Women get around a thousand percent increase in, in testosterone at a 24 hour fast. The only study I can find is that it shows around 24 hours. We just don't have enough studies on it. And we can use fasting in women to increase testosterone. But for the woman who's in her late 30s, early 40s, experiencing low testosterone, it may be she's not motivated to work out anymore or resolve an argument with a loved one.