
I love it. After so many years of trends coming through, train fasted, don't train fasted. It, it seems like, as with protein, what I'm learning from you is that there's a lot more, uh, flexibility in time than we might have once thought, but that the absolute calories of course matter. Prioritizing protein matters. And I'd like to, and that you still have to train. You got to do something. And, and, and can I add this because I know you'll appreciate this? I'm not going to cherrypick our study and say that this is the end all result that that is gospel. So there's actually a, a later meta analysis a few years later by, I think it's Hagstrom and Hackit, who looked at fasted versus fed training and they overall found no significant differences or significant advantages in terms of body compment fat loss in the fasted versus the fed conditions as long as total nutrition is equated between the groups.
Love it. This is music to my ears and I'm sure it's going to be music to everybody's ears because it just says there's flexibility. There's flexibility. There's flexibility and life is complicated. So more flexibility is pointing too for if you're looking for magic, if you're looking for that special little thing you can do that, well, maybe the magic is in the training consistently, um, the nutrition including protein, and the knowledge that there's flexibility. I have this saying in my mind lately that the things that make 90% of the difference, like sleep, exercise, nutrition, light, stress management, relationships, etc. in our health are the things we have to do 90% of the days of our lives. And that's why there, there can continue to be so much discussion around them. This is why it isn't just like, here are the basics, okay, you're done. It's because the things that we have to do every day, we often have to be reminded to do every day.
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