Peat Archive

Body temperature is one of Ray Peat's key diagnostic indicators of metabolic health. He emphasized that a waking temperature near 97.8°F (36.6°C) rising to 98.6°F (37°C) by midday, combined with a pulse of 75-85 beats per minute, indicates adequate thyroid function and metabolic rate. Consistently low temperatures signal hypothyroidism and metabolic insufficiency, regardless of what blood tests show.

Peat argued that cold exposure, while trendy, is a biological stressor that raises cortisol, suppresses thyroid function, and promotes the release of free fatty acids. He recommended warm environments, warm drinks, and adequate caloric intake to support body temperature. He noted that fever itself is a healing response (not just a symptom to suppress), and that the body's ability to mount a fever declines with age as metabolic capacity decreases.