Why Are Nearly Half of Women Dehydrated Before They Work Out?

Nearly half of women show up to a workout already dehydrated, and more than half don't eat enough carbs to actually fuel it. That's not a guess, it's what Gatorade's own research arm found when it finally sat down and studied women's bodies instead of assuming they work like men's. The study, called "Body of Science," came out this week, and if you've ever finished a workout feeling wrecked instead of good, it might explain why.

What did the Gatorade study actually find?

The Gatorade Sports Science Institute tracked more than 500 women across basketball, soccer, and ice hockey and found some genuinely uncomfortable numbers. Forty-three percent arrived at their workouts already dehydrated, before they'd even started. Fifty-seven percent under-fueled with carbohydrates during exercise, and half of that group ate none at all. On sodium, women were replacing only about 20 percent of what they lost through sweat, when the science says they should be closer to 50 percent. Basketball players lost the most sodium of any sport measured.

Dr. Kimberly Stein, the senior principal scientist who led the study, put it plainly: "These aren't small gaps between what women's bodies need and how they're fueling. They're the difference between feeling your best and unknowingly falling short." WNBA star A'ja Wilson, who's spent her career training inside a system built for men, said understanding what female bodies actually need "shouldn't be a luxury."

Here's the part that explains all of it: only about 6 percent of global sports science research focuses exclusively on women. For decades, hydration and fueling guidelines were built on studies of men and applied to women by assumption, not evidence. Gatorade's own numbers back up how much that's cost people: 65 million women say dehydration affects their mood and focus, nearly a third of women skip sports during their period, and 80 percent of them have never gotten any specific advice about how to fuel around it. This is the same blind spot that shows up when women are left out of research on creatine and mental health or any other field where "the general population" quietly meant "men."

Why this matters for you

If you've ever felt shaky, foggy, or wiped out after a workout and figured you just needed to push through it, this study is basically telling you: maybe you needed water and carbs, not willpower. Women's bodies change how they handle fluid and fuel across the menstrual cycle, and most of us were never taught that, because the research to teach it barely existed until now. That's not a personal failing. It's a 40-year data gap you inherited.

This isn't only about elite athletes. If you walk, lift, run, do a class, or chase a toddler around a park, the same logic applies: your body's needs are real and specific, and "just drink water when you're thirsty" isn't always enough, especially in heat or during longer sessions. Fueling well isn't about eating more in general, it's about eating with intention around the moments your body is actually working hard, the same idea behind the protein swap that changes how your meals actually fuel you. And if you've noticed your energy tanking for reasons that don't add up, it's worth remembering how much something like lost sleep can quietly wreck your body's fueling and weight signals too. Your body is talking. Most of us were just never given the manual to translate it.

One thing to try today

Before your next workout, drink about 16 ounces of water in the hour beforehand instead of waiting until you're thirsty, and if you're going longer than 45 minutes, bring something with actual carbs, a banana, dates, a granola bar, not just water. That's it. Small, specific, and it's literally what the research says closes the gap.

Quote to sit with:

"Just that whole attitude of being strong and powerful; that's something I can get behind." — Serena Williams

💌 Sarah