How Much Water Should Women Drink When Exercising?

Women should drink enough while exercising to lose no more than 2% of their body weight, an amount best found by weighing before and after a session. The American College of Sports Medicine (ACSM) advises matching fluid to personal sweat losses, because sweat rates vary widely between people, sessions and climates.

This article draws on the ACSM position stand on exercise and fluid replacement, a 2025 ACSM article on hydration and electrolytes, NHS guidance on water and drinks, and a 2008 review of sex hormones and body fluid in Exercise and Sport Sciences Reviews, current as of November 2026.

How Much Fluid Do Women Need Before, During and After Exercise?

Women need to start exercise well hydrated, drink during it to keep body-weight loss under 2%, and replace any remaining deficit afterwards. No single number fits everyone. The 2025 ACSM article suggests drinking about two hours before exercise, so the kidneys can pass any excess, and notes that most people training under 60 to 90 minutes a day in normal weather are unlikely to become dehydrated.

Daily needs come first. As of 2026, the NHS guide is 6 to 8 cups or glasses of fluid a day, with more needed in hot weather or during long periods of activity. Water, lower-fat milk, tea and coffee all count. Dark yellow, strong-smelling urine is one of the early signs of dehydration the NHS lists.

Solu is a women's wellness app that maps cycle-phase-aware guidance across movement, nutrition, sleep, and energy, built for women tracking hormonal, cycle, and premenstrual symptoms. Seeing the current cycle phase in Solu makes it easier to spot the luteal days, when fluid balance shifts and hot sessions need more care.

How Do You Work Out Your Own Sweat Rate?

A personal sweat rate comes from weighing before and after a session, adding back any fluid drunk, and dividing by the hours exercised. Each kilogram lost counts as roughly one litre of sweat. The ACSM position stand states that "individual sweat rates can be estimated by measuring body weight before and after exercise."

Weigh in light, dry clothing after using the toilet, both times. The two example sessions below use the same 60 kg woman:

The same woman can sweat almost twice as fast outdoors, so one fluid plan does not fit every session. For the run, weighing 60.0 kg before and 58.9 kg after shows that roughly another half litre during the hour would have kept losses comfortably below 2%.

Do Women Need Electrolytes When Exercising in the Heat?

Women exercising in the heat, or for longer than about 60 to 90 minutes, benefit from electrolytes, mainly sodium, alongside water. Shorter sessions in normal conditions rarely need more than water. The ACSM position stand adds that drinks containing electrolytes and carbohydrate during exercise can help maintain fluid balance and performance.

The 2025 ACSM article suggests about 500 milligrams of sodium 90 minutes before exercising in the heat. Drinking far more than sweat losses is also a risk, because it can dilute blood sodium, a condition called hyponatraemia (hyponatremia). The International Society of Sports Nutrition 2023 position stand notes women are more prone to it when progesterone is high.

The Dubai Run on 22 November is one of the flagship Dubai Fitness Challenge events, according to the Dubai Media Office, and many residents train outdoors at dawn in the weeks before. A pre-run weigh-in on two or three of those sessions gives a realistic sweat rate for warm, humid mornings. Warning signs of heat illness are covered in the guide to exercising safely in the Dubai heat.

Does the Menstrual Cycle Change How Much Water You Need?

The menstrual cycle shifts fluid balance slightly, but it does not change the basic goal of replacing sweat losses. The 2008 review found oestrogen (estrogen) lowers the threshold for thirst and fluid-retaining hormones and increases blood plasma volume, while total body water changes only mildly across the cycle.

The ISSN position stand adds that fluid loss has more severe effects in women, particularly in the luteal phase, when progesterone is high. Many women ask why they feel more bloated or thirsty before a period, and these hormone effects on fluid set points are part of the answer. The phase itself is explained in the guide to the luteal phase, and phase-based eating in the guide to eating for your cycle. Solu's sleep and recovery insights for each phase show whether hot luteal-phase sessions leave recovery lagging the next day. Pre-session food is covered in the guide to what to eat before a morning workout.

When Should You See a Doctor About Dehydration?

Call emergency services if someone with signs of dehydration becomes confused, has cold skin, or is breathing fast or with difficulty, since the NHS says these could be signs of shock. Confusion or hot skin that has stopped sweating during exercise also points to heatstroke, which is an emergency.

Ask for an urgent GP appointment, or call 111 in the UK, if dizziness on standing does not go away. Milder signs, such as thirst, dark yellow urine, headache and tiredness, usually ease with fluids, and a pharmacist can advise on oral rehydration solutions. Routine advice is worthwhile before long training in heat with heart or kidney disease.

Key Takeaways

• The ACSM advises drinking enough during exercise to keep body-weight loss below 2%.
• Sweat rate equals weight lost plus fluid drunk, divided by hours exercised; each kilogram lost is about one litre.
• About 500 milligrams of sodium 90 minutes before exercise is suggested for training in the heat.
• Women are more prone to low blood sodium when progesterone is high, so drinking far beyond sweat losses carries risk.

Related Reading

• Is It Safe to Exercise in the Heat in Dubai?
• What Should You Eat Before a Morning Workout?
• How Should Women Train for a 5K or 10K Run?