This is similar to an approach in a clinic run in Toronto by Jason Fung that puts patients on a Keto diet for a few days before they begin fasting for five days.

If I recall correctly, the purpose is to acclimate the body to running on ketones. Most of the patients are poor and live in “food deserts”, so they are encouraged to eat as much eggs and bacon as they want (with avocado, if it can be found.) The process is described by Megan Ramos in a 2018 podcast [0].

The science on fasting is sparse (but improving) and anecdotal evidence is common in health discussions. Fasting is divisive because it works great for some and is a non-starter for others. I’m sure that the Keto-before-fasting approach could be great for some and difficult for others, but we just don’t have the research to give us the hard numbers.

[0] https://podcasts.google.com/?feed=aHR0cHM6Ly9kaWV0ZG9jdG9ycG...

We also know that Ketogenic diets are not particularly healthy via promotion of consuming high quantities of unhealthy fats [0].

[0] https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-...

There are downsides to any diet. Keto has the huge upside of cutting out nutrient-poor highly processed foods that many people do not even realize are unhealthy.

Also, the idea of “unhealthy fats” is debatable [0], but that is besides the point: the largest downside to Keto is restricting a moderate amount of carbs from healthy choices, from your citation:

> meeting the diet's requirements means cutting out many healthy foods, making it difficult to meet your micronutrient needs.

[0] https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-mi...

Leaning in on old data and recommending people eat copious amounts of saturated fats is just as poor a diet choice as highly processed foods. [0]

[0] https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...