| There are certainly complicated physiological effects caused by fasting however the heterogeneity and limited number of studies make it difficult to draw definitive conclusions Mental deficits are associated with fasting across a review of a variety of studies https://pubmed.ncbi.nlm.nih.gov/34595721/ Fasting can also cause other mental issues:
"Additionally, fasting was found to be associated with alterations in mood, including worsened mood, heightened irritability, difficulties concentrating, and increased fatigue, as well as an increase in depressive score in mentally healthy humans" https://www.nature.com/articles/s41598-022-11639-1 All in all it remains highly suspect that fasting has anything but long term and short term negative effects. As I said in another comment it makes sense to me that so called "health fasting" tends to be more common among people who are already vulnerable and at risk for disordered eating. I will continue to spread awareness about the link between "health fasting" (as well as other health and diet based fads) and actual life threatening eating disorders. There is a huge lack of research into eating disorders generally and even less research into the interaction of health fads and eating disorders. I encourage everyone to advocate and support any and all research in this area to combat misinformation spread by "health" gurus and companies looking to make a quick buck. |
It’s likely that the downsides are a necessary trade off for a longer lifespan. The body reduces its metabolism in order to conserve resources and survive long enough until access to sustenance returns. The most dramatic change is the loss in libido; maintaining an active reproductive system has significant metabolic demands, so they are deprioritised. It’s possible that what we consider “healthy baseline” in the contemporary age of caloric abundance is actually a hyper-active state that accumulates rapid damage and dietary restriction brings metabolism down to a frugal and entropy-conserving state.
Edit: those two fantastic papers should provide you with all the help you will ever need in your efforts:
http://www2.hawaii.edu/~vitousek/CRAN2.pdf
http://www2.hawaii.edu/~vitousek/CRAN1.pdf