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Head-to-head evidence comparison — which supplement is right for you?
Caffeine vs Whey Protein: Whey Protein has the stronger overall evidence (9 vs 9.5/10); they're alternatives for boost daily energy — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Whey Protein wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
29 of 35 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
26 of 30 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Caffeine and Whey Protein have evidence — compare verdict strength side-by-side.
100-200mg
Morning, 30-60 minutes before exercise
Pill/capsule for precise dosing
20-40g per serving
Post-workout (within 2 hours), Morning, Between meals
Whey Protein Isolate
15-45 minutes
30-60 minutes
30-60 minutes
30-60 minutes
4-8 weeks
24-48 hours post-workout
Immediate
Within hours of consumption
Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis
Nutrients (2020) · Meta analysis · n=2020
A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials
Critical reviews in food science and nutrition (2019) · Meta analysis · n=606
Thirteen RCTs with 606 participants were included in the meta-analyses.
Effect of Caffeine and Nitrates Combination on Exercise Performance, Heart Rate and Oxygen Uptake: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=95
The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
Comparative Efficacy of Different Protein Supplements on Muscle Mass, Strength, and Physical Indices of Sarcopenia among Community-Dwelling, Hospitalized or Institutionalized Older Adults Undergoing Resistance Training: A Network Meta-Analysis of Randomized Controlled Trials
Nutrients (2024) · Meta analysis · n=5272
Treatment effects for main outcomes were expressed as standard mean difference (SMD) with 95% confidence interval (CI).
Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis
Nutrients (2023) · Meta analysis · n=637
However, appendicular muscle mass significantly improved in the experimental group compared to the control group.
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength
British Journal of Sports Medicine (2018) · Meta analysis · n=1863
Protein supplementation increases muscle mass gains
Based on multiple meta-analyses showing 3-6mg/kg optimal dosing. Performance benefits plateau around 200-300mg with increased jitteriness at higher doses.
Based on multiple meta-analyses with >3000 participants. Effects require concurrent resistance training. Benefits plateau around 30-40g per serving. Isolate forms may reduce digestive issues.
AI-estimated from published studies. Interpret as directional guidance.
Whey Protein has a higher evidence score (9/10 vs 9.5/10) and wins in 2 of 3 categories.
For boost daily energy, Caffeine has a higher relevance score (98 vs 60).
No known interactions between Caffeine and Whey Protein have been documented in our database. However, always consult a healthcare provider before combining supplements.
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Caffeine, citrulline, beta-alanine, creatine — the ingredients that work, at clinical doses (vs fairy dusting).
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.