I only skimmed very quickly, but I didn't see any evidence that the improvements were due to intermittent fasting rather than the calorie restriction and weight loss that naturally occurs if a person doesn't eat for 3 days/week or 18 hours every day (the two regimens I recall from the article).

Even if there were a ton of data on safety and efficacy (there is not) I wouldn't generally recommend an extreme lifestyle modification unless a pt tried a more modest intervention without results. But the pts who follow recommendations on diet and exercise for a prolonged period already get good results. The problem is that very few pts make the changes and/or stick to them. So if they can't follow more modest suggestions like "reduce soda and juice" or "eat more vegetables and less processed sugar," why would they be able to follow an extreme fasting regimen?

I also wouldn't expect the "excellent adherence" seen in the fasting trial of cancer pts to generalize to non-cancer pts. That group was probably self-selecting. Also, getting a cancer diagnoses (even one with an excellent prognosis) often scares patients into making extreme changes in a way that DM or CVD usually does not.