It’s estimated that there are over 2+ million scientific papers published each year, and this firehose only seems to intensify.

Even if you narrow your focus to fitness research, it would take several lifetimes to unravel the hairball of studies on nutrition, training, supplementation, and related fields.

This is why my team and I spend thousands of hours each year dissecting and describing scientific studies in articles, podcasts, and books and using the results to formulate our 100% all-natural sports supplements and inform our coaching services. 

And while the principles of proper eating and exercising are simple and somewhat immutable, reviewing new research can reinforce or reshape how we eat, train, and live for the better. 

Thus, each week, I’m going to share three scientific studies on diet, exercise, supplementation, mindset, and lifestyle that will help you gain muscle and strength, lose fat, perform and feel better, live longer, and get and stay healthier. 

This week, you’ll learn how much protein you should eat to maximize strength gain, the best rep range for gaining muscle and strength, and one weird way steroids make you stronger.

Here’s how much protein you should eat to maximize strength gain.

Source: “Synergistic Effect of Increased Total Protein Intake and Strength Training on Muscle Strength: A Dose-Response Meta-analysis of Randomized Controlled Trials” published on September 4, 2022 in Sports Medicine – Open.

You’ve probably heard that to maximize muscle growth, you have to eat around one gram of protein per pound of body weight per day.

This is a solid rule of thumb. 

But what if you don’t train for size specifically and instead lift weights primarily to gain strength?

Should you follow the same heuristic, or do protein requirements change?

That’s what scientists at Waseda University wanted to investigate when they conducted a meta-analysis of 82 randomized controlled trials (the “gold standard” of scientific research) examining the effects of protein intake on strength gain. 

They found that strength gain and protein intake share a dose-response relationship. In other words, the more protein you eat, the more strength you gain (to a point).

Specifically, the researchers found that strength gain increases by ~0.7% every time you increase your protein intake by 0.05 grams per pound of body weight per day, provided you lift weights. In other words, about a 1% increase in strength for every additional 15 grams of protein you eat. 

This strength gain occurs irrespective of age, sex, baseline protein intake, added protein intake, or body part and continues until your intake reaches ~0.7 grams of protein per pound of body weight per day. At this point, eating more protein won’t help you gain more strength. 

(It’s also worth noting that people still got stronger when eating as little as 0.2 grams of protein per pound of body weight per day, but they gained much more when they ate more protein.)

Thus, if you train specifically to gain strength, eating at least ~0.7 grams of protein per pound of body weight per day is a good benchmark.

A quick disclaimer, though: Japan’s largest protein supplement manufacturer funded the study. When supplement companies fund research, many see it as a red flag because it increases the odds that financial interest will color the results.

I don’t think this is something you need to worry about in this instance, though. If the results had suggested that you had to eat gobs of protein to gain strength, I’d be more suspicious. 

However, ~0.7 grams of protein per pound of body weight per day is reserved by most weightlifters’ standards, which is why I think this study’s credibility probably isn’t cause for concern. You can easily get this much protein without using supplements, so it isn’t exactly a clarion call to buy whey protein.

Keep in mind, though, that there are other benefits to eating more protein than this. Namely, it might offer some benefits for muscle growth, workout recovery, and satiety, which is why I generally still recommend people shoot for 1 gram per pound of body weight per day. 

And if you want a clean, 100% natural, delicious protein powder to help you eat enough per day that’s naturally sweetened and flavored and contains no artificial dyes or other chemical junk, try Whey+ or Casein+

(Or if you aren’t sure if Whey+ protein powder or Casein+ protein powder is right for you, take the Legion Supplement Finder Quiz! In less than a minute, it’ll tell you exactly what supplements are right for you. Click here to check it out.)

TL;DR: To maximize strength gain, eat at least ~0.7 grams of protein per pound of body weight per day.

Find the Perfect Supplements for You in Just 60 Seconds

You don't need supplements to build muscle, lose fat, and get healthy. But the right ones can help. Take this quiz to learn which ones are best for you.

Take the Quiz

You can build muscle using almost any rep range, but lower rep ranges are better for gaining strength.

Source: “Effects of Resistance Training Performed with Different Loads in Untrained and Trained Male Adult Individuals on Maximal Strength and Muscle Hypertrophy: A Systematic Review” published on October 26, 2021 in International Journal of Environmental Research and Public Health.

One of the first lessons you learn as a new weightlifter is that to build muscle, you have to train with moderately heavy weights for moderately high reps.

Often, this means training with 60-to-85% of your one-rep max for 6-to-12 reps per set.

Lift heavier than this, older hands say, and you’ll gain more strength but less muscle, and lift lighter, and you’ll improve your endurance but not strength or aesthetics.

In reality, this is nonsense.

Evidence of this comes from a meta-analysis conducted by scientists at the Federal University of Juiz de Fora, in which researchers pored over the results of 23 studies involving 563 new and experienced male weightlifters.

Their results showed that lifting any amount of weight between 30 and 90% of your one-rep max is equally effective for building muscle. Stated differently, you can effectively build muscle in any rep range between 4 and 30+ reps per set.

The only proviso is that you have to train sufficiently hard. If you lift heavy weights, this requires that you train close to failure (within 1-to-3 reps), and if you lift light weights, it’s likely better to train all the way to failure.

Furthermore, the researchers found that heavy, moderate, and light weightlifting are equally effective at training type I and II muscle fibers. This is contrary to some people’s belief that heavier weights are better at training type II muscle fibers and lighter weights are better suited to training type I muscle fibers. 

The only significant difference between each type of training was that heavier weights were superior to light weights for gaining strength. There are likely two reasons this is the case:

1. Training with heavy weights allows you to practice lifting heavy weights regularly. And the more you practice a skill like heavy weightlifting, the better you become. 

In contrast, someone who regularly trains with lighter weights will have less practice lifting heavy weights, which will be reflected when they attempt a one-rep max test.

2. Training with heavy weights likely increases neural drive, which means it improves your brain’s ability to communicate with your muscles, allowing them to produce more force when required.

In the final analysis, then, training with heavier weights is probably slightly better than training with lighter weights: it helps you build the same amount of muscle and more strength, and it doesn’t require you to train all the way to failure to progress.   

Most folk also find it more enjoyable for a few reasons:

1. When you train with heavier weights, you can generally progress (increase the weights you lift) more regularly, which is motivating. 

2. Doing lower-rep sets feels less fatiguing. 

For instance, do a 20-rep set of squats that ends a rep or two shy of failure. And then imagine having to do a couple more sets like that plus a few 15-to-20-rep sets for a few more exercises, like the leg press and lunge. I do not like this workout, Sam-I-Am. 

3. Sets of more reps take longer to complete and tax your cardiovascular system more than sets of fewer reps, forcing you to take longer rest periods to catch your breath.

Together, this adds significant time to your workouts.

The downside to training with heavier weights is they beat up your soft tissues and joints more than lighter-weight training.

The solution is to do most of your training in a low rep range (e.g., ~4-to-8 reps per set) and the remainder in a higher rep range (e.g., ~8-to-12 reps per set).

This is how I personally like to organize my training, and it’s similar to the method I advocate in my fitness books for men and women, Bigger Leaner Stronger and Thinner Leaner Stronger

(If you aren’t sure if Bigger Leaner Stronger or Thinner Leaner Stronger is right for you or if another strength training program might be a better fit for your circumstances and goals, take Legion Strength Training Quiz, and in less than a minute, you’ll know the perfect strength training program for you. Click here to check it out.)

TL;DR: You can build muscle using any rep range between 4 and ~30 reps, but lower rep ranges are better for gaining strength and tend to be more enjoyable. 

Find the Best Diet for You in Just 60 Seconds

How many calories should you eat? What about "macros?" What foods should you eat? Take our 60-second quiz to get science-based answers to these questions and more.

Take the Quiz

Steroids make you stronger partly because you believe they make you stronger.

Source: “Anabolic steroids: the physiological effects of placebos” published on January 22, 1972 in Medicine & Science in Sports and Exercise.

There’s no doubt that steroids make you gain strength by helping you gain muscle inhumanly fast.

According to some scientists, however, this isn’t the only reason they help you push, pull, and squat heavy weights. For them, steroids also make you stronger because you believe they make you stronger.

A good example of this comes from a study by scientists at the University of Massachusetts.

The researchers put 15 varsity athletes on a strength training program and told them that those who gained the most strength on the seated and standing overhead press, bench press, and squat would be selected to participate in a subsequent trial in which the athletes would take steroids and continue training.

This, the researchers said, would allow them to measure how the drugs affected the athletes’ strength gain.

For the following 8 weeks, the athletes trained as hard as they could 5 days per week, driven by the chance of getting 5 weeks’ worth of free, legal “gear.”

The researchers chose the 6 most-improved athletes, who added an average combined total of ~22 lb to the 4 exercises during the initial 8 weeks of training, and told them they’d receive 10 mg of Dianabol (a powerful anabolic steroid) daily for the next 5 weeks.

In reality, the athletes didn’t receive steroids. Instead, they took a placebo with no performance-enhancing effects.

This didn’t stop them from gaining strength like the clappers, though.

Over the following 5 weeks, the athletes added an average combined total of ~99 lb to the 4 exercises. That’s more than 4 times the amount they added in the first 8 weeks, and all because they thought they were juicing.

Here are some graphs taken from the study illustrating these results:


Psychological Effects of Steroids on Strength Gain

Sadly, there’s probably no way to harness the placebo effect to help you gain strength faster.

The only real takeaway from this study, then, is that you’re almost certainly stronger than you think you are, so you can probably push yourself a little harder to gain strength. 

TL;DR: Some of the strength people gain from steroids is attributable to the placebo effect; they make you stronger because that’s what you expect.

+ Scientific References