For passive heat exposure (i.e. no exercise), the Finnish-style dry sauna remains the most efficient single modality for driving sweat production:

• Dry (Finnish) sauna (80–90 °C, 10–20 % RH) ▶︎ ~0.7 kg body-mass loss per hour
• Wet (steam) sauna (45 °C, 100 % RH) ▶︎ ~0.36 kg/h

1. Greater body-mass losses were observed after a dry sauna bath compared to a wet sauna (−0.72 kg vs. −0.36 kg over similar durations)

Why dry > steam?

• Low RH allows evaporation of sweat as fast as it’s produced.
• High air temperature (vs. infrared’s lower 40–60 °C) kicks core-to-skin heat transfer into overdrive.

Infrared vs. Traditional Sauna

• Infrared saunas operate at 40–60 °C, requiring 30–45 min to match the sweat of a 15–20 min traditional sauna session.
• For short, intense sweating, traditional dry saunas are superior; for longer, milder sessions, far-infrared can be an alternative.

Complete replacement of water duration ("practical 100 %")

Because replacement follows an exponential decay curve, “100 %” never truly occurs, but in practice:

• ≈ 86 % replaced after 2 half-lives (≈ 15 days)
• ≈ 95 % replaced after 3 half-lives (≈ 22 days)
• ≈ 98 % replaced after 4 half-lives (≈ 30 days)

Mean residence time (MRT) of ingested water is ~10.3 ± 1.5 days, implying ~50 days for essentially complete elimination of initial water.

Half of your body water is replaced in 7–10 days. >95 % of it is turned over within 3–4 weeks. Practically all original water molecules are gone by ~30–50 days, assuming you continue to drink and excrete normally.

Sources:

• https://pmc.ncbi.nlm.nih.gov/articles/PMC6360547/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC5941775/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC3351614/

Optimal Rehydration

Water in a glass bottle, recyclable with a stainless steel lid (grade 304 or 316) with a food-grade silicone gasket (preferably platinum-cured).

Formula 1: we only want to put back in what sweat took out, adding nothing and leaving nothing.

Sweat is hypotonic to blood — meaning it contains more water than electrolytes — but it still carries enough sodium, potassium, and chloride that replacing only water can dilute blood electrolyte levels dangerously (→ hyponatremia).

Optimal Rehydration Water Formula (Per 1 Liter of Water)

Component Amount Purpose

• Sodium (Na⁺) 800–1000 mg (35–45 mmol) Replaces sodium lost in sweat; key for plasma osmolality and nerve/muscle function
• Potassium (K⁺) 200–400 mg (5–10 mmol) Maintains intracellular balance; offsets muscle cramps
• Magnesium (Mg²⁺) 30–50 mg (1.25–2 mmol) Supports enzyme function, reduces fatigue
• Calcium (Ca²⁺) 50–100 mg (1.25–2.5 mmol) Helps in nerve conduction, muscle contraction
• Chloride (Cl⁻) 1200–1500 mg (34–42 mmol) Balances Na⁺ and maintains osmotic pressure
• Water (H₂O) 1000 ml Fluid replacement medium

Target osmotic pressure: ~270–295 mOsm/kg (same as blood plasma), this formula aims to maintain isotonicity or very slightly hypotonic (~240–280 mOsm/kg), so water absorption is maximized and safely distributed between intra/extracellular fluid.

Ultimate Sauna Flush Matrix (Per 1 L of Base Water)

Component Dose / L Purpose & Notes

Electrolyte Foundation

• Sodium (Na⁺) 1 000 mg (43 mmol) Matches high sweat sodium losses; maintains plasma volume
• Potassium (K⁺) 300 mg (7.7 mmol) Intracellular balance; anti-cramp
• Chloride (Cl⁻) 1 200 mg (34 mmol) Osmotic counterion
• Magnesium (Mg²⁺) 50 mg (2.1 mmol) Enzyme cofactor, muscle relaxation
• Calcium (Ca²⁺) 100 mg (2.5 mmol) Nerve/muscle support
• Betaine (Trimethylglycine) 2 g Cellular osmolyte, supports liver methylation, may aid mild diuresis
• Taurine 1 g Cell volume regulation, antioxidant
• Inositol 500 mg Osmolyte, insulin-sensitizer

Chelators & "Detox" Agents

• EDTA (disodium) 50 mg Strong divalent-cation chelator; binds heavy metals in plasma (oral use controversial)
• Alpha-lipoic acid (ALA) 200 mg Mitochondrial antioxidant, metal chelator
• N-acetyl cysteine (NAC) 600 mg Boosts glutathione, supports liver detox pathways
• Cilantro extract (standardized) 150 mg Traditional chelator for mercury/lead; limited evidence
• Chlorella powder 500 mg Binds toxins in gut, provides chlorophyll antioxidant

Adaptogens & Circulation Boosters

• Panax ginseng extract (standardized ginsenosides) 200 mg Improves heat tolerance, circulation
• Rhodiola rosea extract (3% rosavins) 100 mg Stress resilience, may support vasodilation
• Beetroot powder (nitrate source) 3 g Increases NO, enhances microcirculation

Mild Diuretic & Vasodilator Precursors

• ?

pH & Buffering

• Sodium citrate 500 mg pH buffer, enhances palatability

Flavor & Palatability

• Natural lemon & ginger essence a few drops Improves taste, may aid gastric motility

Estimated Osmolality: approximately 300–350 mOsmol/kg—slightly hypertonic to drive fluid into plasma quickly

⚠️ Safety & Practical Notes

EDTA, high-dose NAC, ALA, chlorella and cilantro can all cause gastrointestinal upset, electrolyte imbalances, or unwanted mineral chelation if mis-dosed. Long-term use of chelators can deplete essential minerals—rotate or cycle no more than 2–3 days in a row.

How to Use: Mix all dry components into 1 L of ultra-pure water (glass or steel container). Chill to ~15 °C. Sip 200–300 mL per 10 minutes leading up to your sauna or sweat session. Post-sauna, drink another 300–500 mL to replenish and prepare for the next round.