Stubborn Muscles: 5 Reasons Your Muscles Aren’t Growing

Muscles aren't growing

It’s frustrating when you’re training to build muscle, putting in the work, but not seeing muscle growth. You might question whether you’re doing something wrong and what changes you need to make to jumpstart muscle growth, but first, you need to know why you’re not getting results. Here are five reasons your muscles may not be growing.

You’re Not Training for Hypertrophy

Working your muscles against resistance doesn’t always mean you’ll hypertrophy the muscles you’re working. If you lift super heavy and do a low number of reps, you’ll build strength but won’t necessarily see your muscles grow. That’s how powerlifters train and they rarely have the defined muscles that bodybuilders do, despite their superior strength. Powerlifters lift in a way that trains their nervous system to become more efficient at lifting heavy loads without big gains in muscle size. Likewise, lifting light weights and not thoroughly fatiguing the muscles can limit strength gains.

The “sweet spot” for hypertrophy gains is to lift a weight that allows you to do 8 to 10 repetitions before thoroughly fatiguing the muscles. Moderate resistance and volume optimize muscle gains. Be sure to do at least 3 sets of each exercise because total training volume matters for hypertrophy gains. For maximal muscle growth, you must fatigue the muscles you’re working. For stubborn muscles that won’t grow, it helps to take some sets to failure, although do this in moderation.

Finally, you won’t see muscle gains unless you use progressive overload. What does this mean? Boost the resistance you work your muscles against over time or increase the number of repetitions you do until the muscle fatigues. If you don’t increase the challenge, your muscles have no reason to grow and adapt. Introduce new challenges by adding advanced training techniques, like drop sets, supersets, pre-exhaust sets, or eccentric training. Give your muscles every reason to grow by introducing new challenges. That’s what your muscles need for hypertrophy gains!

Your Diet Falls Short

If you’re trying to gain weight and get leaner, you can sabotage your muscle gains by not eating enough protein and calories. This is usually more of a problem for women than men. You don’t need protein shakes or protein supplements to build muscle, but you do need a certain quantity of amino acids from protein to help rebuild the muscle fibers you break down through training. If you’re scaling back your food intake, you might not be getting enough protein or carbohydrates to support muscle gains.

Could your diet use an upgrade? If you’re consuming less than 1.5 to 2.0 grams of protein per kilogram of body weight, you may have a hard time gaining muscle and need to modify your diet. Likewise, you may need a slight calorie excess for your muscles to grow.

The best way to know whether you’re meeting your body’s macronutrient needs is to keep a food journal for a few weeks, documenting how many calories and grams of each macronutrient you’re taking in. Calories matter too. It’s hard to build muscle if you’re in a calorie deprived state.

You’re “Interfering” with Your Gains

Studies conflict whether aerobic training interferes with hypertrophy gains. However, the adaptations are different and the pathway each form of training activates differ and, in some cases, interfere with each other. Studies show that people who do both strength and aerobic training lose more body fat, but they may sacrifice some strength, power, and hypertrophy gains. In fact, research shows doing over 30 minutes of aerobic training 3 days weekly may be enough to reduce hypertrophy gains.

Your Lifestyle Falls Short

Even if you’re eating right and training appropriately, other lifestyle factors can still be the missing link. We underestimate the importance of sleep, but you need enough of it to promote muscle growth. It’s during the deepest stages of sleep that most muscle growth takes place. So, if you have poor sleep quality or simply don’t sleep enough, your gains may suffer.

In fact, lack of sleep can raise the stress hormone cortisol and that can trigger muscle and bone loss too. Likewise, ongoing mental and physical stress can produce a rise in cortisol and make it harder to gain muscle. So, it’s important that you take a holistic approach to building muscle. Don’t look at muscle building in isolation and assume that proper nutrition and training are enough.

How Much of a Role Do “Uncontrollable” Factors Play?

You might wonder whether there are things you can’t control that might contribute to poor muscle growth. How about genetics? Genetics plays a role in most things, including fitness and strength building. Some people have a mesomorphic body composition where they are naturally more muscular than endomorphs or ectomorphs. Plus, mesomorphs usually have an easier time building muscle and build it faster, especially relative to ectomorphs. Endomorphs usually build muscle easier than ectomorphs, but it’s harder to see the muscle definition since they have a higher percentage of body fat.

Most people have roughly equal quantities of slow-twitch and fast-twitch muscle fiber, but there are some outliers who have more of one than the other. If you have more fast-twitch muscle fibers, the kind optimized for strength and power, you may have an easier time building muscle. However, slow-twitch fibers can also hypertrophy, although to a lesser degree.

Age and gender play a role too. Men have more muscle than women and they have higher levels of anabolic hormones, like testosterone, that aid muscle hypertrophy. Men, on average, produce ten times more testosterone relative to women. It’s slightly harder to build muscle after the age of 50 too since levels of anabolic hormones decline in men and women with age. Plus, older people have more anabolic resistance where their muscles don’t respond as well to stimuli, like protein and training, that tell them to grow. However, you can build strength and muscle size at any age, and it’s best to focus on factors you can control though, like training, nutrition, stress management, and sleep.

The Bottom Line

Now you know some reasons your muscles may not be growing or growing fast enough. Hopefully, you can use this information to modify your diet and training. Be patient, though! You don’t develop muscle definition overnight – but over time.



  • com. “Do Cardio and Strength Training Work Against Each Other?”
  • org. “Building Muscle for Women”
  • The International Journal of Biochemistry & Cell Biology. Volume 42, Issue 9, September 2010, Pages 1371-1375.
  • The Journal of Nutrition, Volume 148, Issue 6, June 2018, Pages 900–909, https://doi.org/10.1093/jn/nxy064.
  • com. “Three Principles for Muscle Growth”


Related Articles By Cathe:

Hypertrophy Training: Does Training Too Often Interfere with Muscle Growth?

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How Quickly Your Muscles Grow in Response to Weight Training is Influenced by These 4 Factors

How Many of These Exercise Recovery Mistakes Are You Making?

What Role Does Hydration Play in Boosting Muscle Hypertrophy?

Strength Training: 5 Rules for Training to Failure


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