So I’m a physician and I support most things people do to import their health but I do try to make sure they’re fully informed. In terms of fasting, this cohort study found an adverse association between fasting and cardiovascular death. There are limitations to the study (self-reported diet, etc.) but it followed 20,000 people for 8yrs which is pretty good. Definitely need more study in this area, especially considering the complexity of human metabolism. Here’s the highlights from the study but the full text is available at that link:

• People who followed a pattern of eating all of their food across less than 8 hours per day had a 91% higher risk of death due to cardiovascular disease.
• The increased risk of cardiovascular death was also seen in people living with heart disease or cancer.
• Among people with existing cardiovascular disease, an eating duration of no less than 8 but less than 10 hours per day was also associated with a 66% higher risk of death from heart disease or stroke.
• Time-restricted eating did not reduce the overall risk of death from any cause. An eating duration of more than 16 hours per day was associated with a lower risk of cancer mortality among people with cancer.