It doesn’t take an expert to understand the basic idea behind building muscle. Lift weights, eat enough protein and, eventually, you’ll probably get stronger. That may be an oversimplification, but it’s not entirely off from what actually happens.

Take even a passing interest in weightlifting, though, and your phone will eventually catch on. Before long, you may find yourself scrolling through advice about how much protein to eat, which supplements to take and whether one style of training is better than another. Some people might recommend lifting until your muscles physically cannot complete another repetition — a practice called “training to failure.” Others might even tout the benefits of weighing your food or cycling between periods of eating more to gain muscle and dieting to lose fat — commonly known as bulking and cutting.

Much of this advice comes from fitness influencers who appear to have the results to back it up. They might have millions of followers, an encyclopedic knowledge of exercise science and a physique that makes their recommendations hard to ignore. But looking strong doesn’t necessarily indicate whether someone’s methods are safe, sustainable or even responsible for the results we see.

People also approach muscle growth with different goals. Some want to lift heavier or perform better in a sport, while others are thinking about their long-term health or simply want to look stronger. Whatever the motivation, the same questions apply: What actually helps muscles grow, and how far should one go to optimize that process?

To find out, we spoke with Dr. Irvin Sulapas, a primary care sports medicine physician at Houston Methodist, about the biology behind muscle growth and which training, nutrition and recovery habits matter most over time.

What actually happens when muscles grow

Despite the name, “building” muscle doesn’t mean our bodies are creating new muscle fibers. We’re born with the fibers we’ll have throughout our lives, according to Dr. Sulapas, and muscle growth occurs as those existing fibers become bigger and stronger, a process known as hypertrophy.

The number of fibers can vary considerably. In one study published in the Journal of Applied Physiology, researchers estimated that certain participants had more than twice as many biceps fibers as others. Yet, bodybuilders in the study didn’t have more fibers overall than untrained participants. Their muscles were larger primarily because their individual fibers were larger.

Resistance training gives those fibers a reason to grow. Lifting creates tension in the muscles and triggers a repair and remodeling process that helps the fibers grow and become better equipped to handle that demand.

But muscles adapt. If nothing about a workout changes, they no longer have the same reason to keep growing — that’s where progressive overload comes in.

“Progressive overload is the principle of increasing the demand placed on your muscles and continually challenging them,” Dr. Sulapas says. “If you’re lifting the same amount of weight regularly, the tissue has no reason to keep adapting because you’re used to carrying that weight.”

A mistake made by beginners and seasoned weightlifters alike

One reason a new workout routine may not stick is that people often begin highly motivated and try to do too much too soon. But beginners aren’t the only ones who make this mistake. Even experienced weightlifters may return from an illness, injury or extended break expecting to pick up where they left off, only to discover that the same workout feels much harder than it did before.

Some soreness after exercising is normal, especially when you’re trying an unfamiliar movement or returning after time away. This is known as delayed onset muscle soreness, or DOMS. But using more weight or intensity than your body is ready to handle can be extremely uncomfortable, make it harder to maintain proper form and increase your risk of injury.

“You don’t sign up for a 10K if you haven’t run yet,” Dr. Sulapas says. “The same rules apply with weightlifting. You’ve got to start somewhere.”

For someone new to strength training, Dr. Sulapas recommends beginning with a modest program that prioritizes form and technique. That might mean completing two or three full-body workouts each week or dividing those sessions among different muscle groups. The exact format matters less at first than learning how to perform each movement comfortably and consistently.

Once you've built that foundation, you can increase the demands of your workouts as your body allows.

“Natural muscle growth is slow. Weight training is a marathon of sorts. It’s more about consistency, not necessarily doing as much as possible.”

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Dr. Irvin Sulapas, primary care sports medicine physician

How much muscle you can realistically expect to gain over time

For someone who is relatively new to consistent strength training, Dr. Sulapas says gaining about half a pound to a pound of muscle per month may be a realistic estimate.

“That’s more toward the upper limit for a well-trained beginner,” he says. “But it tapers over the years.”

That slowdown is one reason people who are new to resistance training may notice results more quickly than those who have been lifting consistently for years. A beginner’s muscles are responding to a relatively new stimulus, leaving more room for early growth. As the body becomes better trained and moves closer to its natural potential, additional gains typically become harder to achieve.

There also isn’t one rate that applies to everyone. Age, genetics, starting muscle mass and training experience can all influence how quickly someone responds. Even two people who follow similar workout programs may not gain the same amount of muscle or develop the same physique.

The more useful comparison is whether your own strength, performance and muscle size are gradually improving over time.

You don’t need to ‘bulk and cut’ to build significant muscle

For some competitive bodybuilders, building muscle isn’t the only goal. They’re also trying to achieve the extremely lean, muscular appearance required onstage. That’s where bulking and cutting often enter the picture.

During a bulk, someone intentionally eats more calories than their body uses to support muscle growth, knowing that they’ll likely gain some body fat along the way. A cut typically follows, with calories reduced in an effort to lose the added fat while preserving as much muscle as possible. But most people don’t need to put their bodies through dramatic weight fluctuations to get stronger.

“For strength, you don’t necessarily need to bulk or cut,” Dr. Sulapas says. “That’s more if you’re trying to do physique competitions.”

Smaller, controlled changes in calorie intake may help someone work toward a specific fitness or appearance goal. An endurance athlete, for instance, might temporarily increase their carbohydrate intake while training for a race to ensure their muscles have enough stored energy. Problems are more likely when bulking and cutting become an aggressive cycle of overeating followed by significant restriction. Dr. Sulapas says this can blur the line between a fitness strategy and disordered eating, particularly for people already struggling with body-image concerns.

“It turns into this binge-restrict cycle,” he says. “For some people, you’re actually at a higher risk of creating a clinical disordered eating issue.”

Repeated cycles may also cause what Dr. Sulapas calls “bulk creep,” a gradual accumulation of body fat when someone doesn’t lose all the fat gained during each bulk. The difference may be small after one cycle but become more noticeable over several years.

Aggressive cutting carries its own risks. Consistently consuming less energy than the body needs can lead to low energy availability and, in women, may contribute to menstrual irregularities, according to Dr. Sulapas.

It’s possible to build muscle and lose weight at the same time

Although building muscle and losing weight can seem like competing goals, it is possible to do both at the same time. This process, sometimes called body recomposition, involves gaining muscle while losing body fat.

It’s one reason the number on the scale may not tell the whole story when someone begins strength training, Dr. Sulapas says. A person could lose fat and gain muscle without seeing a dramatic change in their total body weight. In some cases, the number may stay the same or even increase slightly while their clothes fit differently and their body appears leaner or more muscular, he says.

“Don’t get hyperfixated on the number on the scale,” says Dr. Sulapas. “You may have gained two pounds, but your clothes started feeling looser. Maybe you’re gaining muscle mass and losing fat. That’s still a positive.”

The familiar claim that “muscle weighs more than fat” isn’t literally true, since a pound is a pound. The difference is that muscle is denser than fat, meaning a pound of muscle takes up less space in the body than a pound of fat. That can help explain why someone’s appearance and measurements may change even when their weight does not.

A body composition scale may provide a more complete picture by estimating how much of your weight comes from body fat and fat-free mass. Although these readings aren’t exact, tracking them under similar conditions over time may help reveal changes that a standard scale cannot.

Protein matters, but it can’t build muscle by itself

Protein is having quite a moment. It’s added to practically everything these days, from chips and ice cream to candy, popcorn and drinks — but protein can only support muscle growth after training gives your muscles a reason to grow in the first place.

“The primary driver is resistance training,” Dr. Sulapas says. “Without it, no amount of protein will build any muscle. You can’t just take protein shakes and not work out.”

The recommended dietary allowance for the average adult is 0.36 grams of protein per pound of body weight each day. However, people who regularly perform intense resistance training may need up to about 0.77 grams per pound. For a 150-pound adult, that's between 54 and 116 grams of protein daily, depending on activity level and fitness goals.

A full gram per pound is rarely necessary, even for active adults and athletes. Eating more protein than your body needs may add excess calories, cause digestive issues or crowd out more nutrient-dense foods from your diet. Spreading protein across several meals may also help support muscle repair while reducing the likelihood of digestive discomfort.

Sleep and recovery matter, too. Most adults should aim for seven to nine hours of quality sleep each night and give trained muscles adequate time to repair.

“If you want to build more muscle, you need good sleep,” Dr. Sulapas says. “Chronic sleep restriction actually blunts strength and hypertrophy gains.”

Are any muscle-building supplements worth taking?

Among the countless muscle-building powders, pills and proprietary blends available, Dr. Sulapas says relatively few have strong evidence behind them.

Creatine monohydrate is the notable exception.

“The most well-studied, evidence-based supplement is creatine,” he says. “Around three to five grams a day has been well studied for strength and muscle gain, and it has a good safety profile in healthy individuals, including with long-term use.”

Creatine is a substance the body naturally produces and stores primarily in muscle, where it provides quick energy during brief, high-intensity activities such as lifting weights. Supplementing with it may help someone lift more weight or complete more repetitions, giving the muscles a greater training stimulus over time. It isn’t appropriate for everyone, however, including some people with kidney or liver issues, so talk to your doctor before adding it to your routine.

Protein powders can also be useful, mostly for convenience. They offer another way to meet your protein needs when a full meal isn’t practical, though Dr. Sulapas emphasizes that they shouldn’t regularly replace a balanced diet.

“Sometimes life gets at you, and you just have to do a protein shake, which is fine, but nothing substitutes real food,” he says.

Caffeine may provide a modest performance boost before a workout as well. For people who tolerate it, Dr. Sulapas says a simple cup of coffee may work just as well as many more expensive pre-workout products.

Products marketed as “testosterone boosters,” “natural steroids” or alternatives to anabolic drugs raise more concern.

“Testosterone boosters universally do not have evidence of efficacy,” Dr. Sulapas says. “The doses may be too high or too low, and they’re often based on theoretical benefits rather than something tried and true in healthy populations.”

Selective androgen receptor modulators, commonly known as SARMs, are another red flag. No SARM has been approved by the Food and Drug Administration, and products sold online may contain different amounts or substances than their labels claim.

If you choose to use a supplement, look for a product that contains a well-studied ingredient in a clearly listed dose and has been independently tested by a reputable third party.

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Looking strong isn’t always the same as being healthy

A muscular, lean physique can look like the picture of health, but it doesn’t reveal what may be happening inside the body. Anabolic steroids, SARMs and other performance-enhancing drugs may help someone build muscle faster than their body naturally could while also affecting the heart, liver and endocrine system.

“You may have someone who looks like a big bodybuilder, but they may have organ issues or cardiovascular problems,” Dr. Sulapas says. “No one’s going to see how bad their blood pressure is as long as they look good.”

Anabolic steroid use has been associated with higher rates of heart attack, blood clots, arrhythmias and heart failure. It can also alter cholesterol levels, suppress the body’s natural hormone production and increase the risk of liver problems, depending on the substance used. Some of these effects can persist after someone stops taking the drugs.

Frustration with slow natural growth can make these shortcuts tempting, and social media may add to that pressure. Fitness content often shows people in favorable lighting, posing at the right angle and sharing moments when they look their best. What viewers don’t always see is how many years it took to achieve that physique, how restrictive someone’s routine may be or whether performance-enhancing substances played a role.

For some people, that steady exposure can contribute to muscle dysmorphia, sometimes informally called “bigorexia.” Someone with muscle dysmorphia may become preoccupied with the belief that their body isn’t muscular enough, even when others see them as fit or highly muscular. That distorted self-image can drive increasingly rigid workouts, eating patterns or the use of risky substances in pursuit of a body that never feels big enough.

In a meta-analysis of 187 studies published in the Annals of Epidemiology, researchers found that nonmedical anabolic steroid use may be more common than many people realize. An estimated 18.4% of recreational gym users, weightlifters and bodybuilders had used anabolic steroids at some point in their lives. Even among high school students, the estimated lifetime rate was 2.3%.

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The best way to build muscle is to play the long game

Building muscle may be the initial goal, but maintaining it becomes increasingly important as we age. Starting around age 30, adults can naturally lose between 3% and 8% of their muscle mass per decade. Over time, Dr. Sulapas says our reasons for strength training often change as we get older.

“When I was in my 20s, I was trying to lift just to get strong and see how far I could go,” he says. “Now, I want to be healthy in my 60s. The goalposts have changed.”

Eventually, progress may mean maintaining your strength, listening when your body needs a lighter workout or prioritizing joint and tendon health. Free weights, machines, resistance bands and body-weight exercises can all work. What matters is choosing an approach that fits your abilities and that you’re willing to continue.

“If you hate dumbbells but you’re fine with the machines, great,” Dr. Sulapas says. “Resistance is resistance. Whatever you like doing, that’s the one you should stick with.”

After all, the perfect workout program isn’t particularly useful if it leaves you injured, burned out or unwilling to return. The routines most likely to build lasting strength are the ones that can change with your body and remain part of your life.

“The single biggest predictor of someone who, in 10 to 20 years, is stronger and healthier isn’t how hard they trained in any given month,” Dr. Sulapas says. “It’s whether they’re still training, period.”