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Head-to-head evidence comparison — which supplement is right for you?
Caffeine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
28 of 34 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (2)
Outcomes where both Caffeine and TMG have evidence — compare verdict strength side-by-side.
100-200mg
Morning, 30-60 minutes before exercise
Pill/capsule for precise dosing
2.5-6g betaine/TMG daily (performance studies commonly use ~2.5g; methylation/homocysteine use up to 6g)
with-meals
Betaine anhydrous (TMG)
15-45 minutes
30-60 minutes
30-60 minutes
30-60 minutes
2-6 weeks
4-8 weeks
4-8 weeks
Throughout use
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).
Effects of Betaine Supplementation on Muscle Strength and Power: A Systematic Review.
Journal of strength and conditioning research (2017) · Systematic review
Some improvement in strength/power endpoints
Effects of chronic betaine supplementation on exercise performance: Systematic review and meta-analysis.
Journal of sports sciences (2024) · Meta analysis
Modest benefit on some performance measures
Betaine supplementation fails to improve body composition: a systematic review and meta-analysis.
The British journal of nutrition (2022) · Meta analysis
No significant change in body fat or lean mass
Based on multiple meta-analyses showing 3-6mg/kg optimal dosing. Performance benefits plateau around 200-300mg with increased jitteriness at higher doses.
AI-estimated from published studies. Interpret as directional guidance.
Caffeine has a higher evidence score (9.5/10 vs 5.8/10) and wins in 2 of 3 categories.
For improve endurance, Caffeine has a higher relevance score (85 vs 48).
No known interactions between Caffeine and TMG have been documented in our database. However, always consult a healthcare provider before combining supplements.