Caffeine
Caffeine is a naturally occurring stimulant found in coffee beans, tea leaves, cacao, and guarana. It is the most widely consumed psychoactive compound in the world, valued for its ability to enhance mental alertness, physical performance, and metabolic rate.
Research Evidence
Supports appetite regulation and may reduce caloric intake
ModerateEnhances alertness and reduces perceived fatigue
StrongReduces morning sleep inertia and grogginess
ModerateImproves aerobic and anaerobic exercise performance
StrongIncreases resting metabolic rate by approximately 3-11%
StrongExpert Evidence
309 references from 6 experts
“For me it's water and some form of caffeine.”
Essentials: Optimize Your Exercise Program with Science-Based Tools | Jeff Cavaliere
32:53140 references in 83 episodes from 2021–2026
Safety & Cautions
Side Effects
- Insomnia and disrupted sleep
- Anxiety and jitteriness
- Increased heart rate
- Digestive upset
- Tolerance and withdrawal headaches
Caffeine is generally well-tolerated at moderate doses (up to ~400 mg/day for most adults), but individual sensitivity varies widely. High intake may negatively affect bone health over time, and children, pregnant women, and those with anxiety disorders should limit consumption.
Pairs Well With
Price Comparison
From $0.04/ct
B
BulkSupplements
4.4
•500 ct$0.04/ct
$21.96 total
N
NutricostBest Value
4.5
•500 ct$0.04/ct
$18.95 total
P
ProLab
4.5
•200 ct$0.06/ct
$11.99 total