Illustration of a skinny guy failing to build muscle even though he's working out, getting him classified as a non-responder.

Are You a Non-Responder to Weight Training?

There’s no doubt that genetics play a role in building muscle. In fact, especially when looking at outliers, genetics can have an enormous impact. If two people do the same workout routine and eat the same bulking diet, one of those people might gain twice as much muscle.

What’s more contentious is the claim that some people can’t build muscle at all. And there’s some truth to that idea. When most people start lifting weights, they build muscle. But not everyone. And these people who don’t gain muscle have been referred to as “non-responders” or “low-responders” in the research.

So what’s going on here? Weight training is supposed to cause us to adapt by gaining muscle size and strength. Why do some people fail to adapt?

Illustration of a skinny guy failing to build muscle after lifting weights, getting him classified as a non-responder.

What’s a Non-Responder?

A non-responder (or low-responder) is someone who doesn’t gain much muscle after following a workout routine for a given amount of time. Maybe after lifting weights for ten weeks, the average person gains five pounds of lean mass, but one guy loses a pound. He’s a non-responder.

Are Non-Responders Real?

Non-responders and low-responders are real scientific terms. Researchers really do classify participants that way. But it’s not a comment on someone’s muscle-building genetics, it’s just a way of sorting the results of a particular study.

For example, in a 2021 study by Islam et al, the researchers put fourteen men through a four-week workout routine. At the end of those four weeks, the researchers measured the participants’ muscle growth and sorted them into low-responders, medium-responders, and high-responders.

Illustration of a skinny guy doing cardio.

After that, the researchers waited three months, then restarted the experiment. They ran the participants through the exact same workout program, measuring their muscle growth a second time. Again, they sorted the participants into low-responders, medium-responders, and high-responders. But this time the groups were different. Many of the low-responders became high-responders (and vice versa). So being a low-responder isn’t something that you are. It’s not a genetic trait. It just describes your results from a particular workout routine.

This makes logical sense. In the year I got married, I lost 15 pounds. So did my wife. And since we were already lean, almost all the weight we lost was muscle. We were exercising during that period, it’s just that we were stressed. We were in the middle of planning a wedding, my wife’s father passed away suddenly, and then my wife got pregnant later that year. It was a crazy year, filled with joy and sorrow and change.

But after successfully getting married, and with the pregnancy going well, the stress evaporated. We gained back those 15 pounds of muscle within a few months. Well, my wife gained more than that, obviously. She was pregnant. But she recovered all of the muscle she’d lost as well.

Now imagine what would’ve happened if we’d been participants in a muscle-building study. If that muscle-building study had been conducted during the stressful year, my wife and I would have been classified as hopeless non-responders because of our tragic loss of muscle. But if the study had taken place the following year, we would’ve (re)gained tremendous amounts of muscle. We would’ve been classified as genetically elite high-responders.

Are You A Non-Responder?

If you try to build muscle and fail, you were a non-responder. But that doesn’t mean you’ll respond the same way next time. Being a non-responder has less to do with genetics, more to do with lifestyle, circumstance, diet, stress, and sleep.

Genetics do influence how easily, quickly, and leanly we build muscle. Two guys doing everything the same might still build different amounts of muscle. This is especially true if you take someone with elite genetics and compare them against someone with atrocious genetics. In fact, even if a guy with elite genetics eats a poor diet, inconsistently follows a bad workout routine, and parties every night, he might still get better results than a guy who does everything perfectly (provided they both eat enough food to build muscle).

Graph showing the proportions of the population with good, bad, and mediocre muscle-building genetics

The thing to keep in mind, though, is that elite and atrocious genetics are rare. You probably don’t know anybody with elite genetics. You probably don’t know anyone with terrible genetics either. You probably know people with good, mediocre, and bad genetics. And within that normal range, the differences aren’t nearly as extreme. We’re talking about some guys gaining 10–20% more muscle than average (easy-gainers), other guys gaining 10–20% less muscle than average.

In most cases, genetic differences are enough to notice, but they’re rarely enough to stop someone from becoming respectably lean and strong. Most guys can (eventually, with hard work) squat at least 315 pounds, bench at least 250, and deadlift at least 405, even if their genetics are fairly bad. And if your genetics are mediocre, you can bump that up to squatting 405, benching 315, and deadlifting 495 (give or take 50 pounds).

Before and after photo showing the results of a skinny guy working out to build bigger arms and biceps.

The main takeaway here is that genetic variation has little to do with why some people are classified as non-responders. It’s normal for people with great genetics to go through periods of being non-responders. Similarly, it’s common for people with poor genetics to go through phases of gaining solid amounts of muscle.

Why Do Some People Fail to Gain Muscle?

It’s common for people to start working out, fail to get results, and then assume they’re non-responders. More often than not, it has nothing to do with their genetics, it’s just that something in their bulking routine is missing or needs to be adjusted (study).

Graph showing differences in muscle growth when eating a high-carb versus ketogenic diet.

For instance, there’s a 2018 study by Vargas et al. looking at how the ketogenic diet affects muscle growth. They found that the group eating a ketogenic diet lost 0.7 pounds of muscle while the group eating a traditional diet gained 3 pounds. Both groups were following the exact same workout routine, but because of dietary differences, some participants gained far more muscle than others. Many muscle-building studies don’t control for diet, and so many of them miss out on dietary differences causing different amounts of muscle growth.

Before and after photo showing the results of a skinny guy bulking up with the Bony to Beastly Program.

In this case, the reason the keto group lost muscle is that they weren’t able to get into a calorie surplus. They were losing weight. And if you lose weight, it’s very difficult to build muscle, especially if you’re already lean. This is a very, very common issue with us skinny guys. It’s hard for us to gain weight, and so it’s hard for us to build muscle. There’s even a special word for us: hardgainer.

How Can You Build Muscle More Reliably?

If you’re following a hypertrophy training or bodybuilding routine and you’re having trouble gaining muscle, the first thing you should do is make sure that your diet and lifestyle are on point:

  • Make sure you’re eating enough food. If you aren’t eating enough calories to gain weight, it will be hard to gain muscle. And if you’re a skinny guy who’s already fairly lean, it may actually be impossible to gain muscle without gaining weight. After all, the only way for a skinny 130-pound guy to get up to a muscular 180 pounds is to gain weight. As a rule of thumb, try to gain 0.5–1 pound on the scale each week. If that’s hard, we have a full article about how to eat more calories.
  • Make sure you’re eating enough protein. If you aren’t eating at least 0.7 grams of protein per pound bodyweight per day, your body might have trouble recovering from your workouts and building new muscle. Try bumping your protein intake up to a gram of protein per pound bodyweight per day. For more, we have a full article about how to eat a bulking diet.
  • Try to eat mostly whole foods. If you’re having trouble building muscle, another place to look is the quality of your diet. You want to be eating a diet that’s rich in whole foods: fruits, berries, veggies, legumes, nuts, olive oil, cheese, yoghurt, whole grains, berries, fish, crickets, and meat. That will give you the fibre, amino acids, vitamins, and minerals you need to support a healthy physique. For more, we have an article about the best bulking foods.
  • Make sure you’re getting enough sleep. If you aren’t getting at least 7 hours of sleep per night, you might have trouble building muscle leanly. Try getting 8 hours of good sleep each night. That should increase your rate of muscle growth while slowing your rate of fat storage. For more, we have a full article on how to sleep for muscle growth.
  • Avoid excessive drinking, drugs, smoking, and stress. It’s okay to have a beer or two a few days per week (and I certainly do), but if you’re routinely hammering yourself into the ground, it can be hard to build much muscle. The same goes with stress. Some acute stress here and there is perfectly fine, but if you’re constantly on edge, it’s not ideal for building muscle.

Once you’ve got your lifestyle handled, the next thing to look at is your workout routine.

  • Make sure that your workout routine is designed to stimulate muscle growth. Are you doing big compound exercises like the squat, bench press, deadlift, and chin-up? Are you lifting in moderate rep ranges, doing 6–20 reps on most sets? Are you lifting hard enough, bringing most sets within 0–3 reps of failure? Are you training each muscle 2–3 times per week? Are you doing at least 2–3 sets per exercise?
  • Experiment with different styles of bodybuilding and hypertrophy training. Some people respond well to heavier weights, fewer sets, and lower frequencies. Maybe they do 3 sets of 8 reps on the bench press every Monday and Friday (6 sets per week). Other people respond better to lighter weights, more sets, and higher frequencies. Maybe they do 4 sets of 12 repetitions on the bench press every Monday, Wednesday, and Friday (12 sets per week). If one style isn’t working for you, try the other.
  • Focus on getting stronger. Every workout, fight to add a bit more weight to the bar or to eke out an extra repetition. For instance, let’s say this week you do a set of 12 push-ups, a second set of 10 push-ups, and a third set of 9 push-ups. Next week, try to get an extra rep. Maybe that’s 12 reps, 11, reps, and then 9 reps. That’s progress. You won’t be able to make progress on every lift every week, but always fight for it.

If you fail to build muscle, don’t consider it a failure, consider it a lesson. The variables you were using weren’t working. What variables can you change to give yourself a better chance at succeeding?


A non-responder is someone who doesn’t gain muscle after following a workout routine for a given period of time. However, it doesn’t account for diet, lifestyle, or circumstance. When those other factors are accounted for, genetic differences do persist, but everyone can successfully build muscle.

Illustration showing the Bony to Beastly Bulking Program

If you want more muscle-building information, we have a free bulking newsletter for skinny guys. If you want a full foundational bulking program, including a 5-month full-body workout routine, diet guide, recipe book, and online coaching, check out our Bony to Beastly Bulking Program. Or, if you want a customizable intermediate bulking program, check out our Outlift Program.

Shane Duquette is the co-founder and creative lead of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's personally gained sixty pounds at 11% body fat and has nine years of experience helping over ten thousand skinny people bulk up.

Marco Walker-Ng is the co-founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell, and is a certified trainer (PTS) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. His specialty is helping people build muscle to improve their strength and general health, with clients including college, professional, and Olympic athletes.

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  1. JohnnyGo on July 22, 2021 at 3:58 pm

    Crickets, Shane? Just thought you’d slip that in there, huh. Not happening, buddy. I have chickens to eat my crickets. Then I eat my chickens’ children.

    I think something strange has happened to me. I kind of like the look of the bearded skinny dude. 🙂 After successfully bulking up on your program, I started thinking I felt too big and dreamed of slimming down to a “svelte” 180. And sure enough I’m liking it. I do miss the 15″ arms sometimes, though. But at least I know how to get them back, should the winds of change start blowing my way again.

    • Shane Duquette on July 22, 2021 at 5:15 pm

      If even chickens are eating crickets, I suppose I can’t call you too chicken to eat them. Not chicken enough, I suppose.

      Totally! Ain’t nothing wrong with not wanting to be maximally bulked. You know, I’m fond of the idea of building a bit of extra muscle, trimming down, and living maybe 10 pounds lighter than what your muscles remember. If my suspicions are correct, that’d be the easiest way to maintain a fit physique while being able to be fairly casual about it.

      And you’re right, too, that looking slim, strong, and fit can look just as sweet as looking big, strong, and fit. So no disagreement from me there.

      You know, that might make for a good article or newsletter. It might sound like we’re encouraging people to bulk up and stay at their genetic muscular potential. But that’s not what we’re about. We’re just about helping people build the body that they want. And for most people, it might be more enjoyable to stop shy of their limits.

  2. Lance on July 23, 2021 at 8:12 pm

    I do like the idea of eating whole foods and it’s what I’ve been doing for some time now. Makes sense.

    I did see crickets for sale at our local State Park. First time I ever saw them. I didn’t realize you could eat them! (Except in the Bible.)

    • Shane Duquette on July 23, 2021 at 8:31 pm

      I only started eating them after moving to Cancun. My brother-in-law offered me some mezcal with a side of crickets. Surprisingly good!

      They also make for a nice crunch in some guacamole.

  3. JeremyS on July 24, 2021 at 8:22 pm

    I wonder how much the age one starts proper training at affects their muscular and strength potential?

    I tend to think I’m a fairly poor responder to training, but not terrible. My hypertrophy has actually been pretty decent – I’m leaner at 170lb than I was at 155lb when I started lifting 2.5 years ago at the age of 34, but my strength gains have been pretty underwhelming.

    My 5-rep PRs are:
    Squat – 165lb
    Bench – 138lb
    Deadlift – 215lb
    OHP – 88lb

    I’m definitely capable of progressing my deadlift at a decent rate (maybe 5lb every 5 weeks), but progress on the other lifts has slowed to a crawl – maybe 5lb every 10 weeks and slower than that for the OHP. I’m doubtful that I’ll ever reach the strength standards mentioned in this article.

    • Shane Duquette on July 27, 2021 at 10:22 am

      Hey Jeremy, congrats on the gains, man!

      That’s a good question. I’ve wondered if the age we start lifting affects our genetic potential, too.

      I think our upbringing might play a role in our muscular potential. A child who’s raised to be quite active might develop more muscular potential. That’s just me speculating, though. I’m not sure if there’s any truth to that, and I’m not aware of any research looking into it.

      If we’re talking about someone starting lifting at 18 or 40 years old, though, then the differences aren’t very extreme. Yes, starting younger might allow someone to become slightly more muscular. But the difference is small enough that the studies I’ve seen can’t even detect the difference. 18-year-olds and 40-year-old beginners seem to build similar amounts of muscle and strength. Within 10 years, both can reach a similar place.

      As for reaching your own genetic potential, there are a few things to keep in mind.

      First, there’s a law of diminishing returns. It’s fairly easy to get 50% of the way to your potential, a bit more challenging to get 80% of the way there, and EXTREMELY difficult to get 100% of the way there. Most people choose to stop at least a bit shy of their potential, and there’s absolutely nothing wrong with that.

      Second, not everyone optimizes their lifts for strength, and that’s fine. Maybe you do deep high-bar squats. Those are amazing for gaining muscle and general strength, but you won’t be able to lift nearly as much weight as if you were doing shallower, wide-stance, low-bar squats. Or with the bench press, developing a big arch in your back might add 50 pounds to your bench without affecting your general strength or chest size.

      Third, to reach your strength potential, you need to reach your muscle size potential. To do that, you might need to gain a bunch more weight. Maybe to squat 275 for 5, you’d need to bulk up to 190 pounds. That may or may not be something you’re interested in. If you’re happy at 170, that’s cool.

      What I’d do is use those targets as very long-term goals. And maybe you never get there. But don’t let that genetic doubt creep in. Chances are, your genetics will allow you to get quite strong. And how close you get to that potential is up to your preferences and your priorities. (And just to reiterate, I’m not trying to imply that everyone ought to reach their genetic muscular potential.)

      But I do think you can gain quite a bit more muscle size and strength. The trick is to keep slowly gaining weight over time, keep trying to set new PRs every week or three, and then adjust your training routine whenever you run into a plateau. For instance, if your bench press isn’t progressing with one bench session per week, maybe you need two. Or maybe you need an extra set every workout. Or maybe you need some extra accessory lifts (such as skullcrushers).

      Another good trick is to measure and develop your strength in the hypertrophy rep range. 5-rep sets aren’t super efficient for building muscle. You might have more luck by training and testing your 10RM strength. Then, once you’re happy with your 10-rep max, you can try moving into lower rep ranges. For example, I brought my bench press 12RM up to 225 pounds before attempting to bring my 1RM to 315.

      I hope that helps!

      • JeremyS on July 27, 2021 at 5:56 pm

        Thank you for that detailed reply, Shane.

        I recognise that I’m definitely in my intermediate stage – strength and size gains aren’t as easy to come by as they used to be.

        I don’t optimise my lifts for strength – I squat high bar (and front squats) and bench with a minimal arch. My training is focused on hypertrophy – I do lift in higher rep ranges, but have always used my 5rm as the gauge for strength. Good idea, I’ll start tracking my 10rm now as well.

        I am trying to increase my body weight – last year I bulked to 180lb (at 2lb per month) but was about 20% body fat by the end. I cut back to 163lb and about 13% and have since bulked back up to 170lb and maybe 15% (I’m 6’1″ btw). Even at 2lb per month, I seem to gain a high proportion of belly fat when bulking. Getting more sleep would be nice, but with two young children and a puppy that is easier said than done!

        Despite the slow gains, I am enjoying the journey and absolutely see the 225lb bench, 315lb squat and 405lb deadlift as long term goals.

        • Shane Duquette on July 28, 2021 at 9:39 am

          I hear ya. I’ve only got one young child, and my dog is old and quiet. Even then, quality sleep is much harder to come by.

          We’ve got an article on how to gain less fat while bulking. Maybe that will help you ward off some of the belly fat.

          But overall, it sounds like you’re doing great 🙂

  4. Sparks on April 16, 2022 at 9:11 pm

    I’m a non responder – I trained for 10 years, focussed on diet and different training methods, but nothing worked. After about 5 years of research & studying and still not gaining any size or strength I ended up doing 3-4 steroid cycles. My strength increased slightly, but I didn’t notice any lean weight gain.

    During those ten years I hired 2 different bodybuilding / strength coaches and a bodybuilding nutritionist.

    I had blood work done on 3 but occasions and everything was normal.

    I’ve started training again after a few years, and nothing’s changed. I’m in my 40s now so don’t expect anything tbh.

    Can anyone offer any advice?

    • JohnnyGo on April 17, 2022 at 4:05 pm

      Were you actually gaining weight during all of this? Hormones and coaches and programming aside, if you’re not gaining weight, odds are you’re not building muscle either. You can’t put on 20 pounds of muscle without putting on 20 pounds. And odds are, you’ll put on 30-40 pounds total to get that 20 pounds of muscle.

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