Study analysis · Journal of strength and conditioning research · 2025
Older women don’t need protein shakes to build muscle—just 72g a day.
Older women who lift weights gain more muscle when they eat about 1.1 grams of protein per kilogram of body weight each day, but eating more doesn’t help much.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at whether older women who lift weights and eat more protein gain more muscle—and found that those who ate more protein tended to gain a little more muscle. But it didn’t prove that the protein caused the gain; maybe those women were just healthier overall or ate more calories.
What’s the bottom line?
This study looked at older women who started lifting weights and found that those who ate more protein gained more muscle — but only up to a point.
How strong is this study?
The study measured muscle and protein intake pretty carefully, but it didn’t control for other things like how much sleep the women got or what else they ate. That means we can’t be totally sure the protein was the reason for the muscle gain—it’s like noticing people who wear sneakers run faster, but maybe they just train more.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
22 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=97)+7.7/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational study with no randomization or control group; it measures associations between protein intake and muscle mass changes over time, but cannot rule out confounding factors such as physical activity levels, overall diet, or pre-existing health conditions.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the provided text.
The study lacks any declared funding source, conflict of interest statement, or author affiliations with industry entities. While this absence may indicate independence, it also raises concerns about transparency and potential undisclosed biases.
Key takeaways
- 01
Women who ate about 1.1 grams of protein per kilogram of body weight each day gained more muscle than those who ate less.
- 02
Eating more than that didn't show extra benefit.
- 03
Protein intake didn't affect fat loss.
- 04
For an older woman weighing 65 kg (about 143 lbs), this means eating around 72 grams of protein per day may help her build more muscle from weight training — but eating way more won't help much more.
Surprising findings
- Protein intake above 1.1 g/kg/day showed no additional muscle gain benefit.Most fitness influencers recommend 1.6–2.2 g/kg for muscle building, even for older adults. This study suggests that’s overkill for untrained older women.
- No association between protein and fat loss despite 24 weeks of training.High-protein diets are often marketed as fat-burning tools. This study shows that in older women, protein’s role is purely anabolic—not catabolic.
Practical takeaways
An older woman weighing 65 kg should aim for about 72g of protein daily (1.1 g/kg) through meals like eggs, Greek yogurt, chicken, beans, and cottage cheese.
This is based on observational data—no randomization or protein manipulation. Other lifestyle factors likely matter more.
medium confidenceWhy this study matters
The 1.1g/kg Breakpoint
The study found a clear threshold at 1.1 grams of protein per kilogram of body weight per day—women consuming at least this amount gained significantly more muscle during 24 weeks of resistance training. Below this, gains plateaued, and above it, no extra benefit was seen.
Most people think 'more protein = more muscle,' but this shows there’s a sweet spot—even for older adults. It challenges the idea that protein supplements are necessary for optimal results.
Protein Doesn’t Burn Fat
Despite higher protein intake, there was no significant link to body fat loss. The women lost or gained fat based on other factors—not protein consumption.
This flips the script on the common belief that high protein = fat loss. For older women, protein’s job is muscle building, not fat burning.
Weak but Real Correlation
The correlation between protein intake and muscle gain was statistically significant but modest (r = 0.23), meaning protein explains only a small part of why some women gained more muscle than others.
Even with perfect protein intake, other factors—sleep, recovery, training form, genetics—play a bigger role. This humbles the protein obsession.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at older women who started lifting weights and found that those who ate more protein gained more muscle — but only up to a point.
Research results
Women who ate about 1.1 grams of protein per kilogram of body weight each day gained more muscle than those who ate less. Eating more than that didn't show extra benefit. Protein intake didn't affect fat loss.
What this means - more context
For an older woman weighing 65 kg (about 143 lbs), this means eating around 72 grams of protein per day may help her build more muscle from weight training — but eating way more won't help much more.
This study examined whether habitual protein intake influences skeletal muscle mass gains in previously untrained older women undergoing 24 weeks of resistance training.
Among 97 healthy, untrained older women (mean age 68.6 years), higher daily protein intake was positively correlated with increases in skeletal muscle mass, with a statistically significant breakpoint at approximately 1.1 g/kg/day. No significant association was found between protein intake and changes in body fat mass.
Methods Used
Retrospective analysis of 97 older women (68.6 ± 6.3 years) undergoing 24 weeks of standardized resistance training (3x/week, 8 exercises, 3 sets of 8–15 reps). Protein intake was assessed via 24-hour dietary recall; skeletal muscle mass and body fat mass were measured using dual-energy X-ray absorptiometry. Statistical analyses included Pearson correlation and segmented regression.
Main Finding
A positive correlation was found between daily protein intake and skeletal muscle mass gains (r = 0.23, p = 0.022), with a significant breakpoint at 1.1 g/kg/day (95% CI: 0.9–1.3). No significant association was observed between protein intake and body fat mass changes (p > 0.05).
Confidence Level
Moderate — findings are based on a well-defined intervention and objective body composition measures, but the retrospective design and lack of randomization limit causal inference.
Study Flags
Red Flags
- •Retrospective design with no prospective protein control
- •No randomization or intervention on protein intake
- •Small effect size (r = 0.23) suggests protein explains only a minor portion of muscle gain variability
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Protein intake above 1.1 g/kg/day showed no additional muscle gain benefit.
Most fitness influencers recommend 1.6–2.2 g/kg for muscle building, even for older adults. This study suggests that’s overkill for untrained older women.
Practical Takeaways
An older woman weighing 65 kg should aim for about 72g of protein daily (1.1 g/kg) through meals like eggs, Greek yogurt, chicken, beans, and cottage cheese.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at whether older women who lift weights and eat more protein gain more muscle—and found that those who ate more protein tended to gain a little more muscle. But it didn’t prove that the protein caused the gain; maybe those women were just healthier overall or ate more calories.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Use of dual-energy X-ray absorptiometry (DXA) for accurate muscle mass measurement
- Moderate sample size (n=97) for an observational study
- Use of segmented regression to identify a potential breakpoint in protein intake
Weaknesses
- No randomization or control group—cannot isolate protein's effect from other variables
- Dietary intake assessed by single 24-hour recall—prone to recall bias and poor representation of habitual intake
- Retrospective design—protein intake measured after muscle changes occurred, risking reverse causality
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at older women who started lifting weights and found that those who ate more protein gained more muscle — but only up to a point.
Research results
Women who ate about 1.1 grams of protein per kilogram of body weight each day gained more muscle than those who ate less. Eating more than that didn't show extra benefit. Protein intake didn't affect fat loss.
What this means - more context
For an older woman weighing 65 kg (about 143 lbs), this means eating around 72 grams of protein per day may help her build more muscle from weight training — but eating way more won't help much more.
This study examined whether habitual protein intake influences skeletal muscle mass gains in previously untrained older women undergoing 24 weeks of resistance training.
Among 97 healthy, untrained older women (mean age 68.6 years), higher daily protein intake was positively correlated with increases in skeletal muscle mass, with a statistically significant breakpoint at approximately 1.1 g/kg/day. No significant association was found between protein intake and changes in body fat mass.
Methods Used
Retrospective analysis of 97 older women (68.6 ± 6.3 years) undergoing 24 weeks of standardized resistance training (3x/week, 8 exercises, 3 sets of 8–15 reps). Protein intake was assessed via 24-hour dietary recall; skeletal muscle mass and body fat mass were measured using dual-energy X-ray absorptiometry. Statistical analyses included Pearson correlation and segmented regression.
Main Finding
A positive correlation was found between daily protein intake and skeletal muscle mass gains (r = 0.23, p = 0.022), with a significant breakpoint at 1.1 g/kg/day (95% CI: 0.9–1.3). No significant association was observed between protein intake and body fat mass changes (p > 0.05).
Confidence Level
Moderate — findings are based on a well-defined intervention and objective body composition measures, but the retrospective design and lack of randomization limit causal inference.
Study Flags
Red Flags
- •Retrospective design with no prospective protein control
- •No randomization or intervention on protein intake
- •Small effect size (r = 0.23) suggests protein explains only a minor portion of muscle gain variability
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Protein intake above 1.1 g/kg/day showed no additional muscle gain benefit.
Most fitness influencers recommend 1.6–2.2 g/kg for muscle building, even for older adults. This study suggests that’s overkill for untrained older women.
Practical Takeaways
An older woman weighing 65 kg should aim for about 72g of protein daily (1.1 g/kg) through meals like eggs, Greek yogurt, chicken, beans, and cottage cheese.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at whether older women who lift weights and eat more protein gain more muscle—and found that those who ate more protein tended to gain a little more muscle. But it didn’t prove that the protein caused the gain; maybe those women were just healthier overall or ate more calories.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Use of dual-energy X-ray absorptiometry (DXA) for accurate muscle mass measurement
- Moderate sample size (n=97) for an observational study
- Use of segmented regression to identify a potential breakpoint in protein intake
Weaknesses
- No randomization or control group—cannot isolate protein's effect from other variables
- Dietary intake assessed by single 24-hour recall—prone to recall bias and poor representation of habitual intake
- Retrospective design—protein intake measured after muscle changes occurred, risking reverse causality
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study measured muscle and protein intake pretty carefully, but it didn’t control for other things like how much sleep the women got or what else they ate. That means we can’t be totally sure the protein was the reason for the muscle gain—it’s like noticing people who wear sneakers run faster, but maybe they just train more.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
22 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=97)+7.7/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational study with no randomization or control group; it measures associations between protein intake and muscle mass changes over time, but cannot rule out confounding factors such as physical activity levels, overall diet, or pre-existing health conditions.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the provided text.
The study lacks any declared funding source, conflict of interest statement, or author affiliations with industry entities. While this absence may indicate independence, it also raises concerns about transparency and potential undisclosed biases.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Shawn Baker MD cite this study, drawing 2 claims from it.
Authored by
12 researchersIf this is your work, this is how we attribute it on Fit Body Science. Alex Silva Ribeiro is listed as the lead author.
- Universidade Estadual de Londrina
Cited in 16 claims · 2 videos