Carb Cycling, Workout Carb Timing, and the Menopause Carb Myth
It turns out that carb cycling does NOT improve fat loss or your metabolism. But does it have other benefits?
You've heard you should load carbs on lifting days and cut them on rest days, especially after 40. Where did this idea come from?
I'm breaking down the one study that comes closest to testing carb cycling and what happened when a second group of researchers reanalyzed the data. You'll also hear why the insulin and fat storage argument doesn't hold up, what one study found about insulin sensitivity after menopause, and the number of hard sets that determines whether carbs before training do anything for you.
Where carb cycling comes from and why it spread beyond bodybuilding
The Campbell 2020 refeed study (and later reanalysis)
Why insulin and “storage hormone” arguments do not predict fat loss under matched calories
What leptin and metabolic flexibility claims get (partially) right
What research suggests about menopause, insulin sensitivity, and body fat as the driver
How to set weekly calories, daily protein, and fiber before worrying about carb timing
When pre-workout carbs matter most, and fed vs. fasted training
Why underfueling and low-carb patterns can backfire for recovery and your relationship with food
If you want to stop earning your carbs and put them where your week needs them, hit play.
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Timestamps:
0:00 - 4 carb questions from the community
3:14 - Where carb cycling came from
7:22 - The refeed study and later reanalysis
11:59 - Insulin, storage, and a metabolic ward
13:16 - Leptin and fat-burning arguments
15:52 - Can a structured high-carb day be worth it?
17:37 - Does insulin sensitivity drop at menopause?
20:31 - Carb cycling in your actual week
22:42 - Complex carbs on lifting days
24:32 - Eating before and after you lift
27:07 - Bonus: hard sets and carbs before training
Episode Resources:
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4 carb questions from the community
Philip Pape 0:00
What is the deal with carb cycling? Maybe you've been told to load your carbs on lifting days and pull them back on your training days. Maybe you're over 40. I want to go through what the research actually says. Today I'm answering four listener questions on carbs and carb cycling. I'm going to show you why the studies people cite as proof are often testing the wrong thing that they're claimed against, what the evidence says about carbohydrates and menopause, and how to think about pre and post-workout carb timing. Welcome to Wits and Weights, the show that puts a popular piece of fitness advice under the microscope, finds a hidden reason it doesn't work, and gives you the deceptively simple fix that does. I'm your host, Philip Ape, and today's episode came from several questions from our community and from our members. Sonny, Sonny, shout out to you, Sonny, who is both in our Eat More Lift Heavy dialed in as well as in our Facebook group. And I'm quoting him: How can we use carb cycling in our everyday lives? And is there data on this subject? And I told him as a reply that the short answer is it's always a scheduling and preference thing, more than a physiological thing. But I did want to go and review the research and answer it properly on the show today. So that is what this is. Sonny, thank you. This turned into actually a much better episode than what I expected when you asked it. So stick around to hear it all. Uh then he followed up with a second question, which is that he's been hearing that one technique is just include complex carbs on lifting days. And then Lisa chimed in. Shout out to Lisa in our Facebook group. And she said, Hey, what do we eat and when before a workout and after? So I'm kind of combining these all into one episode today. I then pulled in a fourth question that comes up all the time, which is whether you should go lower carb on rest days once you're in perimenopause, because you've supposedly become more carb intolerant. Now, many of you listen to the show know that a lot of these carb uh claims are just that. They are myths, but there are some that are more persistent than others, and we need to address them. So, four questions that all rest on the same premise or the same assumption, which is that number one, carbohydrates are as important as we think they are. And number two is that where you put them across the week changes what happens to your body. And then I want to want you to stick around to the end because I always leave you something helpful at the end to take away from the show. I'm gonna show you how to tell whether eating carbohydrates before you train is actually going to do anything for your performance. It's a little bit of a rubric or heuristic you can test on yourself, or whether it's just not worth trying to move things around in that way. So we are gonna go through where did carb cycling come from, what the evidence base consists of right now as we know it, then the mechanism, meaning insulin and fat storage, the arguments around that, whether that has any merit. And then the menopause piece here, which is what many of you are concerned about as well because of what's being talked about online. And we're gonna give practical answers to all of these. All right, let's dive into it.
Where carb cycling came from
Philip Pape 3:14
Carb cycling. If you've never heard of carb cycling, it is the practice of eating more carbohydrates on days that you train and less on days that you don't, usually while keeping protein high and consistent, maybe fats are roughly similar, and staying in some kind of deficit. It often goes along with a calorie deficit, but some versions are whether or not you're in a deficit or maintenance. Some of them are the opposite, like for the training and the rest days. Some have high, medium, and low. There's all different permutations of this, just like there are with fasting and everything else. Now, where did it come from? Is mainly from bodybuilding contest prep, where people are manipulating carbohydrates and water, usually in the last week or so, to change how they look on stage. Now, that's a real thing that you can do is manipulate your carbohydrates, your sodium, your fluids to change how you look. And a lot of this stuff kind of filters down into the common, you know, vernacular, if you will, or onto forums or things like that. And it gets blended in or confused with other movements, let's say, or tribes in some cases, I say with a little bit of derision, but like the low-carb movement. And then it gets combined with, say, the endurance nutrition information about glycogen. And by the time it's kind of all put together, it's almost like this big package on here's a diet, dieting protocol you can use, right? And I say it that way with, again, with a little bit of snark, because I've been there. I've been there where I've taken this piece, this piece, this piece, starts to put them together. Now you have a nutrition approach, but the approach is kind of a fra combination of fragmented or disjointed pieces that don't necessarily work together. Or, andor pieces of them that are not supported by actual physiology, like actually how the body works. And, you know, if you think about it, we all want structure. This is what, this is why diets over the years, why you can go into like a bookstore or online, but it's easier to see physically in a bookstore. You go to the section on with like the diet books and you just see tons of them. Each one is promising like the simple structure and approach, right? From keto to carnivore to low fat to weight watchers, all of it. And carb cycling is fits really well in that um model of a structured approach. But Sonny asked, does it work? Like, is there data behind using it? So what I did is I went looking for randomized controlled trials, or Lane Norton always jokes, is like human randomized controlled trials that tend to isolate one variable that we care about. In this case, what do we care about? Well, we care about the keeping the calories the same and the protein and fat the same, but distributing your carbohydrates differently. Now, I will the caveat here is there is a concept of calorie cycling, but oftentimes we it's a proxy for carb cycling because if you're holding your protein fairly steady, the thing that changes the most is carbs. So just to put that on the side. So you have to have a control group that has the same carbohydrates every day versus a group that cycles it in some other way. And then you measure what happens, like what happens to body composition or other factors. The problem is I can't find studies like this. And I think that's actually the case, that there is weak evidence for carb cycling. And what I mean is the studies are often small or short or in the wrong population. And in this case, there doesn't seem to be any at all, like no direct trials. There's a review from 2025 on carbohydrate cycling for contest prep. And I am gonna come back to that one, but it's interesting for a different reason, teaser. But there is no randomized trial that tests what we are asking about. Now, does that mean it doesn't work? Of course not. I don't want to be one of those like science-based lifters who, you know, absence of a trial is evidence against this thing working. Of course not. I don't want to be that guy. But it does mean if somebody says carb cycling is evidence-based, you need to ask them, like, what evidence are you talking about? Okay, let's go through the studies that people will bring up because this is kind of the counterpoint that I want to address. The biggest one is a trial from Dr. Bill Campbell and colleagues in 2020.
The refeed study and later reanalysis
Philip Pape 7:22
Again, love Bill Campbell. I probably say his name like every other episode here. He's one of the better science communicators that work in this space. That's why. You know, he has he has a whole lab devoted to this kind of stuff. And that study took 27 resistance trained people, average age of 25, and they went into a 25% calorie deficit for seven weeks. One group did two consecutive high carb days, followed by five restricted days every week. So that's like a weekend refeed, if that sounds familiar. And so if you look at that structure, it is also a form of carb cycling. Like it's the closest thing we have to carb cycling in the literature, like that. The conclusion that was published was that the refeed group preserved more fat-free mass and more resting metabolic rate. And that's a great result. And everybody cited it, including myself. But then a group of researchers, Payos and Brown and Vorlin and Allison and Sainsbury, they reanalyzed the shared data and they did it open in the open. And they ran it as a between group analysis. When they did that, the difference in fat-free mass disappeared. The difference in resting metabolic rate disappeared. All that was left was the dry fat-free mass mass, which is like a component measure. So the original finding didn't really survive the reanalysis. And Campbell, you know, he admitted it, right? So that's awesome. And if you go back and look at my uh episode I did a long time ago about the weekend diet, I cited that research as potential support for that. And I believe I equivocated a little bit in the episode. I I'm pretty sure I did. I didn't say, like, oh, this is absolutely 100% true. It was more of, hey, here's a practical way among many to use a nonlinear approach and switch around your calories for practical purposes because a lot of us like to eat more on the weekend. And so if it helps you stick to your diet, go for it. And it may have this other physiological benefit, which now we've walked back and said maybe it doesn't have that physiological benefit, which is fine because it still may have a practical benefit. And then on recent episodes, we've talked about the matador trial, which is two weeks on, two weeks off, but that's not really the same as like carb cycling where you do it within the week. And then the ice cap one as well, that I think I've talked about where they did intermittent restriction versus continuous restriction. And again, I mentioned these because the idea of carb cycling is similar to the idea of intermittent restriction, in that some days have higher carbs that are probably close to maintenance, and others are more of a deficit. So, in a sense, that is what you're doing. Then there's a meta-analyses that pooled 28 trials. They found a body weight difference of 0.42 kilos that favored uh intermittent approach, and it was not statistically significant. A small fat mass difference of 0.31 kilos, also not significant. And if anything, slightly more fat-free mass laws in the intermittent groups. So you can go through study after study after study and you really don't see any obvious result that says, oh, yeah, you definitely you need to carb cycle for X, Y, Z reason. And this is going to give you a benefit in fat mass or lean mass or metabolic rate or any of these things, right? The ones that come closest that to have a result at all tend to be a null result or a, yeah, there's a small difference one way or the other, but it's not statistically significant. So, okay, why does the idea persist though? Like calorie and carb cycling. And when I say persist, I mean I see people ask about it occasionally, and I generally just give a quick answer like, it's yeah, the evidence isn't really there. Go ahead and just use it if it's if it helps you practically, right? But but I can say the same answer to anything that helps you because it's practical. You know, if it feels good, if it helps you stick with your diet, et cetera. So the mechanism is very convincing. And this is the thing with mechanistic research and also looking at mechanisms in our body and saying that, oh, well, if the mechanism works, let's extrapolate it to the whole body level or the system level or the person level, and then we can say that that works. But that's not always the case. So the story goes like this carbohydrates raise insulin. Insulin is a storage hormone. So if you eat carbs on a day that you're not training, the carb has nowhere useful to go and get stored as fat. Whereas on a training day, your muscles are ready to tick it up, right? That glucose sink. And you've heard that a lot. And it sounds reasonable, it sounds intuitive, and it's wrong. It's wrong. We actually have the study that settles this, I think. Kevin Hall, good old Kevin Hall, ran a metabolic word trial of 19 adults with obesity. They were locked in a facility,
Insulin, storage, and a metabolic ward
Philip Pape 12:46
all their food was controlled, their protein was controlled, same calories in both conditions. One group, they restricted carbs, the other group they restricted fats. Now, if insulin drives fat storage, you would expect the group that restricts carbs should come out on top, right? This is like the essence of low carb. Well, the carb restriction group lost 53 grams of body fat per day. The fat restriction group lost 89. So cutting carbs under identical calories actually produced less fat loss, not more, less, not more. And this is the tightest kind of control you'll ever get in nutrition research. These people couldn't cheat. They everything was controlled. Okay. And whether you want to like rely solely on one study, which you never should, it goes the opposite in what people often claim. And, you know, my theory on this is that the thermic effect of food is higher for fats and carbs. So if you're eating exactly the same calories, but you're having more fat versus more carbs, you might actually burn a few more calories. In other words, your expenditure is a little higher, putting in you into a little bit bigger deficit, which actually benefits eating more fat than carbs, right? But that argument alone is for me never enough to like alter your entire macro balance. Then there's the leptin
Leptin and fat-burning arguments
Philip Pape 14:03
argument, which says that high carb days restore leptin and thyroid and bring back your metabolism. And there was a real study here by Dyrl Wanger and colleagues. They took 10 lean women with three days of carb overfeeding. Their leptin went up 28%, and their 24-hour energy expenditure went up 7%. So sounds great. But their basal metabolic rate was not affected. So if the effect is real, it's short-lived, it goes away within a day or two of returning to your normal intake, and it doesn't basically change your metabolism at all. In other words, it just goes back. It's like this temporary thing, and it's probably temporary because you're eating more food for those couple days. So that's all it is. It's just literally following your food temporarily. Okay. The last mechanism here we have is metabolic flexibility, which says, hey, low carb days, train your body to burn more fat. Now, there's a piece of that that's totally true. Your respiratory quotient changes when you have low carbs and you do oxidize more fat on those days. But burning more fat is not the same as losing more fat. And, you know, I use the word burn loosely here. What matters is net fat balance over the days and weeks, not what fuel you happen to be using at a specific time during that moment. What I mean by that is when you are low carbs, your body's now gonna just use fat, but you're either in a deficit, meaning you're eating fewer calories, and that's the reason you're losing fat, or if you're eating the same amount of calories, it's because you're eating more fat and it all nets out. The point is you're either gonna burn fat or carbs, but at the end of the day, it comes down to calorie balance. It really does. At the end of the day, it comes down to calorie balance. And if we go back to the trial we just talked about by Kevin Hall, it demonstrates exactly that. Okay. In fact, it showed again the opposite almost that people that burned more fat because they were eating less carbs, they actually lost less fat. So whether you want to take that to the bank or just say, well, at the very least, it's equal, you definitely can't go beyond that and say, well, low carb burns more net or causes more fat loss. Now, the part I find really funny is that the the 2025 review on carb cycling for contest prep, the one that I said I'd come back to earlier, that's seems to be very favorable toward carb cycling, explicitly says in the review that net energy balance governs fat loss and that carbohydratability just governs performance and appearance. Well, they're basically conceding the argument that people are trying to make with carb cycling, right? Right in
Can a structured high-carb day be worth it?
Philip Pape 16:39
the paper. So if you want to use structured high days and there are good reasons to, which we're gonna talk about those reasons in a second, mainly for refeeds and diet breaks. I have a free guide for you that goes into it. And I'm mentioning it now because it could be interesting to download and go through it as we go through the practical stuff. Following the next section on menopause, we're gonna get into the practical stuff around refeeds. Specifically, not so much carb cycling per se, but refeeds and diet breaks. So use a link in my show notes or go to witsinweights.com/slash free, and you'll find the refeeds and diet breaks guide in there. I'm gonna put the link in the show notes again, and you can just tap it. But it's my free refeeds guide. Um, and that's a tool that I definitely get behind for the reasons we're gonna talk about in a second. All right, so that's the general state of the literature to my friend Sonny and everyone else who's asking about this. But there is one more question we got about whether you should go lower carb on rest days now that you're in perimenopause, because you're carb intolerant. So I just want to address the carbon tolerance piece. And maybe it's not even a perimenopause thing. Maybe it's just in general, I'm older and I think I'm less carb tolerant. And it's usually phrased in the context of my hormones have changed, my insulin sensitivity has dropped, so I can't handle carbs the way I used to. And I also see this in the, you know, women over 40 should be going low carb. Please, please don't listen to these people because they don't know what they're talking about. But let's take the first claim on its own terms. Does insulin sensitivity actually decline at menopause, independent of aging and independent of the fat you gained? Well, we have a study on this using the hyperinsulinemic euglycemic clamp,
Does insulin sensitivity drop at menopause?
Philip Pape 18:24
which is a gold standard measurement. Okay, it's not a fasting number, it's a clamp. 101 postmenopausal women age 57, they found the relationship between esterdiol and insulin resistance was fully explained by body fat mass. It was fully mediated, meaning the estrogen change was not causing the change at all. The change in fat mass was causing the change in insulin sensitivity. And then Lovejoy and colleagues ran a longitudinal study. 156 women who started out premenopausal, 47 to 52. I've mentioned this study before, and they followed them through the menopause transition. And yes, menopause itself was associated with gaining total fat and visceral fat specifically. That's real. I covered that on a recent episode, but they found no menopause-specific effect on insulin resistance. Um, and again, you know, I mentioned a longitudinal claps study. Look it up so you know what that's about. But the driver here appears to be body composition. Wow, what else is new? If you've been listening to wits and weights for any length of time, you understand how important the importance we place on body composition driving some of these things, which means it's in our control rather than something like estrogen. Now, while we're in the same kind of family of claims, let's talk about your resting metabolism. Herman Ponser's group that I've talked about recently with doubly labeled water, where they see that energy expenditure, your resting metabolism, is pretty stable from the age of 20 to 60 without any change for menopause. And then other research we see that shows that energy expenditure is stable once you account for fat-free mass and fat mass, you basically lose the premise or assumption behind why people suggest you need less carbs, right? Where you're like, well, okay, my insulin sensitivity is lower. Therefore, I need to restrict carbs and restrict them on rest days, for example. So you've got like a chain of logic that just doesn't work. And guess what? The intervention that's actually supported by the evidence for insulin resistance as we get into our 40s and 50s, men and women, is what? Reducing your fat mass and using resistance training and moving more, which we talk about on the show every single episode. Now, the biggest problem with all of this is probably there is a gap in population. Not one of the trials I've described was run in perimenopausal or post-menopausal women, other than the study, like like I mentioned, Lovejoy looking at pre-to-postmenopause transition. But on this other stuff around cycling, is what I'm talking about. You know, in Bill Campbell's group, they were average age 25. He works with a lot of college students. Ice cap was 28.7, the women's diet break trial was 23. Matador was men with obesity, right? So all these studies, they haven't even been looked at in that population anyway. So, what should you actually do? This is the fun part of the episode. We get to the fix. So I'm gonna address each of the four questions quickly as to
Carb cycling in your actual week
Philip Pape 21:18
here's the answer, here's what you do. Sunny's first question how do you use carb cycling in everyday life? My answer, and this is the answer that has the research backing it up, is that you set your weekly calories and your protein first based on your goal. Are you in a deficit? Are you at maintenance? Are you building muscle? You keep your fiber reasonably steady, which should be fairly high to begin with. If you're not there yet, that's a good thing to work on. So probably 25 grams or more for women, 35 or more for men. And then fats and carbs are highly, highly flexible. And you can put them wherever your schedule and training want them. And I would usually default to the same every day. But then I would start to tweak it based on how you feel, practicality, days that you like to eat more. For many people, that's the weekend, has nothing to do with their training schedule. Sometimes it's when you're not training. So if it's on the weekend, because that's when you go out to eat, maybe that's when you want your carbs, Sonny, or anyone else listening. Distribution of carbs and fats is a scheduling tool. I do like to keep protein steady every day. And I don't like people to have more volatility than they need because for some people, having too much volatility, too many high and low days, it in and of itself could be a negative in different ways. It could be a negative in how you feel or your sleep or like your metabolism, things like that. But it's very individualistic. What it is not, Sunny, and everyone else listening is a lever. For additional fat loss, for better recovery, for better performance, for better metabolism. Again, unless you individually respond in a way that it seems to move those things, which I'm not saying it isn't, but the evidence as a whole at a population level doesn't support that. Which is actually a good thing because it means we don't have to do all these weird little protocols. Just do what makes most sense practically so your life is as easy as you can make it to still hit your goals and you're not stressing about it. Now, Sonny's second question about complex carbs on lift days. I'll say there's two parts to that. So concentrating carbs on rest on training days versus spreading it evenly at the same intake, you know, has not been shown to change body composition, which we kind of covered that. But the complex versus simple carbs distinction, once you match total carbs and match fiber, doesn't matter either. What
Complex carbs on lifting days
Philip Pape 23:29
I think people are usually talking about or or capturing, I guess, when they say complex carbs is fiber and satiety because you're eating more whole foods. And it's not always complex carbs either. You can be, you can fill yourself up even on some simpler carbs, depending on what it is, but that conversation is a separate conversation. But if you're eating oats and potatoes and beans, great. That's what I want you to do. Just don't believe that the like the structure of the starch, because it's a complex carbs, is moving the needle in any particular way for fat loss, body composition, metabolism. It just tends to be that people who have more simple carbs and fewer complex carbs end up eating more calories, for example. Or they end up not being as full and then they eat more calories. Or they're not as full, so they're hungry, so then it makes them stressed and miserable, and then they don't train as well. Like you get what I'm saying. Now, the one place where lifting day carbs I think are defensible is for your training performance. And we do have a systematic review on this from Menno Henslemans. A lot of you guys know Menno and his colleagues back in 2022. This is a 49 studies, a review of 49 studies. And what they found is very dependent on how hard your session is. And that's what I'm gonna cover at the end. I'm gonna give you a tip related to that. So, Sonny, this may be relevant to you and anyone else listening, where there is a practical reason to move your carbs around. Okay. Lisa's question is what to eat and when before and after workouts. So this is more about peri workout or pre-post-workout nutrition. My honest answer here is that timing is a much smaller variable than people want it to be. Like in our program, Eat More Lift Heavy, we don't even focus on that for a while. I mean, unless you're in our like one-on-one or our direct coaching, and then we'll give you a timing schedule early on. But it's not, it's it's a smaller variable. Get a meal with protein in it within a few hours on either side of your training. Don't train completely fasted, especially if you're doing a long,
Eating before and after you lift
Philip Pape 25:19
hard session and you have the choice to not train fasted, and focus mostly on your total protein and total the total calories. Like that's as simple as it is. So I wouldn't train fasted and I would eat some protein before and after, and I would also eat some carbs. Did I mention that part? I might have skipped that part. You want, you know, having some carbs before your workout or a few hours before your workout, or if you had a big carb dinner, that could also support into your morning workout. Now, there's one other thing that I need to mention. There is data, or there are data, on a thousand female athletes that find that the ones who practice low carb diets report disordered eating at about 80% compared to about 42% of athletes that don't have this dietary restriction. Now, again, that's an association. It's not causation. Those are young athletes. But if you are going to be low carb on multiple days a week, I would definitely keep the protein and fiber up there regardless and have enough energy available to recover from lifting because underfueling your training has other knock-on effects that could affect bone density and recovery and ultimately how well you perform and get out of the process. Okay, before we wrap up, I told you I would show you how to tell whether carbs before training is going to be more or less helpful for you. I'll get to that in a second. But before I do, this whole episode exists because you guys asked me questions, Sonny, Lisa, and others over the years. And I want more of your questions. These are some of my favorite episodes to make. So if you have something you're stuck on, training, nutrition, fat loss, reconp, doesn't matter how small it seems or if you've heard the answer before, go to witsandweig.com slash question and send it to me. Witsandweights.com slash question. I'm going to give you a direct reply either way, whether I use it on the show. You get to choose whether you want a shout out in when you submit the question. So go to witsandweights.com slash question. All right. Here's how to tell whether eating carbs before you train is going to help you with your performance. So this really goes to Sonny's question, Lisa's question as well. What a lot of people are curious about, it actually depends on how much work you're going to do in the session. And the way to determine that is the number of hard sets for each muscle group. This is pretty cool. There's that systematic review from Henselman's that I mentioned that looked at carbon resistance training performance across 49 studies. They found that if you're training in a fed state, meaning that you've eaten at some point that day before you train, carbohydrate intake itself is unlikely to affect
Bonus: hard sets and carbs before training
Philip Pape 27:54
your strength performance in sessions that are up to about 10 sets per muscle group. The actual benefit showed up above 10 sets, or when the comparison group was training fully fasted. So if you look at the number of sets in your program, if you're doing, let's say, six or eight sets for a muscle group, which is honestly what most people are doing, then restructuring your day around pre-workout carbs, you may not need to do it. And even some of my thinking has changed on this over the years. Now, I personally have a banana before I work out. I just like to have a little extra food, a little extra carb, a little extra energy. It makes feel good. But I train in the morning too, right? So take it with a grain of salt at the end of the day, experiment and see what works for you. Until next time, keep using your wits, lifting those weights. And remember, carb timing is a schedule, it's a preference, it's about your lifestyle. It is not a physiological problem. I'm Philip Hape, and I'll talk to you next time here on the Wits and Weights podcast.
