On the topic of hydration, some well-meaning soul invariably brings up that drinking caffeinated beverages contributes to dehydration because it is a diuretic. Or in other words, you can't be properly hydrated if you are looking to get hydration from caffeinated drinks. I've read that caffeine doesn't start acting like a diuretic until you consume a certain amount, so I asked Gemini about this, and here's the response:

The diuretic effect of caffeine is mild and depends on several factors, including:

Habitual intake: People who regularly consume caffeine tend to develop a tolerance to its diuretic effect.
Hydration status: Dehydration can make caffeine's diuretic effect more pronounced.
Beverage choice: Coffee and tea contain other substances that may counteract caffeine's diuretic effect.

Studies suggest that a dose exceeding 250mg of caffeine can have a diuretic effect, although some studies show conflicting results around this amount. For reference, a cup of brewed coffee typically contains around 80-100mg of caffeine.

However, it's important to remember that most caffeinated beverages also contain fluids. So, as long as you're not consuming excessive amounts of caffeine and staying hydrated, the diuretic effect is unlikely to be significant.

Here's a more detailed breakdown of caffeine content in common beverages:

Cup of brewed coffee (8oz): 80-100mg
Cup of black tea (8oz): 47mg
Can of soda (12oz): 30-40mg
Shot of espresso (1oz): 64mg
Energy drink (16oz): 300mg (can vary widely)