Let's now turn to some studies that looked directly at testosterone levels following acute alcohol administration. In adult males, 1.3g/kg of ethanol (about 10 drinks for a 200 lb person), caused a significant decrease vs. basal levels at the 60 minute mark. Differences for the next two hours were not significant, though the researches did not utilize a control group, so the natural morning rise in testosterone could have masked any effects ( 38 ). 1.5g/kg lowered levels by an average of 23% over a 24 hour period ( 28 ). 1.75g/kg lowered levels by 27% and 16% at 12 and 24 hours, respectively ( 34 ). Adolescent males admitted to the hospital for alcohol intoxication were found to have 21% lower testosterone levels than controls (36).Originally Posted by someone from the closed pot thread - damn people need to UTFSE!!
A couple of studies have looked at alcohol and exercise. 1.5g/kg depressed testosterone by more than 20% by 1 hour and was still depressed by the same margin at hour 10 ( 37 ). Interestingly, when the same ethanol dose was preceded by an exercise session, the suppressive effect continued for 22 hours -- and when exercise was performed during a hangover, significant suppression ( 21-32% ) vs. ethanol alone continued for 26 hours. Compared to control, both ethanol groups had significantly lower testosterone levels for 42 hours - this is almost 2 full days. A much smaller intake (.83g/kg) did not result in a significant decrease ( 35 ).
All of this is at what are fairly moderate doses. Let's take a look at binge drinking doses.
Probably for ethical reasons, doses equating to 20+ drinks have not been studied in humans, so we must settle for rat data, but considering the effects at lower doses seem quite similar, these studies are likely quite relevant -- and could actually underestimate the effect, since, as we mentioned, these doses resulted in much lower blood alcohol levels in rats than humans.
3g/kg caused massive suppression of testosterone ( 67 ). Between hours 1.5 and 96 (yes, 4 days later), testosterone was reduced between 50-75% and, even a full week later, it was still down 40%. By week two, it was finally back to control level. 3g/kg also reduced HCG stimulated testosterone secretion by 75% ( 66 ). In male macaque monkeys, 2.5 and 3.5g/kg reduced testosterone levels by 63 and 70%, respectively ( 68 )
One study in adolescent rats found that testosterone levels doubled for the first 3 of weeks of ethanol ingestion ( 69 ) -- however, this was with an intake equal to 90 drinks per day for a 200 lb person. If anyone tries this, please report back with your results.
On the other hand, levels below 1g/kg seem to have no deleritous effects ( 35, 70 ).