View Full Version : So is coffee a diuretic or no?

05-12-2019, 08:57 AM
So is coffee a diuretic? I have heard that recently the fda has reversed its classification from a diuretic to no longer being considered one. I have yet to find anything significantly confirming on either end at the FDA's website. So can you guys help me out, what is the official consideration?

05-12-2019, 09:14 AM
You'd have to have a good reason to argue with the FDA.

The body generally works harder to get water out of foods and drinks when you are more dehydrated.

05-12-2019, 09:50 AM
Why does it matter what the FDA classified coffee as?

Caffeine’s diuretic properties are shaky at best, and highly user-tolerance dependent.

05-13-2019, 04:13 AM
not sure but it's great for suppressing hunger

05-13-2019, 02:40 PM
I find I go to the toilet a lot more frequently when I drink lots of coffee and diet coke compared to just plain water

05-13-2019, 03:14 PM
More of a poopuretic IMO

x-ray vision
05-13-2019, 04:50 PM
"[T]he truth of the matter is, a small increase in urine output has little to do with dehydrating the body," Armstrong told Live Science.

He added that any increase in fluid input will lead to an increase in urine output. "If you drink a liter of water, [urination] will increase," Armstrong said. "Doesn't mean you shouldn't drink water."

In 2005, Armstrong and a team of researchers set out to put the myth to rest. They controlled the diets of 59 healthy males for 11 days, supplementing their daily consumption with body-mass-appropriate doses of caffeine, administered twice a day via capsule. Throughout the study, the researchers employed 20 different hydration biomarkers, such as urine volume and fluid-electrolyte balance, to assess dehydration.

While previous studies had investigated the effects of caffeine over short periods of time, Armstrong's research was the first to evaluate caffeine consumption for a continuous period longer than 24 hours.

The study found that the evaluated hydration indicators, including urine volume, were similar for all of the treatment groups. This finding demonstrates that caffeine does not have a dehydrating effect when compared to the control group (participants who received a placebo and did not consume any caffeine). The scientists also found that a higher dose of caffeine was no more likely to dehydrate a person than smaller doses were.

It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance. The aim of this study was to directly compare the effects of coffee consumption against water ingestion across a range of validated hydration assessment techniques. In a counterbalanced cross-over design, 50 male coffee drinkers (habitually consuming 3–6 cups per day) participated in two trials, each lasting three consecutive days. In addition to controlled physical activity, food and fluid intake, participants consumed either 4×200 mL of coffee containing 4 mg/kg caffeine (C) or water (W). Total body water (TBW) was calculated pre- and post-trial via ingestion of Deuterium Oxide. Urinary and haematological hydration markers were recorded daily in addition to nude body mass measurement (BM). Plasma was analysed for caffeine to confirm compliance. There were no significant changes in TBW from beginning to end of either trial and no differences between trials (51.5±1.4 vs. 51.4±1.3 kg, for C and W, respectively). No differences were observed between trials across any haematological markers or in 24 h urine volume (2409±660 vs. 2428±669 mL, for C and W, respectively), USG, osmolality or creatinine. Mean urinary Na+ excretion was higher in C than W (p = 0.02). No significant differences in BM were found between conditions, although a small progressive daily fall was observed within both trials (0.4±0.5 kg; p<0.05). Our data show that there were no significant differences across a wide range of haematological and urinary markers of hydration status between trials. These data suggest that coffee, when consumed in moderation by caffeine habituated males provides similar hydrating qualities to water.


With acknowledgement of the study's limitations, results suggest that coffee did not result in dehydration when provided in a moderate dose of 4 mg/kg BW caffeine in four cups per day. Thus, these data suggest that coffee, when consumed in moderation by caffeine habituated males contributes to daily fluid requirement and does not pose a detrimental effect to fluid balance. The advice provided in the public health domain regarding coffee intake and hydration status should therefore be updated to reflect these findings.