This 2021 rodent study induced metabolic syndrome with a high-fat diet and switching light-dark cycles every week for 14 weeks. While continuing to disrupt circadian rhythms for ten more weeks, most metabolic effects were reversed by adding either 5% β-glucan, 5% inulin, or .05% melatonin to subjects’ high-fat diet:
“Both prebiotics (oat β-glucan and chicory inulin) and melatonin significantly reversed circadian disruption-induced metabolic syndrome (CDIMS) and alteration of gut microbiota composition. Both prebiotics also reversed increase in body weight and liver weight-to-body weight ratio, and decrease in fasting plasma insulin. Only oat β-glucan reduced plasma leptin and alleviated glucose intolerance.
All dietary interventions enhanced species richness. In altering gut microbiota, oat β-glucan reversed populations of 7 bacterial genera and increased butyrate producers including Ruminococcaceae and Lachnospiraceae which enhance gut barrier protection and regulate glucose homeostasis.
Though melatonin cannot be fermented in the gut as prebiotics, oral administration of exogenous melatonin absorbed via melatonin receptors concentrated in the intestine has been demonstrated for its effects on shaping gut microbiota. There is currently no concrete mechanism explaining how melatonin affects gut microbial ecology. We postulate that the ability of melatonin to alleviate CDIMS is not governed by changes of SCFAs, but possibly a direct host effect which subsequently affects other metabolites such as bile acids.
In contrast with melatonin, oligomeric chicory inulin as a fermentable fiber mainly affects gut microbiota which affects the host indirectly. For polymeric oat β-glucan, our results suggested that it is probably a combination of both direct and indirect effects to the host, and this is a special property not yet evidenced in other polysaccharides.
Approximately 35% of human gut microbiota undergo temporal rhythmicity. We speculate that prebiotics may affect diurnal oscillations of gut microbiota, its capacity for energy harvest and production of metabolites, which subsequently affect host central circadian clocks through gut-microbiome-brain axis, in which gut microbes interact with central nervous system via nervous, endocrine, and immune signaling pathways.”
https://www.sciencedirect.com/science/article/abs/pii/S0144861721006032 “Circadian disruption-induced metabolic syndrome in mice is ameliorated by oat β-glucan mediated by gut microbiota” (not freely available)
Humans could avoid a high-fat diet, of course. My main experiences with circadian disruptions were 18-hour days of submarine life. That didn’t cause metabolic syndrome, just disorientation to the real world after surfacing.
The end of fig season