From what I’ve read fasting is more of an intervention for metabolic issues, helping to reduce insulin levels more dramatically. The study you linked to seems to support this.

> However, FBS improved insulin sensitivity, with significant reductions in fasting insulin

The issue, and why I think we’ve seen several high profile fasting advocates stop, is because they weren’t metabolically unhealthy, but were on extreme fasting protocols as if they were.

The way I read it, if you’re significantly overweight and have high insulin levels (type 2 diabetes or pre-diabetes), fasting can help get things under control quickly. However, once a person has regained metabolic flexibility and health, moving to something more balanced is likely a good idea. Just avoiding going back to a lifestyle that leads to chronically high insulin levels. Some amount of fasting probably makes sense, as has been practiced by most major religions in some form for thousands of years, but not to the same extreme as during the intervention.