Torpor, Circadin Rhythms and the AhR: Obesity Explained, Episode 4

Episode 4 of Obesity Explained is out!

Watch The Video!

Video Summary

It’s January. Days are short, the light is dim. This one is about circadian rhythms, daylength, body weight and torpor.

My working hypothesis is that the Aryl Hydrocarbon Receptor is A, if not THE, master regulator of torpor. Kynurenine is a tryptophan metabolite that is elevated in hibernating mammals during the fattening stage of their yearly cycle. Kynuernine is elevated to a similar extent in obese humans.

An elevated AhR shifts your metabolism into a torpor-like state that favors fat storage. One of the ways it does this is by shutting down circadian rhythms. The AhR is closely related to the CLOCK gene – the transcription factor that controls circadian rhythms. Transcription factors are genes that control the expression of other genes. When activated, the AhR displaces the CLOCK gene at the site of the DNA where clock would normally attach and turn on genes that have a circadian rhythm. The AhR blocks transcription of these genes.

The graph on the left is from a 1984 paper of mammalian hibernation. It showed that melatonin – a gene under circadian control – has a circadian pattern in the summer but is totally squelched in the winter. The graph on the right is from a Nature paper from 2018 showing that activating the AhR squelches the expression levels of circadian controlled genes.

NAD+ levels are controlled in a Circadian fashion. The enzyme NAMPT recycles NAD+ after it is converted to nicotinamide by NADase enzymes like the sirtuins, PARPs and CD38. Mice lacking the CLOCK gene – the very gene displaced by an activated AhR – have very low levels of NAD+ and become very fat.

Humans with a less active version of the clock gene experience weight loss stall on a low calorie diet.

Theabrownin and Pu Erh Tea

Pu Erh tea is a fermented tea that has a high quantity of dark brown pigments called theabrownin (brown pigment from tea). The tea and theabrownin reverse the effects of a dysregulated circadian rhythm, probably by inhibiting the AhR and thus lowering kynurenine levels. Kynurenine and the AhR are regulated in a positive feedback loop. The AhR upregulates an enzyme called IDO1 which creates kynuerenine which activates the AhR. Pu Erh tea breaks this loop.

Red and light blue lines are kynurenine levels of mice with normal sleep. Purple are mice with disrupted sleep drinking water. Turquoise is mice with disrupted sleep drinking Pu Erh tea. Kynurenine levels are largely restored.

I present evidence in the video that the mechanism of action of Pu Erh tea is likely that theabrownin is a direct inhibitor of the AhR.


Bartness, T. J., & Wade, G. N. (1985). Photoperiodic control of seasonal body weight cycles in hamsters. In Neuroscience & Biobehavioral Reviews (Vol. 9, Issue 4, pp. 599–612). Elsevier BV. https://doi.org/10.1016/0149-7634(85)90006-5

Cappuccio, F. P., Taggart, F. M., Kandala, N.-B., Currie, A., Peile, E., Stranges, S., & Miller, M. A. (2008). Meta-Analysis of Short Sleep Duration and Obesity in Children and Adults. In Sleep (Vol. 31, Issue 5, pp. 619–626). Oxford University Press (OUP). https://doi.org/10.1093/sleep/31.5.619

Danilenko, K. V., Mustafina, S. V., & Pechenkina, E. A. (2013). Bright Light for Weight Loss: Results of a Controlled Crossover Trial. In Obesity Facts (Vol. 6, Issue 1, pp. 28–38). S. Karger AG. https://doi.org/10.1159/000348549

Fader, K. A., Nault, R., Doskey, C. M., Fling, R. R., & Zacharewski, T. R. (2019). 2,3,7,8-Tetrachlorodibenzo-p-dioxin abolishes circadian regulation of hepatic metabolic activity in mice. In Scientific Reports (Vol. 9, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1038/s41598-019-42760-3

FUKUDA, I., SAKANE, I., YABUSHITA, Y., SAWAMURA, S., KANAZAWA, K., & ASHIDA, H. (2005). Black Tea Theaflavins Suppress Dioxin-Induced Transformation of the Aryl Hydrocarbon Receptor. In Bioscience, Biotechnology, and Biochemistry (Vol. 69, Issue 5, pp. 883–890). Informa UK Limited. https://doi.org/10.1271/bbb.69.883

Garaulet, M., Corbalán, M. D., Madrid, J. A., Morales, E., Baraza, J. C., Lee, Y. C., & Ordovas, J. M. (2010). CLOCK gene is implicated in weight reduction in obese patients participating in a dietary programme based on the Mediterranean diet. In International Journal of Obesity (Vol. 34, Issue 3, pp. 516–523). Springer Science and Business Media LLC. https://doi.org/10.1038/ijo.2009.255

Gehrke, S., Rice, S., Stefanoni, D., Wilkerson, R. B., Nemkov, T., Reisz, J. A., Hansen, K. C., Lucas, A., Cabrales, P., Drew, K., & D’Alessandro, A. (2019). Red Blood Cell Metabolic Responses to Torpor and Arousal in the Hibernator Arctic Ground Squirrel. In Journal of Proteome Research (Vol. 18, Issue 4, pp. 1827–1841). American Chemical Society (ACS). https://doi.org/10.1021/acs.jproteome.9b00018

Hu, S., Luo, L., Bian, X., Liu, R. H., Zhao, S., Chen, Y., Sun, K., Jiang, J., Liu, Z., & Zeng, L. (2022). Pu-erh Tea Restored Circadian Rhythm Disruption by Regulating Tryptophan Metabolism. In Journal of Agricultural and Food Chemistry (Vol. 70, Issue 18, pp. 5610–5623). American Chemical Society (ACS). https://doi.org/10.1021/acs.jafc.2c01883

Khazaal, A. Q., Jaeger, C. D., Bottum, K. M., & Tischkau, S. A. (2018). Environmental factors act through aryl hydrocarbon receptor activation and circadian rhythm disruption to regulate energy metabolism. In Journal of Receptor, Ligand and Channel Research: Vol. Volume 10 (pp. 13–24). Informa UK Limited. https://doi.org/10.2147/jrlcr.s133886

Monteleone, P., Tortorella, A., Docimo, L., Maldonato, M. N., Canestrelli, B., De Luca, L., & Maj, M. (2008). Investigation of 3111T/C polymorphism of the CLOCK gene in obese individuals with or without binge eating disorder: Association with higher body mass index. In Neuroscience Letters (Vol. 435, Issue 1, pp. 30–33). Elsevier BV. https://doi.org/10.1016/j.neulet.2008.02.003

Nakahata, Y., Sahar, S., Astarita, G., Kaluzova, M., & Sassone-Corsi, P. (2009). Circadian Control of the NAD + Salvage Pathway by CLOCK-SIRT1. In Science (Vol. 324, Issue 5927, pp. 654–657). American Association for the Advancement of Science (AAAS). https://doi.org/10.1126/science.1170803

Tournier, B. B., Menet, J. S., Dardente, H., Poirel, V. J., Malan, A., Masson-Pévet, M., Pévet, P., & Vuillez, P. (2003). Photoperiod differentially regulates clock genes’ expression in the suprachiasmatic nucleus of Syrian hamster. In Neuroscience (Vol. 118, Issue 2, pp. 317–322). Elsevier BV. https://doi.org/10.1016/s0306-4522(03)00008-3

Turek, F. W., Joshu, C., Kohsaka, A., Lin, E., Ivanova, G., McDearmon, E., Laposky, A., Losee-Olson, S., Easton, A., Jensen, D. R., Eckel, R. H., Takahashi, J. S., & Bass, J. (2005). Obesity and Metabolic Syndrome in Circadian Clock Mutant Mice. In Science (Vol. 308, Issue 5724, pp. 1043–1045). American Association for the Advancement of Science (AAAS). https://doi.org/10.1126/science.1108750

Vaněček, J., Janský, L., Illnerová, H., & Hoffmann, K. (1984). Pineal melatonin in hibernating and aroused golden hamsters (Mesocricetus auratus). In Comparative Biochemistry and Physiology Part A: Physiology (Vol. 77, Issue 4, pp. 759–762). Elsevier BV. https://doi.org/10.1016/0300-9629(84)90197-x

Xiao, Y., Li, M., Wu, Y., Zhong, K., & Gao, H. (2020). Structural Characteristics and Hypolipidemic Activity of Theabrownins from Dark Tea Fermented by Single Species Eurotium cristatum PW-1. In Biomolecules (Vol. 10, Issue 2, p. 204). MDPI AG. https://doi.org/10.3390/biom10020204

Please follow and like us:

1 thought on “Torpor, Circadin Rhythms and the AhR: Obesity Explained, Episode 4”

  1. Hi Brad,

    I’m curious if you think that Pu’ Erh Tea needs to be taken after meals to be effective.

    I’ve been drinking it first thing in the morning and eating a late afternoon/early evening OMAD most days. Unfortunately, I’m caffeine sensitive, so i don’t mess with tea or coffee after noon.

    I usually don’t get hungry during the day (I’m the sort of glutton who eats so much that even eating once a day i have trouble losing weight), and even if i did, it’s pretty hard to find quick, easy food that’s low in PUFA. It’s easier for me to avoid PUFA by making everything from scratch at home.

    I’ve been messing around with different ideas from this blog and the Ray Peat forums and i keep yo-yoing. Been losing and gaining the same 15 pounds sonce January 2022.

    I drink black Pu’ Erh Tea (a 16 ounce cup made with 3 tbsp of loose leaf) every morning… Sometimes i have coffee after, but not every day. Sometimes, i have coconut oil before my tea, but not always.

    Do you have any ideas that may help?
    Are you still using pyruvate and l-carnitine (if so, are you still steadily dropping weight)?

    I’ve previously tried ALA supplements and stearic acid. Neither seemed to make any difference.

    Any advice on which supplements you sell/advocate using would work best for my situation?

Leave a Comment

Your email address will not be published.