Philip Pape 0:01

One of the primary goals of fat loss is to preserve your hard-earned muscle while you lose weight, and traditional daily calorie restriction absolutely works for this. But there is research that shows how a simple adjustment to the timing of your calories during the week can potentially take your results to the next level. So if you are concerned about losing strength and muscle while dieting or want an edge, this episode is for you. Today, we're looking at a study that demonstrates how restructuring your weekly nutrition pattern preserved significantly more lean mass compared to continuous dieting, despite both approaches creating the identical calorie deficit. We'll go over the evidence, understand why and give you a blueprint to make it happen.

Philip Pape 0:59

Welcome to Wits and Weights, the show that helps you build a strong, healthy physique using evidence, engineering and efficiency. I'm your host, philip Hape, and today I'm excited to dig into a research-backed strategy that could give you an edge in your fat loss journey and that is strategically timed. Carbohydrate refeeds, essentially using your weekend, two days a week, to jack the carbs up so that you are eating at your maintenance calories, to potentially give you an edge when compared to having a consistent calorie intake throughout the week. Now, most of us approach dieting with that simple approach at first, which I think is a great place to start, and that is, you reduce your calories to create a deficit and you spread it out, so it's the same every day and then you do that week after week until you reach your goal, and this method absolutely works. But research suggests there could be room for optimization. And if you are in this camp of wondering how do I make this even more effective, today's episode might have you covered. Because what if restructuring the distribution of those calories throughout your week could lead to better muscle preservation and less metabolic slowdown? So today I'm looking at a fascinating study led by my good friend Dr Bill Campbell at the University of South Florida. He's been on the show several times, I had the pleasure of contributing to his research review and we go back and forth a lot on some of these topics. His study with his colleagues was called Intermittent Energy Restriction Attenuates the Loss of Fat-Free Mass in Resistance-Trained Individuals a Randomized Controlled Trial. So I know it's a mouthful. I will have the link to the open access full text of the study in the show notes. And what this research tested is whether a specific pattern of calorie distribution throughout the week could improve body composition outcomes compared to traditional daily restriction, and I kind of brushed this off because we're not brushed it off, but I'll say I brushed off the study and when I heard Bill talk about it on Karen Martell's podcast and it's from 2020, but it is worth revisiting because it still holds up and it's a very powerful potential conclusion for you to experiment with and see if it works for you.

The Science Behind Weekend Carb Refeeds

Philip Pape 3:05

Before we get into it, I do want to make sure you have access to my precision fat loss guide. This is a free guide I created a few months ago and I tweaked it a bit for today's episode to account for these refeeds. This guide complements everything we're discussing today. It walks you through the different ways you can set up your fat loss plan to make it work, based on your personal goals, lifestyle preferences and level of experience, and so it includes all of that. It also includes a whole link, a list of links to relevant episodes on fat loss, depending on where you're coming from. So if you want to download your free copy, use the link in the show notes or go to witsandweightscom slash free. Again, it's the Precision Fat Loss Guide link in the show notes, usually at the very top of the show notes. All right, let's look at the science behind this approach, and then we're going to talk about the potential mechanisms as to why it happened, why the results occurred the way they did, and then we'll talk about how to apply this practically to your own fat loss phase.

Philip Pape 4:06

So the study in 2020 was published in the Journal of Functional Morphology and Kinesiology, and this was not a study on sedentary or obese populations. It specifically examined resistance trained men and women. So it's directly relevant for those who are tuning into this podcast and focused on physique development, body composition, actually losing fat, because, remember, the premise here is to lose fat. You have to lose body weight, but you need to do it while holding on to muscle. And if this concept is new to you, I have other episodes that will go over the basics. And, again, if you get my precision fat loss guide, the links at the bottom, at the last page are will set you in the right direction.

Philip Pape 4:47

So back to the study. The researchers recruited 27 participants with an average of five years of resistance training experience, and it was a pretty simple and elegant design, I would say, in my opinion. Uh, participants were randomly assigned to one of two diet interventions, both lasting seven weeks. The first group followed a continuous energy restriction approach. That is essentially the standard method most of us use when dieting, where you have the same deficit every day, and they used a 25% calorie deficit every day of the week.

Philip Pape 5:18

The second group followed what I'm calling the weekend diet. This is the premise of today's episode, which is you reduce calories more aggressively Monday through Friday so in this case 35% and then increase calories back to maintenance on Saturday and Sunday. And again maintenance. What is that? Maintenance calories are the calories that you burn and therefore, when you are eating to those calories, you're not in a deficit or a surplus, you're just eating to maintain. And the important thing here is those additional calories on the weekend came exclusively from carbohydrates. Now, when you do this in practice we'll talk about this a bit later you don't have to be so precise with having just carbs. Some, some fat, some protein might sneak in there, but predominantly it's from carbohydrates, and there's a reason for that.

Philip Pape 6:00

And then both groups followed a supervised resistance training program four days per week. They both consumed the same high protein intake of 1.8 grams per kilogram of body weight, which is about 0.8 grams per pound of body weight, which is in the current recommendations for preserving muscle during fat loss phases. I usually give a range of 0.7 to one gram per pound. So it's right in there. And what makes this study extremely valuable is that both approaches created the same weekly deficit. So that is a controlled variable. It's very important that that is controlled.

Philip Pape 6:35

The only difference was how the calories were distributed across the week. So same training, same protein, same weekly calories, different distribution, so that you can isolate the impact of that distribution as a variable. So what did they find? Well, after seven weeks, both groups lost a similar amount of body weight and fat mass. The weekend diet group lost 3.2 kilograms of weight and 2.8 kilograms of fat kilograms of weight and 2.8 kilograms of fat. The continuous or traditional diet group lost a little more body weight, so 3.6 kilograms, but less a half kilogram less of fat at 2.3. And statistically there were no significant differences in these measures. So our first important insight from this is that restructuring your weekly calorie distribution doesn't necessarily lead to more total weight loss or even more fat loss in the short term, because the basic principle here of energy balance calories in, calories out is still gonna apply. If you create a deficit, you will lose weight. So that's important, right, we're not throwing that premise out at all by any means.

Philip Pape 7:39

But here's where the data gets interesting. When the researchers measured fat-free mass, which is all of the non-fat tissue you have, so that does include muscle, but it also includes bones, organs and water that's where the significant differences were apparent. So the weekend group lost only 0.4 kilograms of that fat-free mass. The continuous dieting group lost 1.3 kilograms, so that's more than three times as much lean tissue loss in the traditional dieting group. And critics might say, okay, this probably just reflects water retention from the higher carb intake, right? And the researchers anticipated this.

Surprising Research Results Explained

Philip Pape 8:21

They then measured dry fat-free mass, which excludes total body water. So very, very intelligent here to do that. And the results were actually more pronounced when they did that. The weekend group lost only 0.2 kilograms of dry fat-free mass Very little to no dry fat-free mass, whereas the traditional group lost 1.9 kilograms of fat-free mass. So it actually is even more pronounced when you look at only dry I should say dry fat-free mass. I mean, if you just multiply it, that's 10 times better preservation of lean tissue if you're to use a multiple. But even just in absolute terms, it's close to zero for the weekend group and it's around two kilograms for the continuous group. It's a big difference, right? Two kilograms is almost a pound of fat-free mass loss, and so that is potentially, right there, a substantial advantage if your goal is to maintain muscle and strength during fat loss, right, instead of just looking at the fat loss piece of the equation, looking at the fact that muscle was very well preserved.

Philip Pape 9:23

Now the researchers also measured resting metabolic rate RMR, right, a component of your total daily energy expenditure and they found that the weekend diet group had only half the reduction of the traditional group. Their RMR decreased by about 38 calories a day. The continuous group reduced by 78 calories per day. Now, neither number is huge in absolute terms, but we're talking only about seven weeks and I have frequently seen in my clients and myself large swings in expenditure, especially a drop during fat loss. If you could do anything to make that less, that means you could eat more food and lose the same amount of weight per week, or you can create a bigger deficit with the same amount of food, right? Either way it's an advantage and, again, both approaches are shown to be effective for fat loss. But the weekend diet strategy seems to have advantages, with preserving muscle mass and minimizing the slowdown in your metabolism, and that is huge. That is actually very huge.

Why It Works: Physiological Mechanisms

Philip Pape 10:22

So we want to understand why this is happening and if so, we have to look at the physiological mechanisms behind them. Why the heck would restructuring your weekly calories while maintaining the same deficit lead to such different body composition outcomes? The first mechanism, I think, involves the carbs and the insulin and how that impacts protein metabolism. When you consume carbs, insulin levels rise. I think many of us know that. Right, blood sugar spikes, insulin spikes, whatever you want to call it, and A lot of people think of insulin as a bad thing.

Philip Pape 10:54

They think of it as in terms of fat storage, right, and in sedentary people it can be a problem. It's often associated with prediabetes, diabetes et cetera. But when you are building muscle, when you're active, when you're lifting, it has very powerful anti-catabolic properties. I had a whole episode on this in the past about the benefit of eating carbs specifically for that purpose, which is reducing the breakdown of muscle tissue, and it's because of the insulin. So during a calorie deficit, what's happening? Well, muscle protein synthesis is happening, but also breakdown is happening, and it shifts toward net breakdown right, greater breakdown than synthesis If you can strategically bump up your insulin with these carb refeeds this weekend diet. It might create this window of reduced breakdown that is more pronounced than the increased breakdown during the week from having slightly more restrictive calories and doesn't compromise fat loss. So your net shift for the week is potentially toward a little bit less breakdown of muscle. Okay, following me on that. That's the first mechanism.

Philip Pape 12:02

The second mechanism is the impact of the continuous, prolonged energy restriction with the traditional approach on your anabolic signaling pathways. Because in extended deficit we know that it suppresses your muscle building machinery. We know this happens over time. It's why you start to lose strength, you start to lose muscle mass. It just makes it harder to maintain tissue. It's not the end of the world, right? That's why we use reasonable deficits and reasonable durations to minimize that. And you can still do that and have great results. But by periodically returning to maintenance, even for just two days a week, this weekend diet might temporarily normalize these anabolic pathways and give you a little relief from the opposite catabolic pressure that's occurring. So it gets you into I think Bill mentioned this phrase himself. He called it a neutral anabolic state as opposed to a catabolic state. Right, and that difference on just those two days again could make a difference for the week compared to the continuous group and you're taking a break.

Philip Pape 13:03

The third mechanism is the effect of muscle glycogen. We know that, of course, while you're dieting, your carbs are lower and you are depleting your muscle glycogen more than you would if you weren't restricted. That impacts your training performance. It reduces your energy available for the high intensity contractions from our lifting. And then that lower training intensity simply means less of the mechanical tension you're looking to get on your muscles, which is the primary stimulus for maintaining muscle. Long story short, fewer carbs, harder to train is hard and get as much muscle stimulus.

Philip Pape 13:37

And the weekend carb refeed effectively replenishes those stores. Right, it's like you're refilling the battery, whereas in the traditional approach it's always a little bit depleted. Well, now you're refilling it once a week and because it's on the weekend, most people train on the weekdays, right, most people, again, traditional kind of calendar approach and therefore you're really jacking up your fuel stores right before your first hard training session of the week, which sets you up maybe for more success and progress that if you're just constantly slightly depleted. And this this also brings up in my mind the idea that the weekend doesn't have to be Saturday and Sunday. You may have a shift type shift type job where you work on the weekends. It might be another two days of the week. I do think it's probably important to have the two days to be contiguous.

Philip Pape 14:23

I'm not sure the study tried to compare that, but that would be my thought. Now, the study I don't think it directly measured workout performance, but it's probably an indirect result of what was going on. It is that replenishing the glycogen on the weekend supported higher training intensity and created better conditions for muscle preservation, leading to the last component which frankly underpins everything I just said, and that's the psychological piece, the mental piece. Both study groups maintained really good adherence, over 90% completion. But if you think about the real world that we live in, knowing that you can eat more on the weekends is probably going to improve your long-term compliance and I've seen this with all types of nonlinear dieting where the variety and the ability to eat more on some days it just creates mental relief and it reduces diet fatigue and that mental relief from having the higher planned weekend refeeds makes the process more sustainable. You can stick with it long term and, granted, that doesn't speak directly to the weekly muscle preservation and metabolic slowdown, but it does allow you to stick with the diet and it's a great reason to consider this anyway reason to consider this anyway. So that's, that's, in my opinion, the main mechanisms.

Practical Application for Your Fat Loss

Philip Pape 15:44

And notice, I didn't mention leptin in there. I'll get back to that a little bit later because there's some, I'll say, myths about leptin replenishment and how effective that is, but we'll get back to that. I want to talk about now how you apply these to your fat loss approach and make it practical. So the very first thing we always have to do during fat loss is prepare for it, and I'm going to assume you've done that. That's outside the scope of today's episode, but effectively, you've started training consistently, you're tracking your food, you're eating sufficient protein and you know what your maintenance calories are.

Philip Pape 16:11

Now how do you know your maintenance calories? Well, you've been tracking your food and weight for at least two to three weeks. Now. You can do that on your own or you can do that in Macrofactor, which is my favorite app. It's the only app on the market that does this Chronometer, myfitnesspal none of those apps can actually estimate your expenditure and give you real targets each week based on that. So download Macrofactor from your app store. If you don't have it already, use my code, witsandweightweights. All one word for two weeks free and it's going to change your life.

Philip Pape 16:38

But that's what you need to start with is knowing what your maintenance calories are. Once you know that, you can say okay, what rate of loss do I want to go after? For most people, a half a percent a week is really solid, but up to 1% of your body weight per week, which is kind of the upper end for most people outside of advanced populations that I work with, which might go more aggressively, but usually that's the max. And that's because you want to balance the meaningful progress right. You don't want to just take two years for fat loss, you want to do it in a fairly decent timeframe. But you also want it to be sustainable, mentally sustainable, right? Not just with the weekend diet approach we're going to talk about, but just in general the amount of calories that you eat and keeping in mind that the weekend diet approach is going to reduce your weekday calories even further. So you might not want to go as aggressively because of it.

Philip Pape 17:29

So I'm going to use a I'll call it moderately aggressive number in here of 0.75% just to crunch some numbers for you and give you an idea of what it looks like. So let's say you weigh 180 pounds and you're saying, okay, I'm going to lose 1.35 pounds a week. And since a pound of fat contains 3,500 calories, roughly this translates to a weekly deficit. Okay, for the whole week a deficit of 4,725 calories, so a little over 4,700 calories. So instead of distributing that evenly, which would be a 675 calorie a day deficit, the weekend diet is going to concentrate that deficit into the five weekdays. So now you're going to divide that calories by five and that gives you a weekday deficit of 945 calories.

Philip Pape 18:14

So if your maintenance intake, your maintenance calories, are 2,500 a day right, that's how many calories you burn, and if you ate that you would maintain your weight you would now want to consume around 1,555 calories during the weekdays. Let's round it to 1,600, so the numbers aren't too complicated. So you would be eating 1600 calories a day Monday through Friday, but then on Saturday and Sunday you jack it up to your maintenance at 2500 calories, with the increase coming primarily from carbohydrates. So if you do some math, it comes out to like an extra 200 something grams of carbs on Saturday and Sunday, which is a decent amount of carbs, and the resulting glycogen flooding your system. And so what this does is it creates the same weekly energy deficit as if you spread it out across seven days. But now you have these structured periods of higher energy availability that, according to this study, might better preserve muscle mass and metabolic rate, and potentially to a really nice degree. So for optimal results here, you are going to have sufficient protein, which is again about 0.8 grams per pound in this case, and for our 180 pound example, that means 145 grams of protein a day. Your fat is going to be pegged at some reasonable amount, usually around 30% of your calories, and then the rest come from carbs.

Philip Pape 19:38

Now, when you go on the weekend side of the diet, right when the weekend comes around, you want to add in the extra calories from mostly carbs. But again, naturally, you might increase your fats and proteins, because a lot of the food we eat is a blend of macros, it's not just carbs. Now, granted, if you just add more rice or add more potatoes, you're going to have mostly carbohydrates, you know. Add more fruit. Those are the sources of carbs that I would generally recommend are whole food sources of carbs, but of course you can have some indulgences in there, like we discuss.

Philip Pape 20:09

When it comes to flexible dieting, and here's the cool thing about the weekend diet it aligns really well with how most people live their life. Right, most people have the. They go out on the weekends, they have the social situations, the parties, the travel. All of that happens on the weekends generally, again, unless you have a different schedule, and so these higher calorie days are perhaps more enjoyable, more practical to implement. Because of these real world lifestyle constraints and because you've planned it in, it becomes even less fatiguing and less of a strain on your ability to feel successful, right, like every week is a win because you've planned in all this food. And, by the way, let me tell you, when you do this and you get used to your weekly structure and then Friday comes along and then you get to Saturday, it might actually feel like a lot of food to bump up those carbs on Saturday and Sunday. So that's where deciding how to do it and how to adjust your timing and meal planning appropriately for the Saturday and Sunday, treating them as different than the rest of the week, is going to be really important here. So the Campbell study did measure leptin I wanted to talk about leptin real quick leptin levels and they found that they predictably decreased during the diet in both groups, which is expected, and past research has revealed something about carbs and leptin specifically that I wanted to cover today that, I think, adds another dimension to this weekend diet If you think of leptin.

Optimizing Leptin and Metabolic Adaptation

Philip Pape 21:32

Leptin is your body's satiety hormone. It signals that you have enough energy coming in. It tells your brain I've got enough energy coming in and so I'm fine, I'm full, I'm satisfied. When you're in a diet, when you're dieting with restricted calories, the leptin goes down and that's what triggers increased hunger. It also is tied to your metabolic rate. You have an adaptive response we call it metabolic adaptation which is tied to multiple hormones, including thyroid, insulin, cortisol, et cetera.

Philip Pape 22:01

But leptin's a very, very important one. It's the primary trigger for this adaptive response and that is why many of us have trouble prolonging our diets for too long, because your calories just drop, drop, drop, drop and you have to drop the calories along with them, or you just don't lose as fast when you think of carbohydrates, especially when you consume them in high amounts above your daily energy requirements. So in this case we're jacking up to maintenance which potentially is even slightly above your true maintenance at the moment. When you do that, we know that it can rapidly increase leptin on those days. And this is a temporary thing, right, it's just temporary. It doesn't permanently increase your metabolism or anything that some of the influencers try to convince you of with reverse dieting and all that. No, it's a temporary hormonal response and it might attenuate or mitigate some of the adaptive mechanisms from the dieting, from the energy restriction, even if it is just for a few days. But it gives you, yes, physiological relief, because the leptin is higher and you've got the energy flooding your system, but also mental relief from the stress of dieting.

Philip Pape 23:06

And this is what it effectively does, is it turns your weekend into a, an advantage, and that's why I like this approach. And also, you don't view you don't view going higher on the weekend, like when you go out to eat and you have the appetizer and you have the dessert as this failure, as this all or nothing thing. You're actually optimizing, planning it in, structuring it in. It's pretty cool. It's not cheating either. It's not a cheat weekend Because you're not just going hog wild with unfettered access to whatever. You are strategically bumping up your carbs and, by the way, we do this in a very micro level. When we do rapid fat loss, we'll do like four days of very severe restriction and then one day of refeed, and again, we're not cheating on those days, we're strategically bringing up the carbs. So this weekend diet recognizes that your body's not just a calorie calculator. It is a very complex adaptive system and it responds to all the inputs how much you eat, when you eat it, how you move, how you train, all of it. And so we're kind of making this work with our natural rhythms instead of fighting against them, and so it makes it super sustainable.

Key Takeaways and Implementation Tips

Philip Pape 24:13

I'm actually going to be telling, uh suggesting more of my clients consider this than I have in the past, specifically because I re-reviewed what the evidence has said and I think there is a lot of validity to this. So, to summarize, dr Campbell's research which again shout out to him for doing this work in his lab down at USF suggests that the weekend diet reducing calories more aggressively Monday through Friday, and then increasing carbs to maintenance on weekends, could give you advantages for preserving muscle and mitigating some of the metabolic slowdown. Remember, it's the same fat loss but it's more muscle retention. So, effectively, it's more fat loss, because now maybe you could go a little more aggressively and hold on to muscle and lose a little more fat, or you could simply stay where you are, eat more food, potentially have better training performance, better psychological adherence all of those things we talked about and it naturally aligns with most people's lifestyle patterns, which we're all about here. We're all about, like, making it work for your lifestyle rather than white knuckling it and pushing through.

Philip Pape 25:19

So if you've tried fat loss in the past and you had, say, more muscle loss than you wanted, or your performance dropped faster than you wanted and or even just psychologically it felt like a slog, try this out. Right, try this out. It's the weekend diet. It couldn't be simpler. If you're using macro factor, I suggest doing it this way. I suggest setting the deficit to the Monday through Friday deficit and just distributing the calories evenly, but on the weekends, just manually increase your carbs. I think that's the easiest way to manage it in the app. Alternatively, you could use the collaborative mode to adjust the macros a little bit manually, which I believe you could also make it work that way. So, whatever works for you, if you're working with me as a client, I'll tell you exactly how to do it.

Philip Pape 26:05

Anyway, last thing I'm going to leave you with is again download my free Precision Fat Loss Guide, and I'm asking you to do that because it does contain all of the possible flexible and creative approaches to fat loss that you might consider how to do them, the speed, the duration, who it's good for, who it's not good for, and they've got check boxes and Xs basically in these tables to tell you like this is probably the ideal dieting approach for you right now and then that can set you off on a chain of discovery and learning and setting up your fat loss phase for success. Just go to witsandweightscom, slash free, or just click the link in the show notes at the top to get your copy today. All right, Until next time, keep using your wits lifting those weights and remember that sometimes the smartest approach isn't doing the same thing every day, but finding the right rhythm that works for you. I'll talk to you next time here on the Wits and Weights podcast.