Why muscle growth changes and how to turn the odds in your favor

Building muscle isn’t a one-size-fits-all process — it’s more like a puzzle where genetics, lifestyle, and strategy play a role. For some, progress comes quickly, while others may feel like they’re spinning their wheels despite the hard work. The truth is, understanding the factors that influence muscle growth—like your body type, diet, and exercise routine—can make all the difference. By tailoring your approach to your unique physiology and goals, you can turn frustration into results and maximize every rep along the way.

We talked to the experts and dug into the science to find out why some people gain muscle faster than others. We’ll also show you how to change your routine to unlock your full muscle-building potential. Read on to learn the factors that affect your results and how you can turn them to your advantage.

Genetics and hormones play a big role

Genetics play an important role in determining your body’s ability (and limits) to build muscle, in part by influencing your hormonal and muscle makeup. But they are not the end all.

Hormones

Anabolic hormones — consist growth hormone, estrogen, insulin and testosterone — is key to building muscle. Contrary to popular belief, estrogen and testosterone are essential for muscle structure and function. Testosterone is responsible for muscle growth estrogen increases muscle mass and strengthit also increases the collagen of connective tissues such as your bones, ligaments and tendons. Women typically produce more estrogen and less testosterone than men, so men often have an easier time with visible muscle growth. (The the same seems true (for transgender people receiving hormone replacement therapy.)

“Testosterone is an anabolic hormone and is 10 times higher in men, which can benefit muscle growth goals,” explains Ryan Turner, registered dietitian, certified sports dietitian, and founder of Food is Fuel NYC. Testosterone promotes the release of growth hormonesstimulates tissue growth and binds to nuclear receptors on DNA that cause protein synthesis (or muscle growth).

As both men and women age, declines in both testosterone and estrogen hormones can result in muscle breakdown, Turner notes. Other aspects that can reduce your muscles are fluctuating hormones such as adrenaline, cortisol and glucagon that inhibit their growth. That’s why it’s important to monitor your daily stress, sleep, and diet because they affect those hormones, which in turn affect your ability to progress.

Muscle fibers

Another thing that can affect how well you put on muscle is fast and slow twitch muscle fibers. Skeletal muscles are made up of both of these fibers, which serve different purposes and determine your potential athletic ability. Fast-twitch muscle fibers are large and produce quick bursts of energy that are good for exercises like sprinting, jumping, powerlifting, and strength training. Slow-twitch muscle fibers, on the other hand, are smaller and are designed to help sustain long-term cardio exercises such as long-distance running, swimming, cycling, and any type of endurance exercise.

We all have fast-twitch and slow-twitch muscle fibers, but genetically, some people may have more fibers than others. Fast twitch fibers are what you need for big muscle growth.

“Different muscle fiber characteristics, Type I and II, slow and fast twitch, respectively, can both increase in size, but the latter may have greater growth potential,” explains Turner.

As a result of research, it was found that two genes It is known as the ACTN3 gene and the ACE geneit greatly affects which muscle fibers we have more of. The ACTN3 gene helps make a protein found in fast-twitch muscle fibers, for example, a genotype known as 577XX can occur in both genes, decreasing fast-twitch muscle fibers and increasing slow-twitch fibers. On the other hand, the 577RR genotype is associated with a greater number of fast-twitch muscle fibers.

Tendon length can also determine how big your muscles are. Tendons vary from person to person, but this has been found to be the case shorter tendons allow you to gain bigger musclesand long tendons make it difficult.

Again, it’s not all about how you were born. “There is an upper limit to muscle fiber size; but remember that without proper and consistent training, the muscle’s true potential will not be realized,” warns Turner. So just because your genetics tell you you can build muscle more easily, nothing will show for it if you don’t put in the work.

what are you eating

When talking about muscle mass, it is impossible to ignore nutrition. How you eat can make a big difference in how well your body puts on and maintains muscle. “Muscle is a very expensive tissue to maintain,” explains Tami Smith, a certified personal trainer and owner and CEO of Fit Healthy Momma. She says you have to be intentional about not only wearing it, but keeping it.

Eating enough calories and protein helps muscle recovery and growth after training. Muscle is made of protein and it is important to eat enough protein after strength training it limits the breakdown of muscle protein and promotes muscle synthesis (growth of new muscles). Turner says that individuals who exercise vigorously require more protein than their non-exercising counterparts. Older adults will generally require more, but even more so if they are strength training. Similarly, if you want to build muscle, you need to add more calories to your diet.

“Well-trained people who consume an extra 500 to 1,000 calories a day and those new to strength training who eat up to an extra 2,000 calories a day can show positive changes in muscle mass,” says Turner. “In my daily work with clients, in many cases 15-18 calories per pound has supported the client’s hypertrophy goals.” (Muscle hypertrophy refers to the growth of your muscles through exercise.)

More details: The best protein powders for your muscle gains in 2022

Of the 20 amino acids in protein, leucine is most important for promoting muscle growth — and the body cannot produce it. “Three to four grams of leucine (or 6 to 8 ounces of animal protein) can promote maximal protein synthesis,” explains Turner. If you’re a vegetarian, you’ll need to strategically prepare your meals ahead of time to achieve this, as plant-based proteins can only provide 25-60% of the recommended amount of leucine.

Some women who struggle to build muscle may be sabotaging their potential without even realizing it. “Many women fall into the diet mindset of always wanting to be smaller and weigh less on the scale, which is not conducive to building muscle,” explains Smith. She says many women dread seeing the scale go up a bit because by adding muscle, you’ll add weight. “I have a lot of clients now who weigh more but look completely different with more muscle on their bodies,” says Smith. If you allow yourself to gain that weight to build muscle, you can change the way your body looks and feels, and the number on the scale will become irrelevant.

Turner says simple nutrition strategies like meal planning, meal charts, budgeting and supplements can be implemented to overcome the challenges of figuring out your food intake. If you’re not sure where to start, it’s a good idea to consult with a sports nutritionist who can guide you on the right path for your goals.

More details: 7 Best Creatine Supplements to Increase Strength

Training strength (and rest)

After examining your nutrition and understanding how your genetics affect muscle growth, strength training is another key player.

There are two types of what is known as muscle hypertrophy myofibrillar hypertrophy and sarcoplasmic hypertrophy. Myofibrillar hypertrophy focuses on building strength, while sarcoplasmic hypertrophy increases the volume of sarcoplasmic fluid within the muscle, making it appear larger (think of the “pump” you get after an arm workout).

Depending on your goals, your training will affect whether you get stronger or have more defined muscles. Lifting lighter weights for higher reps (six to 15 reps) will give you a defined look, but you’ll often lack strength—bodybuilders use this method. To gain strength and maximize your muscle growth, you’ll need to lift heavier weights for fewer repetitions (six or fewer repetitions) and longer rest periods. Powerlifters use this method.

Either way, you need to keep challenging yourself to see continued growth over time. “It’s key to use a program that does some kind of progressive overload to continue to challenge your muscles and grow,” says Smith. This means focusing less on cardio, HIIT and circuit training and more on heavy lifting.

Also, make sure you get one a proper night’s sleep (at least 7-9 hours) helps optimize recovery after heavy exercise. While you’re resting, your body gets to work repairing muscles and regulating your hormones, which, as you already know, play a big role in building muscle. Lack of sleep not only affects your ability to perform well, but also inhibits your growth hormones.

There are many benefits of strength training besides building muscle, for example, increasing your metabolic rate, improving your lean body mass which promotes blood sugar control, reducing the risk of injury, improving mental health, strengthening bone health, and more. Aiming to strength train two to three times a week is a good rule of thumb, but if you want more guidance, consult with a personal trainer who can create a personalized program to help you reach your goals.

So what is food?

The ability to build muscle varies from person to person. However, it’s important to understand the big picture because it doesn’t start and end with your genetics. You may have the genetic profile of an Olympic athlete, but if you don’t put in the work, you’ll never know your true potential. Likewise, if you struggle to easily grow a certain muscle group, that doesn’t mean you can’t achieve it with a little extra work.

If stronger or bigger muscles are an important goal for you, watching your daily caloric intake, meeting your protein goals, and following a targeted strength training program will help increase your chances.