How do we judge the "popularity" of diets, outside of echo-chambers, websites or FB groups that support Keto, vegan, or carnivore?

I look at the popularity of podcasts. In the Health and Fitness top 50 rankings, The Huberman Lab is now #1 and there are no longer "keto" shows. Dr Huberman suggests a balanced, mixed diet.
https://forum.lowcarber.org/showpos...3&postcount=450. Dr. Peter Attia, Dr. Gabrielle Lyon, Max Lugavere, etc...their focus is on Health and Fitness, protein if anything, not keto or low fat.

Another way judge support for a diet is to rank Google searches. Keto has fallen steadily since Jan 2019, now only 14% interest from its previous high.
Or popular books in Health, Fitness and Dieting category on Amazon. #1 is Good Energy by Dr Casey Means it is focused on Nutrition

My echo-chamber is my own neighborhood, Health and Fitness focused, both retired and young families, and few are obese. It's not keto or vegan or Wegovy (at least I haven't noticed anyone melting away). Keto stopped working for me, my own poor metabolic health and lack of results were a way to judge various diet camps.

The article on Health.com reads like a massive Product Placement.
At least readers should know how much the drugs will cost them long term.