A lot of people who have chugged a Starbucks “venti” before taking a long bus or train ride to work will probably tell you that caffeine is definitely a diuretic. The science is actually very mixed, however.
Thus far, the results have seemed to indicate that if it is a diuretic, either the effects are highly individualized or it only exerts a strong effect in people who aren’t regularly consuming it. Under most circumstances, caffeine intake hasn’t actually been shown to cause any excess urination or dehydration. 
A new study may have found an exception, however — at least for women. The study shows that a fairly high dose of caffeine prior to exercise consistently acted as a mild diuretic. The control group of men did not experience the same effect.
Hold Your Water
The study was a literature review that incorporated only previous studies that used healthy adults and had sufficient data on the effect size (the exact measured difference) of caffeine ingestion on urine volume. 16 studies made the final cut.
The median dose in these studies was 300mg, which is a fairly high dose even for supplementation. For the sake of comparison, that’s equivalent to the content of about three and 1/3 cups of coffee. In addition to controlling for gender differences, non-exercising control groups were also incorporated. The end result was a small but significant difference in the urine volume of the exercising women.
What It Means
Usually one study isn’t anywhere near conclusive, but this one carries a little more weight than usual since it was a comprehensive literature review. We still can’t say for certain that caffeine will exert a diuretic effect on all women when they exercise, but a study or two directly testing this hypothesis could easily validate it.
Let’s say these results do hold true for all women. There is one little hink here in that the median dose of caffeine was definitely on the high side at 300mg.
Workout supplements do sometimes go this high, but it’s relatively uncommon as users who don’t have a high caffeine tolerance may get the jitters and an overall unpleasant feeling from a dose that high. Pyroxamine, for example, has only 100mg per serving — just over a cup of coffee’s worth, a fairly proven and standard dose for good energy without “stim jitters.”
That’s not a completely unsafe dose of caffeine, however, just one that can cause unpleasant side effects in those that are more sensitive to it. The extra 100ml (roughly) of water loss per exercising female participant also didn’t enter the unsafe range. A concern about diuretics is improper use of them, leading to too much water being flushed too quickly and severe dehydration, or even organ failure in extreme cases.
So for the fit and active woman who has a temporary need to cut water weight, a high dose of caffeine is looking promising as a simple and safe way to do it. Of course, water weight loss is not permanent weight loss, but sometimes you need to make a weigh-in (or just look good in a dress for a night). When combining with your Pyroxamine, added supplementation will be needed, but basic caffeine pills can be had from dollar stores.
Pyroxamine For Lasting Fat Loss
Cutting water weight has its time and place, but what you really want is to take stored fat off and keep it from coming back. With Pyroxamine you get potent lipolysis and thermogenesis from caralluma fimbriata, olive leaf, bacopa monniera extract, Grains of Paradise and evodia rutaecarpa. All tested and proven, and combined with the High Energy Matrix, give you the long-term weight control results you’re looking for.