How Does Your Body Process Alcohol?
When you drink an alcoholic beverage, your body begins processing it almost immediately. Understanding alcohol metabolism helps explain why BAC rises and falls — and why some people are affected differently than others.
Alcohol metabolism occurs in three main phases: absorption, distribution, and elimination. Each phase affects how quickly your blood alcohol content changes.
The Three Phases of Alcohol Metabolism
Metabolism Rate
The average person metabolizes alcohol at a rate of approximately 0.015% BAC per hour, which is roughly equivalent to one standard drink per hour. This rate is relatively constant and is not significantly affected by:
- Coffee or energy drinks (caffeine does not speed metabolism)
- Cold showers or fresh air
- Exercise or physical activity
- Eating food after drinking (though food before/during can slow absorption)
Average elimination rate: ~0.015% BAC per hour ≈ 1 standard drink/hour
Individual metabolism rates can vary from 0.010% to 0.020% per hour depending on genetics, liver health, and regular drinking habits. Use our BAC calculator to estimate when your BAC might return to zero.
Why Some People Are Affected More Than Others
Several biological factors explain why the same number of drinks can affect people very differently:
Body Composition
People with more body fat and less water will have a higher BAC. Alcohol does not distribute into fat tissue, so it concentrates in a smaller volume of body water.
Genetics
Genetic variations in ADH and ALDH enzymes affect how quickly alcohol is processed. Some populations (particularly East Asian descent) may have enzyme variants that cause rapid acetaldehyde buildup, leading to flushing and nausea.
Tolerance
Regular drinkers may develop functional tolerance (feeling less impaired), but their BAC is not lower. Tolerance masks impairment — it does not reduce it.