Study analysis · Nutrition research · 2014
Drink this before lunch to lose 5 pounds more than soy protein in 12 weeks (study on 45 men)
For overweight men, drinking whey protein before lunch helps them eat less, lose more weight and fat, and even gain muscle, compared to soy protein.
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 gave one group of men whey protein and another group soy protein before lunch for 12 weeks. They found that the whey group felt less hungry and lost more weight than the soy group. But because only 45 men were in the study and some dropped out, we can't say for sure that whey works the same for everyone.
What’s the bottom line?
This study looked at whether drinking a protein shake before lunch helps overweight men eat less and lose weight. They compared whey protein (from milk) and soy protein. Men who had whey protein before lunch felt less hungry, ate fewer calories, lost more weight and fat, and gained more muscle than those who had soy protein.
How strong is this study?
The study was well-designed because they randomly split the men into two groups and no one knew which protein they were getting. This helps make sure the results are fair. However, more men dropped out of the soy group, which might have made the results look better for whey. So it's a good study, but not perfect.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
80 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=45)+4.0/20
- Follow-up+10/10
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- 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 554 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. The RCT design allows for causal inference, but limitations include small sample size (n=45), unbalanced groups after dropout (WPC:26 vs SPI:19), dropout only in the SPI group, single sex (men), and free-living conditions with potential confounding. Therefore, causation is supported but with moderate confidence.
No Conflicts
No conflicts of interest identified
No conflicts of interest declared; study funded by an academic institution without industry involvement.
Funders
Authors declare no competing interests. The study appears to be independently conducted with academic funding.
Key takeaways
- 01
After 12 weeks, the whey group lost about 2.2 kg more body weight and 1.5 kg more fat, while gaining 0.5 kg of muscle.
- 02
The soy group also lost weight and fat but did not gain muscle.
- 03
Yes, the differences between whey and soy are meaningful for weight management.
- 04
Whey protein appears to be more effective for both fat loss and muscle gain.
Surprising findings
- Soy protein did not increase lean muscle mass, while whey protein did.Many people believe soy can help build muscle, but this study found no significant muscle gain with soy (P=0.37), only fat loss.
- The study had published corrections/errata, which may affect confidence in the results.Readers often trust published studies at face value, but this one has known errors that require attention.
- Even the soy group lost weight and fat, just not as much as whey.It's not that soy is ineffective – it's just that whey is superior. Both proteins helped, but whey gave extra benefits.
Practical takeaways
If you're an overweight man, try drinking a whey protein shake (about 65g) 30 minutes before your largest meal to reduce appetite and boost fat loss while preserving or gaining muscle.
This dosage is high; a more practical approach is 25-50g whey protein before lunch. Also, the study only included men – effects in women may differ.
medium confidenceIf you prefer plant-based proteins, soy can still help with weight loss, but don't expect it to build muscle on its own.
Soy protein in this study did not increase lean muscle. Combining soy with resistance training may yield different results.
medium confidenceUse protein preloads as part of a structured weight loss plan, not as a magic bullet. Consistency over 12 weeks produced the results.
The study was free-living, so adherence was high (94-95%). Real-world compliance may vary.
high confidenceWhy this study matters
Whey vs Soy: The Weight Loss Showdown
In a 12-week trial, men who drank 65g of whey protein before lunch lost significantly more weight (2.2 kg extra), more fat (1.5 kg extra), and gained 0.5 kg of muscle, while the soy group lost weight and fat but no muscle gain.
Many people assume all proteins are equal for weight loss, but this study shows whey has unique advantages for body composition.
Appetite Control: Whey Wins Again
Both groups felt less hungry and ate fewer total calories, but whey caused a significantly greater reduction in appetite (P=0.032) and calorie intake (P=0.045) compared to soy.
Knowing which protein type keeps you fuller longer can help people make smarter meal choices.
Timing Matters: The 30-Minute Preload Strategy
Participants consumed the protein 30 minutes before their largest meal (lunch). Both groups reduced calorie intake at that meal, but whey had a stronger effect.
This is an easy, actionable strategy – drink a protein shake half an hour before a big meal to naturally eat less.
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 whether drinking a protein shake before lunch helps overweight men eat less and lose weight. They compared whey protein (from milk) and soy protein. Men who had whey protein before lunch felt less hungry, ate fewer calories, lost more weight and fat, and gained more muscle than those who had soy protein.
Research results
After 12 weeks, the whey group lost about 2.2 kg more body weight and 1.5 kg more fat, while gaining 0.5 kg of muscle. The soy group also lost weight and fat but did not gain muscle.
What this means - more context
Yes, the differences between whey and soy are meaningful for weight management. Whey protein appears to be more effective for both fat loss and muscle gain.
To compare the effects of whey protein concentrate vs soy protein isolate preloads consumed 30 minutes before lunch on appetite, calorie intake, anthropometry, and body composition in overweight and obese men.
In a 12-week randomized double-blind trial, 45 overweight/obese men consumed either 65g whey protein concentrate or 60g soy protein isolate preloads before lunch. Both groups reduced appetite and calorie intake, but whey protein led to significantly greater reductions in body weight, BMI, waist circumference, body fat mass, and increased lean muscle mass compared to soy. The study has published corrections; readers should consult the erratum.
Methods Used
Randomized, double-blind, parallel-group trial. 45 overweight/obese men (BMI 25-40 kg/m²) were randomly assigned to whey (n=26) or soy (n=19) groups. They consumed 65g WPC or 60g SPI dissolved in 500mL water 30 minutes before ad libitum lunch for 12 weeks. Appetite, calorie intake, anthropometry, and body composition were measured biweekly and at baseline/end.
Main Finding
Whey protein preloads significantly reduced appetite (P=0.032), calorie intake (P=0.045), body weight (P=0.008), BMI (P=0.006), waist circumference, body fat mass, and increased lean muscle mass compared to soy protein preloads over 12 weeks.
Confidence Level
Moderate - well-designed RCT but small sample size (45 men) and only male participants, plus there are corrections/errata to review.
Study Flags
Red Flags
- •Small sample size (45 men)
- •Only male participants
- •Study has published corrections/errata
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
Soy protein did not increase lean muscle mass, while whey protein did.
Many people believe soy can help build muscle, but this study found no significant muscle gain with soy (P=0.37), only fat loss.
Practical Takeaways
If you're an overweight man, try drinking a whey protein shake (about 65g) 30 minutes before your largest meal to reduce appetite and boost fat loss while preserving or gaining muscle.
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 554 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study gave one group of men whey protein and another group soy protein before lunch for 12 weeks. They found that the whey group felt less hungry and lost more weight than the soy group. But because only 45 men were in the study and some dropped out, we can't say for sure that whey works the same for everyone.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Randomized, double-blind, controlled design minimizes bias.
- Clear intervention (whey vs soy) and outcome measures (appetite, calorie intake, anthropometry, body composition).
- 12-week duration allows for medium-term effects.
Weaknesses
- Small sample size (n=45) reduces statistical power and precision.
- Unbalanced group sizes after dropout (WPC:26, SPI:19) may affect comparability.
- Dropout occurred only in the SPI group (7 participants), possibly introducing attrition bias.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at whether drinking a protein shake before lunch helps overweight men eat less and lose weight. They compared whey protein (from milk) and soy protein. Men who had whey protein before lunch felt less hungry, ate fewer calories, lost more weight and fat, and gained more muscle than those who had soy protein.
Research results
After 12 weeks, the whey group lost about 2.2 kg more body weight and 1.5 kg more fat, while gaining 0.5 kg of muscle. The soy group also lost weight and fat but did not gain muscle.
What this means - more context
Yes, the differences between whey and soy are meaningful for weight management. Whey protein appears to be more effective for both fat loss and muscle gain.
To compare the effects of whey protein concentrate vs soy protein isolate preloads consumed 30 minutes before lunch on appetite, calorie intake, anthropometry, and body composition in overweight and obese men.
In a 12-week randomized double-blind trial, 45 overweight/obese men consumed either 65g whey protein concentrate or 60g soy protein isolate preloads before lunch. Both groups reduced appetite and calorie intake, but whey protein led to significantly greater reductions in body weight, BMI, waist circumference, body fat mass, and increased lean muscle mass compared to soy. The study has published corrections; readers should consult the erratum.
Methods Used
Randomized, double-blind, parallel-group trial. 45 overweight/obese men (BMI 25-40 kg/m²) were randomly assigned to whey (n=26) or soy (n=19) groups. They consumed 65g WPC or 60g SPI dissolved in 500mL water 30 minutes before ad libitum lunch for 12 weeks. Appetite, calorie intake, anthropometry, and body composition were measured biweekly and at baseline/end.
Main Finding
Whey protein preloads significantly reduced appetite (P=0.032), calorie intake (P=0.045), body weight (P=0.008), BMI (P=0.006), waist circumference, body fat mass, and increased lean muscle mass compared to soy protein preloads over 12 weeks.
Confidence Level
Moderate - well-designed RCT but small sample size (45 men) and only male participants, plus there are corrections/errata to review.
Study Flags
Red Flags
- •Small sample size (45 men)
- •Only male participants
- •Study has published corrections/errata
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
Soy protein did not increase lean muscle mass, while whey protein did.
Many people believe soy can help build muscle, but this study found no significant muscle gain with soy (P=0.37), only fat loss.
Practical Takeaways
If you're an overweight man, try drinking a whey protein shake (about 65g) 30 minutes before your largest meal to reduce appetite and boost fat loss while preserving or gaining muscle.
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 554 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study gave one group of men whey protein and another group soy protein before lunch for 12 weeks. They found that the whey group felt less hungry and lost more weight than the soy group. But because only 45 men were in the study and some dropped out, we can't say for sure that whey works the same for everyone.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Randomized, double-blind, controlled design minimizes bias.
- Clear intervention (whey vs soy) and outcome measures (appetite, calorie intake, anthropometry, body composition).
- 12-week duration allows for medium-term effects.
Weaknesses
- Small sample size (n=45) reduces statistical power and precision.
- Unbalanced group sizes after dropout (WPC:26, SPI:19) may affect comparability.
- Dropout occurred only in the SPI group (7 participants), possibly introducing attrition bias.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study was well-designed because they randomly split the men into two groups and no one knew which protein they were getting. This helps make sure the results are fair. However, more men dropped out of the soy group, which might have made the results look better for whey. So it's a good study, but not perfect.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
80 / 100
- Randomization+20/20
- Blinding+15/15
- Control group+15/15
- Sample size (n=45)+4.0/20
- Follow-up+10/10
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- 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 554 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. The RCT design allows for causal inference, but limitations include small sample size (n=45), unbalanced groups after dropout (WPC:26 vs SPI:19), dropout only in the SPI group, single sex (men), and free-living conditions with potential confounding. Therefore, causation is supported but with moderate confidence.
No Conflicts
No conflicts of interest identified
No conflicts of interest declared; study funded by an academic institution without industry involvement.
Funders
Authors declare no competing interests. The study appears to be independently conducted with academic funding.
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 Thomas DeLauer cite this study, drawing 1 claim from it.
- Contradicted
Evidence contradicts this claim.
Evidence
Authored by
5 researchersIf this is your work, this is how we attribute it on Fit Body Science. Atefeh Tahavorgar is listed as the lead author.