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Want to know if you're actually building muscle or just gaining fat during your bulk? 

Learn about the Muscle Gain Efficiency (MGE) score and how to use engineering's Bottleneck Effect to optimize your muscle-building system.

Discover how factors like training experience, frame size, and strength ratios influence your muscle-building potential, then learn to identify and fix what's limiting your gains.

Main Takeaways:

• You have a unique muscle-building potential

• Your Muscle Gain Efficiency (MGE) indicates how well you're gaining muscle vs. fat (how "efficient" you are)

• The 5 key bottlenecks that limit your muscle-building success

• Having a solid system + consistency = sustainable results

Timestamps: 

0:01 - Why we need a better way to measure muscle gains
3:05 - Introducing Muscle Gain Index (MGI) and Muscle Gain Efficiency (MGE)
7:31 - Interpreting your MGE score
9:46 - The 5 bottlenecks holding back your gains
19:13 - Using data to validate progress
21:30 - Tips to implement for your next muscle building phase

Get 14 days and your first challenge FREE in Wits & Weights Physique University (WWPU) plus the MGE calculator and a 40% off discount exclusive to podcast listeners

How Efficient Are Your Muscle Gains?

Most lifters track their weight during a bulk, but that number doesn’t tell the full story. Sure, the scale is moving, but how much of that weight is actual muscle, and how much is just fat?

That’s where Muscle Gain Efficiency (MGE) Score comes in—a system I developed using an engineering concept called the bottleneck effect to measure how efficiently you’re converting your calories into muscle. In this article, we’ll break down how to calculate your true muscle-building efficiency, what factors influence your potential, and how to fix the biggest roadblocks holding back your gains.

Your Body is a “Muscle-Building Factory”

Think of your body as a muscle-building factory. Every factory has:

• A theoretical maximum output (how much muscle it can build under ideal conditions)

• An efficiency rating (how well it actually converts inputs—like food and training—into muscle)

Your Muscle Gain Index (MGI) represents your potential for muscle growth, while your Muscle Gain Efficiency (MGE) tells you how well you’re achieving that potential.

MGE is a score from 0 to 1 that represents the ratio of muscle to total weight gained.

• 0.1–0.3: Poor efficiency (mostly fat gain, minimal muscle)

• 0.4–0.6: Moderate efficiency (balanced muscle and fat gain)

• 0.7+: High efficiency (maximizing muscle gain while minimizing fat)

• >1.0: Recomp territory—building muscle while losing fat

The higher your score, the more efficiently you’re packing on lean mass.

What’s Bottlenecking Your Gains?

If your MGE score is lower than expected, something is slowing down your muscle-building process. Here are the five bottlenecks that could be limiting your gains:

1. Training Bottleneck (Weakness or Poor Program)

• Not following a structured progressive overload program

• Avoiding compound lifts like squats, deadlifts, and presses

• Lifting too light or not training close enough to failure

Fix: Use strength-based programming, track your strength-to-bodyweight ratio, and progressively overload every lift.

2. Nutrition Bottleneck (Inconsistent Eating or Poor Macros)

• Inconsistent calorie intake (some days too high, some too low)

• Not eating enough protein (aim for 0.7–1g per pound of body weight)

• Gaining too fast or too slow, affecting muscle-to-fat ratio

Fix: Plan meals ahead, stay consistent with protein, and aim for controlled weight gain (0.5–1 lb/week).

3. Recovery Bottleneck (Sleep & Stress Issues)

• Poor sleep quality or low energy levels

• Constant fatigue or the need for frequent deloads

• Chronic high stress raising cortisol and slowing muscle growth

Fix: Improve sleep quality, manage stress, and prioritize rest days. If you constantly need deloads, adjust training volume.

4. Body Composition Bottleneck (Starting Too High or Low in Body Fat)

• Too lean: Your body resists gaining muscle to preserve energy

• Too high in body fat: Poor nutrient partitioning, leading to more fat gain

• Hormonal imbalances affecting metabolism and muscle protein synthesis

Fix: Optimize body fat levels before bulking, use phased nutrition strategies, and strength train year-round to maintain a high metabolic rate.

5. System Integration Bottleneck (Lack of Strategy or Tracking)

• No long-term plan for muscle growth

• Not tracking key metrics like weight trends, strength progress, or macros

• Following a randomized approach instead of a structured one

Fix: Use a tracking system, periodize your nutrition and training, and follow a step-by-step approach to muscle gain.

How to Use MGE to Optimize Your Bulk

To maximize your muscle-building efficiency:

1. Track your weight and body fat over the course of your bulk

2. Calculate your MGE score (inside my Physique University calculator)

3. Identify your biggest bottleneck (training, nutrition, recovery, body composition, or strategy)

4. Fix one thing at a time and reassess every 4–6 weeks

The Big Takeaway

Muscle gain isn’t just about eating more—it’s about gaining efficiently. Your MGE score helps you measure progress beyond the scale, ensuring you’re actually building muscle instead of just getting fluffy.

If you’ve ever felt like your gains aren’t what they should be, this is your tool to fix it.

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Transcript

Philip Pape: 0:01

Let's say you've been building muscle, tracking your weight, watching it go up steadily during your bulk and the number on the scale is going up, but it doesn't tell you how much of that gain is actually muscle. What if there was a way to know exactly how efficient your muscle building efforts are? Using an engineering concept called the bottleneck effect, I've created a system that measures your true muscle building potential and efficiency, and today I am introducing how the MGE score muscle gain efficiency can tell you if you're mostly building muscle or just gaining fat. You'll learn the factors that determine your baseline muscle mass potential, how to calculate your efficiency score and, most importantly, how to identify and fix whatever's holding back your gains. Welcome to Wits and Weights, the show that helps you build a strong, healthy physique using evidence, engineering and efficiency.

Philip Pape: 1:04

I'm your host, philip Pape, and today I'm introducing a revolutionary way to measure your muscle building success. I want you to think of your body as a muscle building factory. Engineers know that every factory has a theoretical maximum output and actual production efficiency. Your body's no different. There's your potential for muscle growth, which I call the muscle gain index, and then there's how efficiently you're reaching that potential your muscle gain efficiency, both of which are new scores that I've created. They are part of a spreadsheet, a tool where you can plug in some numbers between the beginning and end of your bulk and see how efficient you were at gaining muscle. Now, before we dive into the score and how to use it, if you want to actually access that complete calculator, along with some other evidence-based tracking tools like a body composition tracker and a biofeedback tracker, they're only available in Wits and Weights Physique University. I saved my most juicy choice calculators for that group and all you have to do is join, and I don't know what you're waiting for. It is super affordable and it is extremely valuable. Go to whatsoeightscom slash physique or click the link in my show notes to learn more about the Physique University, where you can take your tracking and results to the next level. This is only for people who are lifters, who are frustrated that they haven't quite gotten the fat loss or muscle gain output that they want, and we help you dial it in. We onboard you, we take you through a step-by-step method and process based on evidence and we tell you exactly how to measure and calculate those things so that you have utmost confidence and no more ambiguity or questions about what your metabolism is doing, how to train, how to eat, and then you can get that result with tons of support and accountability. So if you want to join Wits and Weights Physique University and get access to the exact calculator I'm talking about today, check out the link in the show notes or go to witsandweightcom slash physique.

Philip Pape: 3:05

Now, stick around anyway, because I am going to explain generally how this works and you'll understand what matters. So, whether you have the calculator or not, so that you know how to go into your next muscle building phase and do it efficiently. So I'm going to start by understanding our theoretical maximum output. Right, if we think of the factory analogy here, because this is an engineering episode, what we want to do is avoid bottlenecks. We want to understand the maximum, but then we also want to avoid bottlenecks.

Philip Pape: 3:36

So the theoretical maximum output for you is your muscle gain index, mgi. Muscle gain index, mgi. This actually tells us how much of your lean body mass is likely skeletal muscle mass, based on key factors that influence muscle building potential. Okay, listen to that again. When you gain weight to build muscle, you're going to gain some body fat and you're going to gain some lean mass. What I do with the muscle gain index is tease out how much of that lean mass is likely skeletal muscle mass, so actual muscle mass, because not all of it is muscle. Some of it is bone, fluid, organ, other tissue, and we need to understand how much is muscle.

Philip Pape: 4:16

And the factors that affect your muscle are like, let's say, the specifications of your factory's machines, right? So there's a list of these. First there's whether you're male or female, because that's going to affect your baseline muscle mass potential, not, I repeat, not the rate at which you gain muscle. Ladies, men, it's exactly the same, no matter your sex, no matter your age. What's different is the baseline potential, because men start with a higher baseline, given that they have more muscle mass, but it's only about 2%. Believe it or not, it's only about 2%, so it's actually quite negligible.

Philip Pape: 4:50

Age is the next factor that's going to impact your muscle building capacity, because the older we get and by older I mean over 50, over 60, your muscle building capacity declines just a tad, just a tiny, tiny bit. But guess what? It's always there. You always can build muscle to the day you die, all the way through into your 90s, we've seen, but it does have a small impact less you're stronger and then you might. So there's kind of this counteracting forces going on which leads me to your strength to body weight ratio, and we can measure that through your squat or we can measure it through your deadlift, for example, and that's your current performance. That is also going to affect your muscle gain efficiency. Then we have your frame size, and that can be measured by your wrist. That can tell us do you have a small, medium or large frame? And that also determines how much of that percentage of lean mass is skeletal mass as opposed to maybe just bone right or representing something that is not muscle mass. And then, finally, your current body fat percentage, which influences hormones. It also influences your muscle building efficiency, your muscle building efficiency.

Philip Pape: 6:04

So the muscle gain index that I came up with is a formula that accounts for all of these things. So in the calculator I created, you basically plug those in and it gives you an estimated skeletal muscle mass out of your lean mass and it pushes it up or down depending on all of these factors. So a young male with years of training experience and strong lifts might have very high potential, while someone starting out would have room to grow but the benefit of newbie gains. So it's kind of balanced between all of these. So that's kind of the potential of your body, of your factory, and now we have to measure how efficiently that it's running. And this is your MGE, your muscle gain efficiency. That number tells us how much of your weight change is actually muscle and how efficient it is. So it's roughly a number between zero and one, the way that I came up with it, and this accounts for the changes in your muscle mass, the changes in your total body weight, and whether you're bulking, cutting or recomping as well, because I don't want to ding you if you are cutting and of course you've retained or gained a little muscle mass, even though it's small. The fact that you're cutting means you might have been pretty efficient at cutting, gaining muscle, because you did better than the average, if that makes sense. So I'll give you some real world example, right, or examples for this score, this muscle gain efficiency A score near the bottom, near about 0.1, remember this goes around zero to one.

Philip Pape: 7:31

There are possibilities of going negative and possibilities of going one, but those are very extreme cases. So a score near 0.1 just means a very poor bulk. It means you gained almost all fat. A score in the middle, around 0.5, is hey, this is a pretty good bulk, it's pretty decent bulk. You've balanced your muscle and fat gain. A score above 0.6 shows high efficiency, right, you're actually gaining a lot more muscle than fat. And then, if you're like re-comping, you could see scores over one, which is like the holy grail of gaining muscle while losing fat.

Philip Pape: 8:04

But the asterisk on that, folks, when you think about that, is the quantity of muscle might not be that much. In other words, it's, it's very efficient, but because you're not actually gaining weight, you have to multiply that efficiency by how much weight you're gaining, which is small. It's going to stretch out the duration by months or years to actually gain the same amount of muscle as somebody who's at like a 0.6, but gaining weight faster, if that makes sense, right. So I know it sounds a little bit confusing. If you have the spreadsheet, it makes total sense. It actually calculates it for you and then it says oh, here's your number and here's how efficient it is, and here's what you might do differently next time. Um, but, and the other thing I want to clarify is a 0.5 doesn't mean it's like 50% lean mass, 50% fat. However, it does almost mean you've gained 50% muscle to fat. You get what I'm saying. So it's a little bit of a different way to look at the data that you can't just easily calculate from knowing your body fat.

Philip Pape: 9:03

All right, so when the score is lower than expected, something is bottlenecking your gains, and that is really the point of this episode is not to say, hey, you know, here's a calculator, here's a formula. I'm not even going through the math and, honestly, even if you don't have the spreadsheet, you can still do the right things to have the best success. I just know some people love to have that feedback and that data to really dive in and level up to the next level, and that's what we help people do in our coaching program and in the Physique University. So if that's you listening, you're like, yeah, I need to get to that level. Definitely reach out and join, definitely reach out and join. But if your score is lower, uh, there are five potential bottlenecks.

Philip Pape: 9:46

All right, the first bottleneck is the training bottleneck, and that is where you basically you're weak. You just don't have a high squat to body weight ratio. Something has stalled out, right, you haven't either that or you're a newbie. And again, I want to kind of separate training age, because if you are fairly new to this, you're going to gain muscle fairly quickly, but you still have to be on the right program. You still have to have the right progression, the right amount of volume, incorporating the big systemic, compound movements, proper intensity. All of that is basically going to fix this issue. So if weakness, if a lack of strength, is a thing preventing you from gaining muscle, you are always going to be stalled and you are always going to gain more fat than muscle in the future when you try to gain weight and this could have been your problem most of your life. If you're not training properly, if you just hit the gym randomly, if you just use the machines without regard for progress over time, that's what's going to happen.

Philip Pape: 10:38

Somebody in our Facebook group just posted hey, I want to go into a fat loss phase. I'm not sure how to train and, by the way, for the last two months, even though I'm not in fat loss, I haven't made any progress on my lifts and I said whoa, whoa, whoa, whoa, whoa. Okay, you're not even ready for fat loss. My man, like we. We got to fix that before you do fat loss, before you do a gaining phase, whatever. So that's the training bottleneck that's. That's a big one for a lot of people. And again, in you know, in our coaching, we take you through the steps to find out where's the issue for you. Is it your form? Is it your progression? Are you not understanding how to, like, use micro plates or something to go up at the right level? Um, are you even using the right program, et cetera, right?

Philip Pape: 11:20

The second bottleneck is nutrition. So this is where you have either your weight gain is too rapid or you don't have enough protein, or you're very inconsistent with your eating. You know, inconsistency is the big one here and the fix, of course, is consistency with your protein at that 0.7 to 1 gram per pound, a controlled rate of gain when you're bulking or when you're cutting, of course. But one of the problems people have is they bulk in a very seesaw roller coaster way where they'll eat a lot more food on certain days than other and on the weekly average they're kind of bulking and on certain days they're way overconsking and on certain days they're way over consuming and certain days they're actually under consuming. It just creates chaos to their body. Where you're not efficiently gaining, you're not using meal planning. That's. The fix is to use meal planning, meal prep, always plan ahead and know what you're gonna eat you know, not down to like every single ingredient, but it could just be the general foods or types of foods and making sure to plan ahead.

Philip Pape: 12:20

The third bottleneck is recovery. So poor sleep quality, constant fatigue, no rest days. You know, when I hear someone say I have to have deloads constantly, that's a big red flag. You shouldn't need deloads very much at all, depending on the program, or ever if it's built into the program. And this could definitely be a different issue related to sleep or stress, or the wrong kind of lift for you, or pushing too hard and trying to overreach or you're not taking enough rest, and so obviously the fix here is that consistent sleep, bedtime, wake time, consistent amount of sleep that you need. Maybe it's seven, maybe it's eight hours, you know, maybe it's six and a half. Having deloads, yes, if you need them. I talked about this in episode I think it was 282, about the only strength standard you need. We talked about progressive overload and I briefly discussed deloads in there about how, ideally, if you structure your program the right way, you hardly ever need them, and then, of course, managing your stress, whether that's managing your perceived stress, having stress coping mechanisms, tracking the data associated with stress, like HRV, and focusing on sleep to improve your stress, and so on. Right, so that's the recovery bottleneck that's going to hold you back from building meaningful muscle. Yes, even when you're gaining and eating a lot of food, improper recovery could happen, because now you're able to train much harder, but you're also able to push past the limit much more easily. Much harder, but you're also able to push past the limit much more easily.

Philip Pape: 13:39

Bottleneck number four out of our five bottlenecks is the body composition bottleneck, where, if your body fat is too high or too low, or you have poor nutrient partitioning, or you have hormonal issues, things like that, there could be a lot of different causes depending on the person, and so that's why I lumped it kind of into its own category. It could it could have to be with the fact that you are not optimizing the body fat range to be in for you. Like some people say well, I have to get down to X percent body fat and I want to live there. Well, for you that might be way too shredded and unhealthy. For another person, it might be perfectly normal. So we have to have realistic expectations.

Philip Pape: 14:18

Also, phasing, periodizing your approach I mean that is the bread and butter of what we do in our coaching is we develop periods and phases for you. I mean, when I give you your nutrition plan when you join Physique University, one of the main features in there is explaining what to do over each various range of weeks, like weeks one through four. You're going to do this, weeks five through 12, you're going to do this and we phase the approach to kind of ease you in properly. So you're doing the right things and developing the right habits and it also works really well with your body, your hormones, your body composition. And the last thing as part of this bottleneck is addressing hormone health. And I do love to address hormone health with lifestyle, which means strength training, lots of walking, managing stress and eating plenty of food, first to see what gets normalized, before you then say, well, okay, I still have certain hormones that are far out of whack. I need HRT or some sort of treatment. So that's the body composition bottleneck.

Philip Pape: 15:11

And, by the way, ladies who are in peri and post-menopause, body composition is going to get worse if you're not lifting weights and it's the main reason your metabolism drops during that time of life, because your muscle mass drops, your fat goes up, even if you maintain the same scale weight, and then it does a number with your hormones and everything just cascades. You know, thyroid, cortisol, insulin it all cascades and a lot of times all you've got to do is take off some of that stress and start lifting weights. Really, that's sometimes what the main fix is. The last bottleneck is the system integration bottleneck. This is about your overall system.

Philip Pape: 15:48

We talk about system engineering and physique engineering and that is your goals, your approach, your consistency. You know if your goal is mismatched to what you're doing, or you're trying to go too quickly for the quick fix, or the approach you're trying to take doesn't quite jive with the evidence or your body, or you're not consistent, those are all gonna be bottlenecks to gaining muscle. And the fix is gonna be having all of these aligned with you, with your lifestyle, with your body, with your needs, with your preferences, focusing on one phase at a time, one goal at a time and, of course, tracking and measuring everything that matters. Tracking and measuring everything that matters and I could have put this at the top of the list everyone because 90% of the time, when someone reaches out, they're new to the community, they're new to the podcast and they say I'm struggling with X, maybe X is binging on the weekends, maybe it's, you know, with their lifting. I say, are you tracking? And they're like, oh no, I'm not tracking. What should I track? Right, if they're open to it. I hope you're open to it and then I'll give some free resources on how to do that.

Philip Pape: 16:51

One of the best resources is my Nutrition 101 guide. If you're looking for something free, go. If you're looking for something free, go to whatsoeightscom, slash free and you can find that it actually tells you how to set up your calories and macros, the correct way dynamically to work with your body, and then how to do it for the different phases. So all of these things, these system things I know it sounds complicated if you're new to this or if this is the first episode you've ever heard of my podcast, but it really does put you in a situation where it's sustainable rather than a quick fix, where it's part of your life, where you don't have to cut out all carbs or all plants or whatever extreme diet and you can just focus, actually have the confidence, actually make the progress. Everything is aligned and part of why you're able to be successful is because you know what the heck is going on and you know what's going in your mouth and you know what your squat was two weeks ago, right, and you're tracking and measuring the right things, all right.

Philip Pape: 17:43

So that's kind of the meat of this episode was what the bottlenecks might be that would prevent your muscle gain efficiency from being higher than it could be. And for most people that means if it's like, as in the 0.2, 0.3 range, we can get it up into the 0.5 to 0.7 range and you're golden, like getting it to 0.8, 0.9,. That's usually not realistic for most people, it's just it's kind of the extremes of the range. So, to use this score, if you have our calculator, if you're in Physique University and you actually have the calculator, the way it would work is you would enter your numbers from before and after, right, or you can do it in the middle of a bulk to see how efficient it is going, because a bulk is usually six, nine, 12 months anyway. So if you're three months in, you can calculate how efficient you are. So you're going to calculate your muscle gain index, that's, your skeletal muscle mass that you're possibly gaining. That's your potential. Then you're going to see how efficient your muscle gain efficiency is and then you can use that to reverse, engineer what your bottleneck is and fix one thing at a time and reassess every four to six weeks and you're golden. That's how we do. That's how we do it. It's continuous improvement and feedback.

Philip Pape: 18:49

So what's really fascinating? When it comes down to cause, I'm so nerdy and data centric. I love my Excel spreadsheets and, by the way, this is an Excel spreadsheet and even if you're not in quote unquote into that stuff, having these different angles of data can reveal patterns that are just not visible with the stuff everybody uses. Like they're not going to be visible. If you just take your scale weight right.

Philip Pape: 19:13

If I have a client who's frustrated because their gains are quote unquote slow but their MGE score shows that they're actually building very efficiently, let's say at a 0.6, well above average. And we look at all the data, how it correlates, and we're like, actually you're doing a fantastic job. It's just you don't quite have the patience. Yet this is the first time you've gone through it. Your expectations are skewed by social media. But understanding your true efficiency, then it. Then it changes their perspective and it changes their motivation. In fact, I just had a client. We just ended our six month um contract together, um, you know, and we're parting ways amicably, like I do with many clients who they learn what they need to learn. They're they're good to go and they they're, you know, happy to tell others about me and move on, and that's what I love to see.

Philip Pape: 20:00

You fire me as a coach and she, along the way, she always had a little bit of frustration where it seemed like things weren't quite moving. And at the end of it all, we crunched the numbers and we said, wow, you dropped 9% body fat and, by the way, she only weighed like 120 pounds when we started. So she was already pretty light and lean like 120 pounds when we started. So she was already pretty light and lean. She's shorter, she's a leaner frame and we had to take it very reasonably during the fat loss, so she wasn't down at 800 calories and at the end of the day over you know a three, four month fat loss phase, pretty typical she lost 9% of her body fat and, what's interesting, it wasn't just fat loss. She actually gained, I think, three and a half or four pounds of muscle as part of it. So her scale weight didn't drop as much as she expected when we started, but she was actually happier with the results because she was leaner than when we started, like quite a bit, and so all of this stuff is super fascinating.

Philip Pape: 20:54

It's why I love frameworks and the engineering side of it all. It strips away the emotion. It gives us concrete data to work with. Your body is so sophisticated it's the most sophisticated factory that you'll ever operate and it deserves this level of analysis, at least initially, so that you can know what the heck is going on if you're struggling right. It's not necessarily a long-term thing, although many of us get the bug and we always want to have our numbers and things like that. It's really about becoming more in tune with yourself, whether it's through numbers or through journaling or through whatever method of tracking makes sense for you, but it's doing something to get that feedback All right.

Philip Pape: 21:30

So, as we wrap up, remember you have a muscle building potential and there's a certain efficiency you can go at to reach that potential, and bottlenecks are what limit your efficiency.

Philip Pape: 21:40

So, understanding the five bottlenecks, you can then focus on one of them at a time and slowly crack the armor holding you back from building as much muscle as you want to build. If you want to calculate your own MGA score, if you love data, like me, if you're nerdy about this, if you really want to level it up, take it to the next level. This, if you really want to level it up, take it to the next level. If you want to access our complete suite of tracking tools and, more importantly, the accountability support strategy to actually get the result you want for fat loss and building muscle, join Wits and Weights Physique University today. Head to witsandweightscom, slash physique or click the link in the show notes to learn more about WWPU and start optimizing your gains. Until next time, keep using your wits lifting those weights and remember, in the factory of your physique, removing those bottlenecks will help your gains soar. I'll talk to you next time here on the Wits and Weights Podcast.