Hydration for Women: Why Water Is Not Enough

As the temperatures drop across the southern hemisphere, many women unknowingly fall into a hydration deficit. Colder weather tends to blunt the natural thirst response, making it easy to forget to drink enough water. But hydration needs don’t disappear with the summer sun. In fact, dehydration during colder months can be more insidious, as the usual thirst cues are blunted by lower temperatures.

Water is probably the body's most important nutrient, accounting for nearly 70 percent of body weight in a normal adult. For women, hydration becomes even more nuanced due to monthly hormonal fluctuations that affect fluid balance, electrolyte status, and thermoregulation. Unfortunately, the majority of hydration guidelines have been based on male physiology, leaving a significant knowledge gap for women looking to optimize their health and performance.

The general recommendation for daily water intake is 2L per day or 8 glasses, however, for women this is simply not enough. And water alone is not enough—electrolytes play a critical role in maintaining hydration and cellular health. The key electrolytes—sodium, potassium, magnesium, and calcium—work together to maintain blood volume, regulate muscle contractions, balance nerve impulses, and support hormonal signaling.

And here's where it becomes especially relevant for women: fluctuating estrogen and progesterone levels across the menstrual cycle significantly impact fluid retention, electrolyte needs, and thermoregulation. These shifts can change how much water and which minerals you need—day to day, week to week. And dehydration is one of the major players that cause PMS like cramps and mood swings.

How Much Water Should Women Consume?

Water plays a role in nearly every physiological function—from thermoregulation and cardiovascular health to digestion, nutrient transport, and detoxification (Popkin et al., 2010).

An adjusted guideline for water intake is 35–40 mL per kilogram of body weight every day. This equates to, for example: 2.17-2.48L for a 62kg woman.

However, fluid needs also increase with:

• Physical activity

• Environmental conditions (humidity, altitude)

• Caffeine intake

• High protein or high fiber diets

• Menstrual cycle or hormonal fluctuations

Consuming enough water during these phases can:

• Alleviate bloating and water retention

• Reduce the risk of urinary tract infections

• Regulate menstrual flow and duration

• Alleviate menstrual cramps

• Improve energy levels and prevent mood swings

• Prevent constipation

During exercise, sweat losses can range from 0.5 to 2.0 liters per hour depending on intensity, temperature, and clothing. Even in winter, fluid losses can be significant due to the increased respiratory water loss from breathing in dry, cold air.

In hot climates, sweat loss is higher due to the body’s increased need to cool itself.

In cold climates, the thirst response is blunted, and fluid loss still occurs through respiration and urination. You may not feel thirsty, but you’re still losing water. Cold weather does not mean lower hydration needs.

Caffeine is a mild diuretic, which means it increases urine output. While moderate intake (1–3 cups of coffee or tea) doesn’t significantly dehydrate most people, large amounts of caffeine, especially without water, can contribute to fluid loss.

Protein metabolism produces waste byproducts (like urea) that must be filtered through the kidneys, requiring extra water. A high-fibre diet also increases the bulk of food moving through the digestive tract, which requires additional fluid for proper digestion and bowel movements.

Dehydration is a common phenomenon observed in females, especially during the menstrual cycle, a monthly occurrence. Hormonal fluctuations and significant loss of blood and other factors, cause PMS (premenstrual symptoms). The severity of discomfort observed by females during the menstrual phase is primarily caused by dehydration which females ignore. Ideally, the female body tends to produce sufficient fluids during the follicular phase of the menstrual cycle to compensate for the loss of fluids during the menstrual period. However, if a woman doesn't consume adequate water, her body may not be able to make up for the loss. This leads to dehydration and further health problems.

Women should aim to drink an additional:

• 1-2 cups (200-400ml) of water during the late-luteal and menstruation phases (days 22-3), especially if they have heavy or prolonged periods.

• 200-300ml for every 20 minutes of intense exercise.

• 1-2 cups (200-400ml) of water with a high-protein, fiber or caffeine diet.

Electrolytes: More Than Just Salt

Hydration isn’t just about water—it’s also about electrolytes, the electrically charged minerals that regulate nerve function, muscle contractions, fluid balance, and blood pressure. The key players are:

• Sodium (Na⁺): Regulates fluid balance, blood pressure, and nerve impulses

• Potassium (K⁺): Maintains intracellular fluid balance, supports cardiac and muscle function

• Magnesium (Mg²⁺): Involved in over 300 enzymatic reactions, critical for energy production and muscle relaxation

• Calcium (Ca²⁺): Essential for muscle contractions, nerve signaling, and bone health

Electrolyte loss occurs through sweat, urine, and menstruation—and these losses must be replenished through diet or supplementation, especially in physically active women.

Hormonal fluctuations across the menstrual cycle impact fluid retention, thirst, and electrolyte balance. Estrogen and progesterone both influence renal function, thermoregulation, and plasma volume, altering hydration needs.

Exercise, Electrolytes, and Women’s Hydration

When women exercise, especially during the luteal phase, the body works harder to thermoregulate due to the higher baseline body temperature. This leads to:

• Greater sweat loss

• Faster dehydration

• Higher sodium and chloride excretion

• More rapid depletion of magnesium and potassium, which are essential for muscle contraction and recovery

Women may also have lower thirst perception than men during exercise, making it even more critical to proactively hydrate and replace lost minerals (Giersch et al., 2020).

If training regularly, consider adding a balanced electrolyte mix (without added sugars) to your post-workout routine, especially in the luteal phase or during intense sessions. Look for products containing:

• Sodium: ~300–600 mg

• Potassium: ~200–400 mg

• Magnesium: ~100–200 mg

• Calcium: ~100–150 mg

Signs of Dehydration in Cold Weather

Even mild dehydration (1–2% body weight) can impair cognitive function, increase perceived exertion, and reduce exercise performance. In cold weather, dehydration can be harder to detect. Watch for:

• Dry lips or mouth

• Dizziness or headaches

• Muscle cramps

• Fatigue or lethargy

• Dark yellow urine

Hydration isn’t just about avoiding symptoms—it’s about supporting optimal hormonal function, energy metabolism, and muscular recovery.

Hydration & Electrolyte Needs Across the Menstrual Cycle

Early Follicular & Menstruation (Days 1–9):

Women may feel more energetic and have slightly improved fluid balance in the late follicular phase due to estrogen’s positive effect on the renin-angiotensin-aldosterone system (RAAS), which also helps the body retain sodium and manage blood pressure. Estrogen also enhances vasodilation, improving blood flow and thermoregulation. However, due to recent blood loss, women experience water an electrolyte depletion. A balanced intake of magnesium, potassium, sodium, iron, and calcium aids in balancing levels and preventing fatigue. Replenishment through food sources like Himalayan Salt, Olives, Pickles, Bone Broth, Salmon, Sweet Potato, Pumpkin Seeds, Chia Seeds etc. is advised.

• Water Intake: 35-45ml/kg

• Magnesium: 300-400mg

• Potassium: 3000mg

• Calcium: 1000-1200mg

• Sodium: 1500-2000mg

Late Follicular & Ovulation (Day 10-15):

As ovulation approaches, estrogen levels peak, promoting greater water retention by increasing vasopressin sensitivity and renal sodium reabsorption. Potassium and magnesium needs remain stable, while sodium intake can be slightly lower, however, if exercise intensity is intense, electrolyte needs remain high.

• Water Intake: 35-40ml/kg

• Magnesium: 300-350mg

• Potassium: 2600-3000mg

• Calcium: 1000-1200mg

• Sodium: 1200-1500mg

Early Luteal (Days 16-19):

Following ovulation, progesterone begins to rise, accompanied by moderate levels of estrogen. This is the beginning of the luteal phase. Progesterone raises core body temperature and stimulates aldosterone, a hormone that promotes fluid retention. While this sounds beneficial, it can paradoxically lead to blood plasma volume reductions, impairing thermoregulation and endurance during exercise. Aldosterone-driven fluid retention increases sodium excretion through urine, even at rest. Potassium and magnesium requirements also begin to rise, especially if you're training or under stress. Women may notice increased bloating or mild swelling, which may feel like "water retention," yet intracellular hydration and blood volume may actually be compromised.

• Water Intake: 40-45ml/kg

• Magnesium: 300-350mg

• Potassium: 2600-3000mg

• Calcium: 1000-1200mg

• Sodium: 1200-1500mg

Late Luteal (Days 20-28):

Sodium excretion increases, even at rest, along with fluid retention due to increased aldosterone, yet paradoxically, blood volume may decrease. Electrolyte losses—especially magnesium and potassium—can increase. Women are more prone to cramping, fatigue, and dehydration symptoms, research suggests that magnesium needs may increase by 10–20% in the luteal phase to support energy production and reduce these symptoms. Similarly, potassium intake is important to counterbalance sodium and maintain cardiovascular stability during this phase.

• Water Intake: 40-45ml/kg

• Magnesium: 350-400mg

• Potassium: 3000-3400mg

• Calcium: 1000-1500mg

• Sodium: 1500-2000mg

Food Sources of Electrolytes

People often associate electrolytes with sports drinks or tablets, however, there are high amounts found in these food sources:

Magnesium: Dark leafy greens, pumpkin seeds, avocados, quinoa, tofu, mackerel, black beans, dark chocolate, almonds, and edamame.

Calcium: Sardines, Greek yoghurt, almonds, tofu, figs, chia seeds, broccoli, sesame seeds (tahini), and kale.

Potassium: Sweet potato, banana, coconut water, mushrooms, zucchini, salmon, avocado, spinach, beans, and lentils.

Sodium: Pink Himalayan salt, anchovies, beetroot, celery, bone broth, olives, and pickled or fermented vegetables.

Practical Tips for Staying Hydrated

1. Start your day with 250ml of warm water + lemon or electrolytes

2. Keep a large thermos of herbal tea or plain water nearby

3. Eat water-rich foods like soups or bone broth

4. Drink intentionally—not just when thirsty

5. Hydrate before and after training, especially during the luteal phase

6. Track your fluid intake if you struggle to remember—consume at least 250ml every hour, plus 1-2 glasses around exercise, and add a little more during the luteal phase

Hydration isn’t seasonal—and for women, it’s not static. Hormonal changes throughout the menstrual cycle significantly affect fluid and electrolyte requirements. In colder months, it’s especially important to stay mindful of hydration, as thirst perception drops, yet fluid loss and electrolyte needs continue, especially during exercise or the luteal phase.

By understanding how the female body’s needs shift across the month and seasons, we can take a more personalized, proactive approach to staying healthy, energized, and hormonally balanced.