Lack of ‘hunger hormone’ may help snakes survive months between meals

Embargoed until: Publicly released: 2026-02-04 11:01

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PHOTO: Larisa Steele on Unsplash

Unlike most animals, including humans, snakes appear to have lost the ‘hunger hormone’ ghrelin, which regulates appetite and signals the body to use fat stores for energy during fasting. European researchers studied the genes of 112 reptile species, including tuatara, and found that the snakes had lost the gene needed to produce ghrelin. Chameleons (which have a similar 'sit and wait' hunting strategy to snakes), as well as two species of lizard, had also lost the ghrelin gene independently during their evolution. The researchers speculated that this could be part of the evolutionary changes that help snakes and chameleons conserve energy during long periods of fasting between meals.

News release

From: The Royal Society

Snakes, chameleons and toadhead agamids have lost two genes, ghrelin and MBOAT4, which, in most vertebrates, play central roles in regulating appetite, metabolism, and energy balance. Their absence suggests that these groups evolved unique physiological mechanisms to manage feeding and energy use, independent of this ancient hormonal system. This discovery provides new insight into how extreme metabolic adaptations shaped the evolution of feeding behaviours associated with these groups, such as long fasting periods and infrequent feeding.

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Journal/
conference: Open Biology

Research:Paper

Organisation/s: University of Porto, Portugal

Funder: The PhD fellowship for RRP (2020.08608.BD) was granted by Fundação para a Ciência e Tecnologia. This research was also funded by national funds through FCT, I.P., and by the European Commission’s Recovery and Resilience Facility, within the scope of UID/04423/2025 (https://doi.org/10.54499/UID/04423/2025), UID/PRR/04423/2025 (https://doi.org/10.54499/UID/PRR/04423/2025), and LA/P/0101/2020 (https:// doi.org/10.54499/LA/P/0101/2020). JS was supported by research grant no 42153 from VILLUM FONDEN. RDF thanks the VILLUM FONDEN for the Center for Global Mountain Biodiversity grant no 25925.

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