Research
Hormonal
Leptin acts as a critical signal from adipose tissue to the hypothalamus to regulate the hypothalamus-pituitary-thyroid axis, specifically by stimulating TRH expression and TSH secretion during energy sufficiency.
Your body uses leptin (a hormone from fat cells) to tell your brain how much energy you have. When you fast or lose weight, leptin drops, signaling your brain to slow down thyroid function to save energy. This is a normal survival mechanism.
GoodSupportsHIGH confidence
Taken together, these data support the view that a reduction in serum leptin levels acts as a peripheral signal capable of directly inhibiting the hypothalamus–pituitary–thyroid axis. This function, being exerted at the hypothalamic level through an inhibition of TRH expression and secretion, would be an ancestral one, aimed at saving energy in conditions of food shortage.
Why this rating
Supported by murine models and some human studies showing leptin's effect on TSH.
Source
MECHANISMS IN ENDOCRINOLOGY: The crosstalk between thyroid gland and adipose tissue: signal integration in health and disease
Ferruccio Santini et al. · European Journal of Endocrinology · 2014
DOI 10.1530/eje-14-0067
narrative_reviewCited 230×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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