The Connection Between Circadian Rhythms, Fasting, and Lifespan Extension

The Connection Between Circadian Rhythms, Fasting, and Lifespan Extension

 

The rise in promotion of healthy eating and exercising is clearly evident within minutes

of opening a social media app. Consumer values are changing, and likely with probable cause,

as obesity is the cause of many life-threatening issues such as hypertension, type 2 diabetes,

coronary heart disease, osteoarthritis, and certain types of cancer.  Although many people

attempt to diet or exercise in order to benefit their health or lose some extra weight, few

people realize the implications of circadian rhythms in weight loss/gain. What if eating

properly and taking the impact of circadian rhythms into account could not only

ameliorate one’s health, but also extend their lifespan?  

 

A research paper presented in our class, titled “Central and Peripheral Control

of Circadian Feeding Rhythms” by Cavanaugh et al. found that feeding rhythms

and food intake were both decreased in fruit flies which were genetically

manipulated to have simultaneous disruptions in molecular clock neurons

in peripheral tissues. The larger implications of this study conclude that the

proper function of molecular clock neurons in the central nervous system and

peripheral nervous system are both vital in the regulation of feeding rhythms,

but another implication lies in the possible role of circadian rhythms in targeting

eating patterns.

 

Another article, “Circadian Autophagy Drives iTRF-Mediated Longetivity” by

Ulgherait et al. focused on the dependence of time-restricted feeding (TRF) on

circadian rhythm function. While many popular weight-loss strategies target restricting

calories or nutrients, TRF is novel in that it only limits the hours of food intake.

The researchers created an intermittent time-restricted feeding (iTRF) program

for fruit flies in which flies had limited access to food. Initially, control flies had 24 hour

access to their food, and flies on the TRF schedule had 12 hour access with lights on and

12 hour fasting with lights off. It was discovered that the standard 12h:12h TRF schedule

did not result in an extended lifespan, whereas 24 hours of fasting with one or two days

of 24 hour access actually shortened fly lifespan. However, through methods of trial and

error, researchers were able to discover that fasting for 20 hours every other day and

having 24 hour access to food on the rest days in between significantly extended the

fly lifespan when done 30-day trials. They also found that flies on the iTRF regimen

had a lower age-related decline in climbing activity in comparison to control flies.

Flies on the iTRF regimen also had lower levels of age-related protein aggregation,

as demonstrated by levels of extractable Triton-insoluble fractions and western blot

analyses for ubiquitin. Another marker of aging, intestinal function, was also decreased

in iTRF flies in comparison to controls. Overall, this research concludes that iTRF has

proven to result in a decline in several age-related markers, showing that iTRF is capable

of improving healthspan and hindering aging processes. The study also confirmed that

TRF can improve circadian gene expression and iTRF requires functioning circadian

clocks in order to significantly extend lifespan. It was also found that only night-based

fasting is necessary for iTRF to produce these results. 

 

All in all, the results of these two studies confirm that circadian rhythms have a significant

role in feeding patterns in fruit flies, and that adjusting eating according to hours instead

of calories can extend lifespan, healthspan, and delay the onset of aging processes in fruit

flies. More research is necessary in order to confirm the same benefits in human subjects,

but the possibility of this remains hopeful, as flies share 70% of human genes and have

been successfully used in previous studies to discover what is currently known about

human circadian rhythms. 

 

 

Works Cited

Central and Peripheral Clock Control of Circadian Feeding Rhythms

Fulgham CV, Dreyer AP, Nasseri A, Miller AN, Love J, Martin MM, Jabr DA, Saurabh S,

Cavanaugh DJ. Central and Peripheral Clock Control of Circadian Feeding Rhythms.

J Biol Rhythms. 2021 Dec;36(6):548-566. doi: 10.1177/07487304211045835. Epub

2021 Sep 22. PMID: 34547954.

Circadian Autophagy Drives iTRF-Mediated Longetivity

Ulgherait M, Midoun AM, Park SJ, Gatto JA, Tener SJ, Siewert J, Klickstein N, Canman

JC, Ja WW, Shirasu-Hiza M. Circadian autophagy drives iTRF-mediated longevity.

Nature. 2021 Oct;598(7880):353-358. doi: 10.1038/s41586-021-03934-0. Epub 2021 Sep 29.

PMID: 34588695.