What factors affect blood alcohol concentration?

• A. Time of day.
• B. Rate of consumption, gender, body size, and amount of food in the stomach.
• C. The weather.
• D. Genetic factors alone.

Answer: (B)

Blood alcohol concentration reflects how much alcohol is in the bloodstream at a given moment, which is shaped most directly by how you drink, your body, and whether you’ve eaten. If you drink more quickly, more alcohol enters the blood before the liver can metabolize it, so the peak BAC is higher. Body size matters because alcohol distributes in body water; a larger person usually has more water to dilute the alcohol, resulting in a lower BAC for the same amount of drink, while a smaller person has less dilution and a higher BAC. Gender influences BAC because, on average, women have less body water and different enzyme activity, which can lead to higher BAC for the same dose. Having food in the stomach slows absorption by delaying gastric emptying, so peak BAC tends to be lower and rise more slowly when you’ve eaten.

Time of day or weather don’t directly change how alcohol is absorbed or metabolized, and while genetics can affect metabolism, it isn’t the sole determinant. The overall BAC outcome comes from these interacting factors: how fast you drink, your body size and sex, and whether you’ve eaten.