As a chemical, caffeine increases production of urine, which means caffeine is a diuretic. But most research suggests that the fluid in caffeinated drinks balances the diuretic effect of typical caffeine levels. High doses of caffeine taken all at once may increase the amount of urine the body makes.
Coffee is unlikely to dehydrate you
Researchers observed that drinking the higher caffeine coffee had a short-term diuretic effect, whereas the lower caffeine coffee and water were both hydrating ( 15 ). In addition, other studies show that moderate coffee intake is as hydrating as drinking water ( 16 ).
The answer is yes, coffee does count toward your daily water intake. However, drinking huge amounts of caffeine can be dehydrating. That's because it may increase urination that can result in a higher risk of dehydration. While coffee is hydrating, it lacks electrolytes our body needs for complete hydration.
Research shows that milk is one of the best beverages for hydration, even better than water or sports drinks. Researchers credit milk's natural electrolytes, carbohydrates, and protein for its effectiveness.
What counts towards your fluid intake? Non-alcoholic fluids, including tea, coffee and fruit juice, all count towards your fluid intake.
Water is your best bet for everyday hydration, since it is free of sugar, calories, and caffeine. All of your daily food and beverages contribute to your daily fluid needs.
Drink an ORS Before Bed
Instead of drinking a glass of water, drink an oral rehydration solution like DripDrop ORS, which also contains electrolytes that are essential for hydration. Try to drink the ORS an hour or two before bed so you don't wake up in the middle of the night to use the restroom.
In general, however, it usually takes about two hours for your body to rehydrate fully after drinking a significant amount of water. As for how you should rehydrate, water is the best choice. Sports drinks, such as Gatorade, can be helpful for athletes who need to replenish electrolytes.
So, what if you drink loads of water each day but are still feeling thirsty and dehydrated? It can be a sign that something else is going on. Factors like your medication, how much you sweat and if you're sick can affect your levels of hydration.
Plain water is the best way to hydrate, no second guessing necessary.
Takeaway. After you drink water, it doesn't take long at all for your body to absorb it. Unlike foods, water can be “digested” in as little as 5 minutes. Excess water leaves your body through urination and feces but is also excreted by sweating.
Signs of dehydration include: Headache, delirium, confusion. Tiredness (fatigue). Dizziness, weakness, light-headedness.
And drinking H2O is an effective way for most people to stay hydrated. The National Academy of Medicine recommends that adult women and men drink at least 91 and 125 ounces of water a day, respectively. (For context, one gallon is 128 fluid ounces.)
Overhydrating can result in what's called hyponatremia, where you retain water but flush out necessary electrolytes like sodium and potassium. This causes cells all over the body to swell and can lead to nausea, vomiting, dizziness and, in rare cases, even death.
In fact, water may not even crack the top five of the most hydrating drinks out there. According to a study from Scotland's St. Andrew's University, milk, Pedialyte and soda top the list of most hydrating beverages.