La Croix is lovely, but bubbly drinks shouldn’t be your choice for hydration, according to Bonci: The carbonation can cause gas and bloating, neither of which are great for an exercise routine. “Carbonation can also delay fluid getting to your muscles,” she says. Skip the sparkling water and even the kombucha, which can be fizzy.
There are a lot of sugary liquids masquerading as energy drinks, claiming to replenish electrolytes and help you work out harder. The problem, Bonci says, is that overhydrating can bring too much fluid into your stomach with not enough exiting, which can be detrimental to your workout. She recommends looking for a drink that has between 14 and 15 grams of carbs per 8 ounces and chugging only a single bottle. If your workout is less than an hour, you can drink water during exercise itself.
Although studies suggest that caffeine can boost your performance and reaction times, that’s only true for moderate levels (around 200 milligrams). Because the average 12-ounce cup of coffee is easily 250 to 300 milligrams, warns Bonci, you’re better off limiting yourself to a half cup. And the same rule applies to energy gels, goos, and bars spiked with caffeine, so read labels carefully.