I think you're right on the money here. We just don't understand anything like a direct cause and effect between all the variables of personal gut biomes and ge

I think you're right on the money here. We just don't understand anything like a direct cause and effect between all the variables of personal gut biomes and genetics that create the metabolome. My n=1 experience has been that a fasting-mimicking diet where I emphasize low protein (especially BCAAs) for several days functions as a great reset after I refeed. I think if nothing else people may benefit from "jiggling the handle" metabolic fixes from temporary diet alterations, and various diets may push the microbiome, metabolism, and immune system to a more beneficial state, but that will look different for each person. I also think that starving out various gut bugs of certain nutrients like starches, protein, (yes, we know fat and carbs can be bad in excess. But too much protein isn't often talked about!) sugars, etc. will exert selective pressure on them. The ones that can cooperate with the body will gain over the ones that just extract easy nutrients. And of course, many things like antibiotics just blow away the whole ecology, like burning down a rainforest. It takes a long time to recover. I like to think of diet as a supply chain: if there's an excess of something, it's going to take cellular work to use it or put it somewhere else for later (e.g. fat, waste). If there's an overabundance of building blocks, the body will not be pushed to scavenge for those from old, broken down cell materials and they'll pile up. So changing the inputs up can give some pathways time to catch up. Fasting in general can also function in that way. The only problem is that it's kind of miserable to do, just like exercise.