Since lockdown I have been consistently eating 1 meal a day, with occasional 2 day fasts and rarely 3-4 day fasts. It is so natural to me now that on my last stay in London I got 2 days in to the trip when I suddenly realised I'm in London, surrounded by amazing food I can't get at home, I should eat more and enjoy. So I gorged on Indian, Jamaican, Vietnamese, I was surprised how much I could put away, so much walking had stimulated my appetite.

On the science of fasting. It was Ancel Keys whose research, in the 60s, led to the invention of the Mediterranean diet as a way of reducing obesity and heart disease in America. Keys work provided the intellectual justification for the McGovern senate committee, in 1977, to propose radical changes to diet and to government policy. The top-down approach to the national diet led the government to adopt the Low Fat Diet as policy, e.g. the https://en.m.wikipedia.org/wiki/National_School_Lunch_Act

Can you spot 1977 on this obesity chart?
https://www.ncbi.nlm.nih.gov/books/NBK19623/figure/chartbook...

Since Keys death, dissenting voices have gotten louder:
"In the December 2004 issue of your journal, in his column, Geoffrey Cannon referred to Ancel Keys’ Seven Countries Study and the fact that Keys and his colleagues seemed to have ignored the possibility that Greek Orthodox Christian fasting practices could have influenced the dietary habits of male Cretans in the 1960s. For this reason, we had a personal communication with Professor Christos Aravanis, who was responsible for carrying out and following up the Seven Countries Study in Greece. Professor Aravanis conﬁrmed that, in the 1960s, 60% of the study participants were fasting during the 40 days of Lent, and strictly followed all fasting periods of the church according to the Greek Orthodox Church dietary doctrines. These mainly prescribe the periodic abstention from meat, ﬁsh, dairy products, eggs and cheese, as well as abstention from olive oil consumption on certain Wednesdays and Fridays. However, it is indeed the case that this was not noted in the study, and no attempt was made to differentiate between fasters and non-fasters. In our view this was a markable and troublesome omission. The Greek Orthodox Church prescribes almost 180 days of fasting per year. It is unknown to what extent the Cretans who were the original subjects of the Seven Countries Study and who fasted during Lent also followed the precepts of their Church throughout the year, and thus on how many days in total and to what extent the Cretan participants of the Seven Countries Study fasted"
https://www.researchgate.net/publication/7530689_The_Seven_C...

The fatal blow to Keys' lipid hypothesis was dealt in 2016 after data from another Keys' experiment was re-examined.
"Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment" concludes:

Results – The intervention group had significant reduction in serum cholesterol compared with controls (mean change from baseline −13.8% v −1.0%; P<0.001). Kaplan Meier graphs showed no mortality benefit for the intervention group in the full randomized cohort or for any prespecified subgroup. There was a 22% higher risk of death for each 30 mg/dL (0.78 mmol/L) reduction in serum cholesterol in covariate adjusted Cox regression models (hazard ratio 1.22, 95% confidence interval 1.14 to 1.32; P<0.001). There was no evidence of benefit in the intervention group for coronary atherosclerosis or myocardial infarcts. Systematic review identified five randomized controlled trials for inclusion (n=10 808). In meta-analyses, these cholesterol lowering interventions showed no evidence of benefit on mortality from coronary heart disease (1.13, 0.83 to 1.54) or all cause mortality (1.07, 0.90 to 1.27).
Conclusions – Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836695/