Transcription
Okay, all right. Yep. Well, let's, uh, let's dive right into the metabolic classroom. So today, our topic is, "Do low-carb diets spike cortisol and reduce muscle mass?" So, Dr. Bickman, we're going to try to turn the time over to you. And, uh, I think we, we get a lot of questions about cortisol. We sure do. Yeah, yeah, yeah. So that was the impetus for this study, me pulling up this study. And I'll actually end up referencing another study as during the course of this discussion. But briefly, let's talk about some of the reasons why people are pointing the finger at cortisol, especially in the context of a low-carbohydrate diet.
So, of course, if you start cutting out carbohydrates from your diet, indeed, what happened to this study? Where it goes from an average, you know, the average person is eating about 50 to 60% of their calories from carbohydrate. When you go to a low-carbohydrate diet, you're cutting that down to a fifth or a sixth or, you know, a tenth of the amount of calories. So in this study in particular, they went from about 50% of their calories from carbs down to 8%. So, which is pretty typical. Um, when you adhere to a low-carb diet, of course, if you start putting less glucose into the system, the body starts making more. There are these natural counter-regulatory mechanisms, which is why glucose levels stay normal. If you take someone who has normal glucose and they adopt a low-carb diet, their glucose will stay normal. It will continue to hover around 80 milligrams per deciliter. It stays normal because the liver begins making more glucose to make up for the lack of glucose coming in.
Now, this is relevant to cortisol because there are a small little cluster of hormones that will stimulate the liver to turn on this release of glucose. Growth hormone will do some of this. Cortisol will. And epinephrine will. And glucagon. Those are really the main four that are going to be stimulating the liver to make more glucose. And of course, there's a reason for that when that happens. So, there is a lot of suspicion that if you adopt a low-carb diet, one of the ways you're keeping your glucose normal is because the cortisol is coming in and it's pushing the liver to continue to make glucose.
Now, the glucose maintenance effect of cortisol is only one. In fact, it's maybe the most benign. Cortisol is a hormone that can, it'll basically destroy everything in order to increase glucose, including stripping proteins from things like your muscles and your bones to get those amino acids to send those amino acids to the liver and then tell the liver to convert those amino acids into more glucose. And that's why people who have actual endocrine diseases of elevated cortisol, like Cushing's disease, if you guys have heard of that one. Yes. So, Cushing's disease is disastrous, where they have this cortisol-spiking tumor, and they start to waste away with regards to their lean mass, including their skin. Their skin starts to get weak, and they get all these like stretch marks because of how compromised the skin is, all for the sake of getting to these proteins, giving the amino acids to the liver to make new glucose, in addition to reducing the immune system as well and changing the way the body stores fat. Suffice it to say, cortisol is a hormone we do not want elevated for very long. So, it's reasonable to be concerned. Is a low-carb diet going to spike my cortisol?
Well, there's one main study I want to reference, then there's a second one that I'll just highlight that I, I wish I would have planned a little better to focus on more, but I'll mention it. These are the two studies I've seen that look at cortisol in average people, not in the context of say, an exercise type study. So, some basics on this study. Um, the title, you guys will have this. We'll share the title and, uh, maybe a link. Is that right? It's "Body Composition and Hormonal Responses to a Carbohydrate Restricted Diet." This is some of the work from the legendary low-carb scientist, Jeff Volek, while he was at Connecticut. So, in this study, the first point, which I think is interesting, they, they have a control group and then the diet group put on a low-carb ketogenic diet. The group that was put on the low-carb ketogenic diet, they volunteered for the diet. So, it was self-selected. So, strictly as a scientist would look at that and say, well, that's a weakness. It wasn't randomized. It should be randomized. But then the pragmatist, the coach, the wellness owner, center owner says, well, I'm going to get much better adherence if the person's volunteering to do it. There's something that drives them to want to do it. This study relied on volunteers. They volunteered for that, which does introduce perhaps a problem from the scientific side. But again, the pragmatist in me says, well, that's more, it's more real life, and they're going to adhere to the diet better because they wanted to do it. Yeah.
Now, they were all considered healthy going in, um, in, in same body weight, and we'll get to that in a moment. Um, some of the study, the subject description, well, that's about it. They're, they're all kind of normal weight, healthy guys in general. Um, the low-carb diet, they transitioned. I mentioned the carbohydrate transition. They went from around 50% down to 8%. And then on Table 1, where they described the macronutrient breakdown they were eating, they went up to eating about 170 grams of protein and about 160 grams of fat. And there we go to that magic one to one, um, by mass ratio. By mass, the fat and the protein is about one to one, which by percent of calorie ends up being 60% fat-ish, 30% protein. And that's, that's, that's a great range. And interestingly, um, sort of conventional keto thinking, um, worries about protein because of the insulin spike. Interestingly, in this diet group, they were eating twice as much protein as the control group, twice as much protein. And yet their insulin, if we go to Table 3, the insulin in the diet group, the low-carb group, it changed from around 23 picomoles, which is high, down to 15. So, a significant reduction. Whereas in the control group, which is eating half the amount of protein, it stayed in the low 20s. It didn't change at all. In fact, it actually tended to go up a bit, but it was, it was in the margin of error, so it wasn't a significant change. So, that is one interesting takeaway. This study, they were eating twice as much protein, but in the context of significantly less carb, and the insulin went down significantly. Yeah.
But we were taught the very beginning that, I mean, this 80, 15, 5. Yeah. And we're not, we're not teaching that anymore. No. In fact, and really, where I, totally appreciate that became kind of a dogmatic perspective. And yet, when you really look at the low-carb diets in much of the research, it, it really never got there. It really never went there. It was almost always this kind of one to one or 60, 30 split by mass or by calorie respect. Not to throw Volek under the bus, but isn't that what they were teaching in their book, "Low Carb"? They might have. Yeah, I think that's right. Yeah, yeah. But, but their research here, this is one of several from Jeff Volek's lab where it was this kind of one to one. It was your talk at Breckenridge that that changed me. Well, hey, you're welcome. You were right there, man. You were there for the magic. You saw it happen. So, anyway, that's an interesting takeaway. So, one takeaway, unintended from this study, don't fear protein because even if you're eating twice as much, and they were literally eating twice as much as the control group, their insulin still dropped significantly. So, exactly. Don't, yeah, don't immediately just think protein is going to be a problem.
All right. Now, another takeaway before I get to the gist of it all, which was the hormone changes. They looked at differences in body mass. Cortisol will reduce lean mass. It will literally strip the proteins from muscles and bones, like I said earlier, to get those amino acids to feed the liver in stimulating new glucose production. So, you'd think, well, if cortisol is going to be up, then they ought to be losing muscle mass. And on Figure 1, if any of you guys are able to follow this, they found that the body mass didn't change significantly in the control group, which is good. They didn't want them to change. In, despite eating roughly the same amount of calories, though, the, the body mass did significantly change. It went down by a little over two kilograms in the diet group, in the intervention, the low-carb group. Interestingly, and evidence that we can never just look at body mass, total, the sum of it, and know what we're, know what's happening. We can't just look at the scale. They found that fat mass actually reduced by over three kilograms in these six weeks, and lean body mass, so muscle and bone mass, mostly actually went up by over a kilogram, and it was a statistically significant difference. So, this idea that I'm going to adopt a low-carb diet and the lack of insulin or the, you know, whatever it's going to, it's going to make me lose lean mass. I'm not going to be able to either retain my lean mass, let alone build it. Well, they built it. They, they added a kilogram, so a little over two pounds, um, just in these six weeks without reporting any significant changes in the exercise. So, more evidence that some of what we think we know isn't really the case.
Now, Ben, we can show you hundreds of clients that at Instant IQ and Elevate that we've done. Rarely do we see a decrease in muscle mass over months and months and months, and this is even in the absence of them getting into the gym and doing squats and deadlifts, and they're losing 30, 40, 50 pounds of fat. Yeah. And you think just because of decreased mass, yeah, they would lose protein, and they're not, or muscle mass, they're not doing it. Yep. It's just staying steady. I mean, initially, we'll see a little bit because it's probably a little bit of water and body is a little bit, you know, just, yeah. And they used a DEXA in this study, which is a much, yeah, that's one of the gold standards, really. We're just not seeing it. And they also looked at, lastly, on Figure, um, one, they looked at bone mineral content, and no change there. There was no loss of bone mass, which is meaningful because if there's someone listening to this who is beyond middle age, especially a woman, and you're thinking, well, I want to go on a low-carb diet because I want to lose weight, the fear with conventional dietary intervention with, you know, low-fat, calorie sure, you're losing weight, but you are losing bone mass. As in fact, a significant amount of lean body mass. This study suggests that that doesn't have to happen. You can lose fat exclusively while retaining bone mass and even increasing your muscle mass within this six-week study. So, don't assume you, you have to have that negative, that there's going to be an unintended consequence of losing lean body mass, muscle, and bone as you lose the fat mass. It doesn't have to happen that way.
I got a question for you. Osteoporosis and osteopenia, did they, is that affected by insulin? Oh, yeah, most certainly. Um, yeah. So, insulin is, insulin wants to tell things to grow. But bones can become insulin resistant. Joints can become insulin resistant. One of the interesting things about the joints is that we have to have the joints making this fluid to kind of keep the joint greased, and those cells that make this fluid are, are very poorly vascularized. They don't get a lot of blood, and so they, they don't get to see a lot of oxygen. And so they're, they're relying more heavily on a process called non-oxidative glycolysis. They need to use glucose, and a lot of it. And if they become insulin resistant, their access to glucose becomes compromised, thereby compromising the joint because they don't have enough energy. That's interesting. Yeah.
All right. Now, last, last bit here, and then I'll be done. Um, the, the hormone pattern, and that's Table 3. So, they found that, I already mentioned a significant drop in insulin, um, in the low-carb group, despite eating twice as much protein, and they were eating three times more fat. Um, glucagon actually tended to go up a little bit. It did, it did not reach statistical significance. The error was too much, um, but it tended to go up. Testosterone didn't change. Um, and then I don't want to get to cortisol yet. So, IGF-1. Remember, these guys were eating two times more protein, right? And the typical thinking is, so IGF-1 is relevant because people who don't like protein or who are afraid of dietary protein, they say the protein is going to cause cancer, and that's going to be because you get an increase in IGF-1, because IGF-1, insulin-like growth factor 1, is a factor that is implicated in facilitating cancer growth. They were eating twice as much protein, and their IGF-1 didn't change. It literally didn't change, not, not even one single value point throughout the length of the study. And then let's get to the cortisol, finally. One thing that was so interesting here, well, first of all, cortisol did not significantly change and tended to go down by a lot, actually. But the, the standard error was massive in this study, which I think, um, creates a bit of a problem. I bet they had. And so the standard error, basically, what they found was that the, that the average was 618 nanomoles of cortisol in the blood, and yet the standard error of the mean was over 300, so a huge range, which probably means the majority of the study subjects were in one area, then you have an outlier or two people that are just really pushing it to the extremes. And so within that group, there's a tremendous room of error. That's the standard error of the mean. So, it was huge, but the sum of it was no significant difference. It did not go up, and in fact, tended to go down, but it was not statistically significant. So, directly challenging the idea that a low-carb ketogenic diet is going to stimulate your cortisol.
Now, I told you guys I was going to reference one other study. Let me just mention it quickly. This is a study published last year, actually in 2019, in the Journal of Nutrition Research. The PubMed ID, and you guys can look it up with this, it's 30803508. This, in contrast, looked at more at obese humans and put them on a low-carb diet, and there were tremendous number of takeaways, including incredible weight loss, incredible improvements in lipids, great reduction in insulin. They did find a difference in cortisol. And so, let me briefly share that. From baseline until week two, the women, the female group, not the men, the women had a statistically significant, marginally, it was less than 0.05 but above 0.01, so marginally, but still statistically significant increase. Then by week eight, it was gone. Wow. So, week two, not in the men, though. No significant differences in the men. In the women, in the female group, at week two, there was a slight, and I mean like a tenth of a point, in the cortisol. It was slight, but it, so whether it's meaningful or not is debatable. It was statistically significant at week two, but then it was gone at week eight. So, maybe is there some truth to the claim that a low-carb diet will raise your cortisol? Maybe in this one study, in the women-only group, at week two, there was. But as it continued, it was gone. And that might be just reflective of this transition phase. You've done something very different, and maybe you do need a little more of those gluconeogenic hormones, like cortisol, for example, to help the liver keep the glucose normal in this transition phase, and then you've adapted over the next few weeks, and everything's gone back down to normal. So, that's my takeaway. Maybe there's some truth to this, but my strong suspicion is that over the long term, there is no validity to the concern that a low-carb diet will spike your cortisol. Huh. Cool.
Specific questions? Uh, well, I was going to point out that there weren't any women in the first study. So, I'm glad you brought that up in the second study because to me, that makes it a little bit more valid. But I agree. The thing that I thought was interesting, kind of side note to the cortisol effect, was we preached this a lot at Elevate when worked, when we're talking about insulin. When you only look at your body weight and how that's changing, you just don't get the full story. And this study did a great job of showing that if you're losing fat and gaining muscle, you're going to see huge improvements in your body composition without ever noticing change on the scale. So, we have lots of people that will say, you know, last time I lost weight, it took me 20 pounds to change whatever, two dress sizes. And now I'm changing dress sizes in 10 pounds. Like, what gives? And that's really what's happening is you're changing body composition. Yeah. Well said. Yeah, I know Rich has complained about dress size. Hey, don't tell anybody, it's our secret.
Do you get other questions related to this from clients that come to mind that we might want to pose before we leave? Is the cortisol concern a common one that you guys see in the gym? I see it in social media. Yeah. Enough. We don't. I mean, most of our clients come in that don't have any. They're coming from physicians, and their type 2 diabetes. They're not worried about cortisol. Yeah. Right. That's the least. If they're worried about, you know, their blood sugar. And so, I rarely get the cortisol question. Sometimes you get it if somebody's blood sugar isn't starting to, you know, see control as they get rid of carbohydrates. People wonder what that is. And it can be a stress response, but it's not coming from the eating or the lifestyle, the diet. Yep. Great.