What Drives More Muscle Growth, Your Training or Daily Protein Intake? (What Science Really Shows)

We all know that resistance training is a proven way to get stronger and build more muscle. Many of us also consume extra protein in the form of shakes, powders, or high-protein foods in hopes of accelerating these gains.

If you listen to everything you see on social media, you'd think that simply eating more protein is the formula for bigger, stronger muscles. But you'd be severely misguided if you did.

And recent research confirms that while protein does play a role, it's not the magic bullet we've been led to believe.

Protein is often described as the building block of muscle, and that’s an accurate statement. But the real question is, how much does extra protein actually help when combined with resistance training? Over the years, studies have produced mixed results^(1,2).

Some show clear benefits, while others suggest little added effect. These discrepancies may come down to differences in who was studied, young or old, trained or untrained, and how much protein they were consuming to begin with. But this leaves many people confused and wondering, does consuming more protein improve results and if so, how much?

To resolve this confusion, researchers conducted the largest and most comprehensive analysis to date. They examined data from 49 separate studies involving over 1,800 participants⁽³⁾.

Why is this study important?

This type of study is called a meta-analysis, which works by pooling data and results from many smaller trials to look for consistent patterns. By pooling all this data, researchers can cut through the noise and give us clearer answers on what scientific research means across large numbers of people.

This review confirmed that while protein supplementation does improve gains in both muscle mass and strength when combined with resistance training, the effect is modest compared to the impact of training by itself.

In other words, your training is the primary force behind muscle and strength gains. It's the engine powers muscle growth, while protein is the fuel that helps the engine run efficiently. Without the engine, the fuel won’t take you anywhere. But not everyone benefits from more protein equally.

Who Benefits Most from Extra Protein?

Protein had the greatest effect in:

• People who already had training experience. These individuals already made the easy beginner gains, so protein helped them continue progressing.
• Younger adults. Their bodies respond more efficiently to both exercise and protein.
• Older adults. Although they have more to gain in terms of preventing age-related muscle loss, the benefits were smaller. This is because most studies didn’t provide older participants with high enough protein doses to fully activate muscle growth.

These findings suggest that older adults may need larger, more consistent protein intakes to match the benefits seen in younger individuals. This is known as “anabolic resistance” which is defined as a decreased ability of skeletal muscle to synthesize protein (aka build muscle) in response to anabolic stimuli such as protein intake, exercise, and hormones that promote muscle growth⁽⁴⁾.

That’s especially important given that muscle loss with age (a condition called sarcopenia) can make everyday activities like walking, climbing stairs, or carrying groceries more difficult.

So, how much protein do you actually need to maximize your results?

The study found that 1.6 grams of protein per kilogram of body weight per day is the point at which muscle and strength gains plateau⁽⁵⁾. Consuming more doesn’t seem to provide additional benefit.

For reference, that’s roughly 112 grams of protein daily for someone who weighs 70 kilograms, which is about 154 pounds.

What this means is more protein doesn't equal better results. 

That's because there’s a limit to the amount of raw materials (protein and amino acids) your body can use each day to repair and build. Beyond that point, extra protein is like extra bricks left on the job site. 

Protein Adds a Boost, But Consistent Training Drives Strength Gains

On average, people who did resistance training alone increased their strength by about 27 kilograms (60 pounds) on common lifts⁽⁶⁾. Those who also consumed extra protein saw an additional 2.5-kilogram (about 5.5-pound) gain in strength, an improvement of roughly 9%⁽³⁾.

So while protein clearly helps, the bulk of strength gains come from doing the work, especially practicing exercises close to your maximum ability⁽⁷⁾.

This aligns with what we know about skill development. For example, if you want to get better at shooting basketballs, unless you’re out on the court practicing your shot every day, drinking a protein shake won’t make much difference.

What About Muscle Mass?

Resistance training alone led to an average gain of 1.1 kilograms (about 2.4 pounds) of muscle after at least six weeks. Protein added another 0.3 kilograms (0.7 pounds) on top of that. That may sound small, but over time those gains add up, particularly for trained individuals trying to push past a plateau.

Importantly, protein seemed to have a more consistent benefit in experienced lifters, who may require more precise nutritional support to continue improving. Now that we know how much helps, the next question is does when you take it or what kind you choose actually matter?

Timing and Type

The researchers found that when you consume protein, or what kind was less important than simply getting enough each day. Whether it was post-workout or spread across meals, the key factor was hitting that 1.6 g/kg daily target.

However, they noted that older adults may need more protein per meal to stimulate muscle growth, likely due to age-related changes in how the body processes and uses protein⁽⁸⁾.

What This Means for You

• Protein supplementation helps, especially if you're consistently engaging in resistance training.
• The workout itself is what drives the majority of change. 
• If building strength or muscle is your goal, aim for about 1.6 grams of protein per kilogram of body weight per day.
• More protein isn’t always better. Beyond a certain point, it doesn’t add much.
• Older adults and trained athletes benefit more from extra protein but may also require higher intakes to see results.
• Consistency in training matters more than timing of protein intake.

If you take away only one thing from all of this, let it be this:

Training is the engine. Protein is fuel. Without the engine, even the best fuel in the world doesn't make a huge difference in the outcome. If real progress is the goal, it always starts and ends with putting in the work. Make that the focus and support your efforts with eating nutrient-dense food, intelligent supplementation, sufficient hydration, and plenty of sleep.

With all that said, if you're looking hit that 1.6g per kg of bodyweight mark each and every day, supplementing protein is an easy way to help you reach that goal. And if you’re serious about hitting that daily protein target without overcomplicating your meals, STEEL Supplements has a fantastic line of whey and plant-based proteins that contain a full profile of the essential amino acids needed to build muscle.

Training hard deserves better fuel. Hit your daily protein goals with a flavor you'll actually crave. Grab your favorite or try a new one now!

References: 
    1.    Nissen SL, Sharp RL: Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. J Appl Physiol (1985) 94:651-9, 2003
    2.    Schoenfeld BJ, Aragon AA, Krieger JW: The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr 10:53, 2013
    3.    Morton RW, Murphy KT, McKellar SR, et al: A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine 52:376-384, 2018
    4.    Wall BT, Gorissen SH, Pennings B, et al: Aging is accompanied by a blunted muscle protein synthetic response to protein ingestion. PloS one 10:e0140903, 2015
    5.    Moore DR, Churchward-Venne TA, Witard O, et al: Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences 70:57-62, 2015
    6.    Babault N, Païzis C, Deley G, et al: Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein. J Int Soc Sports Nutr 12:3, 2015
    7.    Buckner SL, Jessee MB, Mattocks KT, et al: Determining strength: a case for multiple methods of measurement. Sports Medicine 47:193-195, 2017
    8.    Churchward-Venne TA, Holwerda AM, Phillips SM, et al: What is the optimal amount of protein to support post-exercise skeletal muscle reconditioning in the older adult? Sports Medicine 46:1205-1212, 2016