- Aug 15, 2018
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# Protein Targets While Training: What Does the Research Actually Support?
We've all seen the protein debates. One lifter says there's a magic number everybody needs to hit. Another says anything above an ordinary diet is wasted. Somebody else has a spreadsheet that makes eating sound like a second job.
For this thread, let's leave the slogans at the door and look at what researchers actually measured. Protein is relevant to training adaptation, but a number pulled from a study isn't automatically a universal target. The interesting questions are where the evidence begins to level off, who was studied, and what the experiments can and cannot tell us.
**The big study people keep quoting**
Morton and colleagues published a systematic review and meta-analysis in the *British Journal of Sports Medicine* in 2018. It pooled 49 studies involving 1,863 participants who were doing resistance exercise training. Across those studies, additional protein supplementation was associated with modest extra gains in fat-free mass, strength, and certain measures of muscle size. This was an average research finding, not a promise about any particular lifter.
The headline number was about **1.6 grams of protein per kilogram of body weight per day**. In the authors' statistical model, gains in fat-free mass did not keep rising reliably above roughly that intake. Crucially, the estimated breakpoint had a wide confidence interval, reported as 1.03 to 2.20 grams per kilogram per day. So treating 1.6 as a precise biological switch misses the uncertainty in the estimate.
The studies included different ages, training backgrounds, diets, and protocols—not exclusively experienced bodybuilders. Morton and colleagues also reported differences by training status and age. That limits one-size-fits-all interpretations.
**Why you also see the 1.4–2.0 range**
The 2017 *Journal of the International Society of Sports Nutrition* position stand by Jäger and colleagues discussed **1.4–2.0 grams per kilogram per day** as a range supported for most exercising individuals in the context of maintaining or building muscle mass. That's a scientific position statement: it gathers and interprets available evidence rather than reporting a single new randomized trial.
Those publications aren't necessarily arguing. Estimating where average added benefit tapers off differs from describing a broader evidence-supported range. Biological variation doesn't disappear because a number is memorable.
Separate **total daily intake** from **supplementation**. Trials adding protein compare groups with different starting diets. The resulting intake difference matters more than the label on the added food or drink.
**What did researchers mean by “more muscle”?**
In the Morton analysis, the average additional increase in fat-free mass attributed to protein supplementation alongside resistance training was **0.30 kg**, with a 95% confidence interval from **0.09 to 0.52 kg**. The pooled additional one-repetition-maximum strength change was **2.49 kg**, with a 95% confidence interval from **0.64 to 4.33 kg**.
Those are real results, but the context matters. Fat-free mass includes more than contractile muscle tissue. A strength test reflects technique and neurological learning as well as tissue changes. Different trials also ran for different lengths of time. Reading those outcome labels carefully is far more informative than turning a small pooled average into an exaggerated transformation claim.
Pooling studies makes small signals easier to detect, but it also combines different participants and methods. Protein availability matters without determining training results by itself.
**What about timing around a workout?**
This is where forum arguments get especially heated. Schoenfeld, Aragon, and Krieger published a 2013 meta-analysis in the *Journal of the International Society of Sports Nutrition* examining protein timing in relation to resistance training. Their analysis found that once total daily protein intake was considered, the apparent association between precise timing and hypertrophy was substantially weakened. Total protein intake was the stronger predictor in their models.
That result doesn't prove timing never matters under any circumstances. It does challenge the internet's favourite dramatic version of an incredibly narrow post-workout window. The evidence was also constrained by the trials available at the time, including differences in how total protein was controlled. That's an important distinction between “not clearly established” and “biologically impossible.”
Acute muscle protein synthesis studies aren't interchangeable with months-long strength or muscle-size measurements. Short laboratory responses help explain mechanisms but cannot directly quantify long-term outcomes.
**The populations behind the numbers**
Consider two people doing resistance training: one is new to lifting, while the other has years of structured experience. Their training responses are unlikely to be identical. Now add age differences, baseline diet, total energy intake, and the way each study measures lean tissue. All of those factors can influence how confidently a published average applies beyond its sample.
Research involving trained lifters is particularly interesting to this community, but we shouldn't quietly pretend every participant in every protein study was advanced. Some studies recruit recreationally active adults; others involve older adults or people beginning a training programme. The Morton paper explicitly examined training status, yet the subgroup results still deserve the same caution as any comparison across smaller groups.
An intake range in a paper is a **description of evidence**, not an instruction. We're discussing published findings, not personalized meal plans.
**My takeaway as a forum reader**
The most defensible conclusion is surprisingly ordinary: protein intake matters in resistance-training research; the benefits of adding more appear to diminish as total intake rises; and the exact point where that happens varies across people and study designs. The dramatic “more is always better” claim goes beyond the evidence. So does the claim that all intake ranges discussed in sports-nutrition papers are arbitrary.
If you're interested in digging into the original work, the useful starting points are Morton et al., *British Journal of Sports Medicine* (2018); Jäger et al., *Journal of the International Society of Sports Nutrition* (2017); and Schoenfeld, Aragon and Krieger, *Journal of the International Society of Sports Nutrition* (2013). The methods and limitations are worth reading alongside the abstracts.
This is exactly the kind of subject where the forum can add value: experienced lifters can compare how they interpret the literature without mistaking individual anecdotes for controlled evidence. I'd especially like to hear where people think the research gets oversimplified.
1. Which finding surprised you more: the modest average effect sizes in Morton et al., or the uncertainty around the widely quoted 1.6 g/kg breakpoint?
2. When you read protein studies, how much weight do you give to participants' training experience and baseline diet before applying the conclusions to lifting culture?
3. Do you think online debates spend too much time on exact protein timing and too little time on how long-term training outcomes were actually measured?
— OLYMPIC
We've all seen the protein debates. One lifter says there's a magic number everybody needs to hit. Another says anything above an ordinary diet is wasted. Somebody else has a spreadsheet that makes eating sound like a second job.
For this thread, let's leave the slogans at the door and look at what researchers actually measured. Protein is relevant to training adaptation, but a number pulled from a study isn't automatically a universal target. The interesting questions are where the evidence begins to level off, who was studied, and what the experiments can and cannot tell us.
**The big study people keep quoting**
Morton and colleagues published a systematic review and meta-analysis in the *British Journal of Sports Medicine* in 2018. It pooled 49 studies involving 1,863 participants who were doing resistance exercise training. Across those studies, additional protein supplementation was associated with modest extra gains in fat-free mass, strength, and certain measures of muscle size. This was an average research finding, not a promise about any particular lifter.
The headline number was about **1.6 grams of protein per kilogram of body weight per day**. In the authors' statistical model, gains in fat-free mass did not keep rising reliably above roughly that intake. Crucially, the estimated breakpoint had a wide confidence interval, reported as 1.03 to 2.20 grams per kilogram per day. So treating 1.6 as a precise biological switch misses the uncertainty in the estimate.
The studies included different ages, training backgrounds, diets, and protocols—not exclusively experienced bodybuilders. Morton and colleagues also reported differences by training status and age. That limits one-size-fits-all interpretations.
**Why you also see the 1.4–2.0 range**
The 2017 *Journal of the International Society of Sports Nutrition* position stand by Jäger and colleagues discussed **1.4–2.0 grams per kilogram per day** as a range supported for most exercising individuals in the context of maintaining or building muscle mass. That's a scientific position statement: it gathers and interprets available evidence rather than reporting a single new randomized trial.
Those publications aren't necessarily arguing. Estimating where average added benefit tapers off differs from describing a broader evidence-supported range. Biological variation doesn't disappear because a number is memorable.
Separate **total daily intake** from **supplementation**. Trials adding protein compare groups with different starting diets. The resulting intake difference matters more than the label on the added food or drink.
**What did researchers mean by “more muscle”?**
In the Morton analysis, the average additional increase in fat-free mass attributed to protein supplementation alongside resistance training was **0.30 kg**, with a 95% confidence interval from **0.09 to 0.52 kg**. The pooled additional one-repetition-maximum strength change was **2.49 kg**, with a 95% confidence interval from **0.64 to 4.33 kg**.
Those are real results, but the context matters. Fat-free mass includes more than contractile muscle tissue. A strength test reflects technique and neurological learning as well as tissue changes. Different trials also ran for different lengths of time. Reading those outcome labels carefully is far more informative than turning a small pooled average into an exaggerated transformation claim.
Pooling studies makes small signals easier to detect, but it also combines different participants and methods. Protein availability matters without determining training results by itself.
**What about timing around a workout?**
This is where forum arguments get especially heated. Schoenfeld, Aragon, and Krieger published a 2013 meta-analysis in the *Journal of the International Society of Sports Nutrition* examining protein timing in relation to resistance training. Their analysis found that once total daily protein intake was considered, the apparent association between precise timing and hypertrophy was substantially weakened. Total protein intake was the stronger predictor in their models.
That result doesn't prove timing never matters under any circumstances. It does challenge the internet's favourite dramatic version of an incredibly narrow post-workout window. The evidence was also constrained by the trials available at the time, including differences in how total protein was controlled. That's an important distinction between “not clearly established” and “biologically impossible.”
Acute muscle protein synthesis studies aren't interchangeable with months-long strength or muscle-size measurements. Short laboratory responses help explain mechanisms but cannot directly quantify long-term outcomes.
**The populations behind the numbers**
Consider two people doing resistance training: one is new to lifting, while the other has years of structured experience. Their training responses are unlikely to be identical. Now add age differences, baseline diet, total energy intake, and the way each study measures lean tissue. All of those factors can influence how confidently a published average applies beyond its sample.
Research involving trained lifters is particularly interesting to this community, but we shouldn't quietly pretend every participant in every protein study was advanced. Some studies recruit recreationally active adults; others involve older adults or people beginning a training programme. The Morton paper explicitly examined training status, yet the subgroup results still deserve the same caution as any comparison across smaller groups.
An intake range in a paper is a **description of evidence**, not an instruction. We're discussing published findings, not personalized meal plans.
**My takeaway as a forum reader**
The most defensible conclusion is surprisingly ordinary: protein intake matters in resistance-training research; the benefits of adding more appear to diminish as total intake rises; and the exact point where that happens varies across people and study designs. The dramatic “more is always better” claim goes beyond the evidence. So does the claim that all intake ranges discussed in sports-nutrition papers are arbitrary.
If you're interested in digging into the original work, the useful starting points are Morton et al., *British Journal of Sports Medicine* (2018); Jäger et al., *Journal of the International Society of Sports Nutrition* (2017); and Schoenfeld, Aragon and Krieger, *Journal of the International Society of Sports Nutrition* (2013). The methods and limitations are worth reading alongside the abstracts.
This is exactly the kind of subject where the forum can add value: experienced lifters can compare how they interpret the literature without mistaking individual anecdotes for controlled evidence. I'd especially like to hear where people think the research gets oversimplified.
1. Which finding surprised you more: the modest average effect sizes in Morton et al., or the uncertainty around the widely quoted 1.6 g/kg breakpoint?
2. When you read protein studies, how much weight do you give to participants' training experience and baseline diet before applying the conclusions to lifting culture?
3. Do you think online debates spend too much time on exact protein timing and too little time on how long-term training outcomes were actually measured?
— OLYMPIC