According to wikipedia:
- Contrary to popular belief, caffeine does not act as a diuretic when consumed in moderation, and does not lead to dehydration or to a water-electrolyte imbalance; current evidence suggests that caffeinated beverages contribute to the body's daily fluid requirements no differently than pure water does.[25][26][27][28]
Furthermore according to coffeescience:
- He concluded, “We found no evidence of acute or chronic dehydration in C3 or C6 during 11 days of controlled caffeine consumption. Our findings question the widely accepted notion that caffeine acts chronically as a diuretic.“
- The mild diuretic effect in coffee, tea and soda stems from their active agents, classified as methylxanthines. Dr. Armstrong explained, “The caffeine in coffee, tea, and soft drinks is 1,3,7-trimethylxanthine. Tea contains theophylline – 1,3-dimethylxanthine. Theobromine is found in tea, chocolate and cocoa as 3,7-dimethylxanthine. All three compounds are central nervous system and cardiac stimulants, as well as mild diuretics in some situations.
Less authoritatively from caffeine-addiction-and-its-diuretic-effect-on-the-body
- If you consume more than two cups of coffee each day then a multi-vitamin should be taken once daily to help replenish was is lost by the diuretic effects of caffeine in the body.
However, continuing with wikipedia
- Coffee is also a powerful stimulant for peristalsis and is sometimes considered to prevent constipation. However, coffee can also cause excessively loose bowel movements. The stimulative effect of coffee consumption on the colon is found in both caffeinated and decaffeinated coffee.[23][24]
I suggest that perhaps the diuretic effect is caused by some activity or product associated with coffee drinking, for example Herbal aquaretics Wikipedia
- Herbal aquaretics include adonis, agrimony, bearberry, buchu, dandelion, heartsease, hydrangea, lady's mantle, larch, and sassafras. These increase blood flow to the kidneys
$Thanks for the idea Michelle
