Test Your Thyroid Function

Typically, it is normal to wake up with a lower pulse rate, which then increases to 80 - 90 beats per minute after breakfast and remains elevated throughout the day (Table 4) (Peat, 2008, p. 5; Ray Peat Clips, 2016d; Functional Performance, 2023).

Goitrogens can adversely affect thyroid health by hindering the thyroid gland’s ability to absorb iodine, an essential element for the synthesis of thyroid hormones (Cleveland Clinic, 2019).

While temperature and pulse rate typically rise after a balanced breakfast in healthy individuals, those with hypothyroidism may experience a decrease in one or both of these measurements (Peat, 2008, p. 5; Ray Peat KMUD, 2013).

The production of T3 is further compromised by physical or mental stress, as stress hormones (cortisol and adrenaline) directly interfere with the T4 to T3 conversion process (Peat, 2008, p. 3).

Low blood sugar (hypoglycemia) and a lack of selenium are also known to impede the conversion of T4 to T3

Dr. Ray Peat emphasized that he never encountered a person with a TSH level over 2 mIU/L who was in good health.

As previously noted, the liver is the primary organ responsible for converting T4 to T3. Consequently, compromised liver function can lead to hypothyroidism (Peat, 2001a, p. 73).

He noted that healthy individuals with good thyroid function usually have an average resting pulse rate of about 85 beats per minute, whereas those in less-than-optimal health often have rates around 70 beats per minute (Peat, 2008, p. 4).

Measuring pulse and temperature upon waking and assuming these metrics accurately reflect thyroid function can be misleading due to the influence of stress hormones (Peat, 2008, p. 5).