Ray Peat on Water and Hydration

Short answer: Ray Peat warned against forcing water. He wrote that drinking beyond thirst, especially on a low-salt diet, dilutes the blood, and that a person with low thyroid function, who already retains water and loses sodium, can be seriously harmed by it.

What Ray Peat wrote about water

He describes meeting many people who believed they should drink eight glasses of water a day on top of their food, even when not thirsty. Source: Water: swelling, tension, pain, fatigue, aging

A healthy person adapts to extra water with a low-salt diet. For a hypothyroid person, he wrote, the combination can have disastrous effects. Source: Water: swelling, tension, pain, fatigue, aging

Hypothyroid people lose sodium easily, and estrogen increases water retention without holding sodium to match. Low thyroid with high estrogen therefore means both edema and low blood sodium. Source: Epilepsy and Progesterone

Too much water can cause seizures. Neurologists once tested for epilepsy by having the patient drink a pint of water. Source: Water: swelling, tension, pain, fatigue, aging, Epilepsy and Progesterone

Thyroid hormone and carbon dioxide protect against water retention. Raising carbon dioxide reduces the water content of tissues. Source: Water: swelling, tension, pain, fatigue, aging

Water for constipation does not work the way people think, because it is absorbed high in the intestine long before it reaches the colon. Source: Water: swelling, tension, pain, fatigue, aging

Every kind of stress, fatigue and injury makes tissues take up water. He wrote that swelling is a basic feature of the stressed cell. Source: Meat physiology, stress, and degenerative physiology, Lactate vs. CO2 in wounds, sickness, and aging; the other approach to cancer

Sodium keeps water and albumin inside the blood vessels, so salt supports blood volume while plain water does not. Source: When energy fails: Edema, heart failure, hypertension, sarcopenia, etc

What he suggested in practice

• Drink to thirst.
• Salt food freely, especially if thyroid function is low.
• Get fluid from milk and fruit juice, which carry minerals and sugar.

Where he wrote about it

This topic comes up in 86 of the articles on his site. These are the most relevant ones:

• Water: swelling, tension, pain, fatigue, aging · original on raypeat.com ↗
• Fatigue, aging, and recuperation · original on raypeat.com ↗
• Cataracts: water, energy, light, and aging · original on raypeat.com ↗
• The transparency of life: Cataracts as a model of age-related disease · original on raypeat.com ↗
• Pathological Science & General Electric: Threatening the paradigm · original on raypeat.com ↗
• Membranes, plasma membranes, and surfaces · original on raypeat.com ↗
• Growth hormone: Hormone of Stress, Aging, and Death? · original on raypeat.com ↗
• When energy fails: Edema, heart failure, hypertension, sarcopenia, etc · original on raypeat.com ↗

My take

Drinking a lot of plain water can lower your blood volume. Water in your stomach is not enough. To get it into the bloodstream and keep it there, you need minerals.

Quick answers

What did Ray Peat say about drinking water?

That people should not force water beyond thirst, because excess water with too little salt dilutes the blood, and is especially harmful when thyroid function is low.

What did Ray Peat say about water retention?

That it is a sign of stress and low energy, promoted by low thyroid function and estrogen, and reduced by thyroid hormone, carbon dioxide and adequate sodium.