Supplement Log

A stimulant that blocks adenosine receptors — the molecule that builds up through the day and makes you sleepy. It does not give energy; it mutes the signal for a while.

Improves exercise performance by 2-4% across endurance, strength and power, confirmed by an umbrella review of 21 meta-analyses. One of the few here that genuinely and clearly works.

Raises cortisol transiently, which fades as tolerance develops, and briefly lowers insulin sensitivity after a dose.

Raises energy expenditure by 4-6% acutely, but tolerance and compensatory eating cancel it, leaving nearly nothing long term. The real benefit is training harder, not burning fat directly.

This is caffeines clearest effect, and it is negative: 400 mg taken six hours before bed still cuts over an hour of measured sleep, and the drinkers did not notice. If you want to fix your sleep, this is the first thing to address.

Alertness, focus and performance. Whole coffee carries other beneficial compounds that a caffeine tablet does not.