Not only is this fasting silliness based on zero science and basically pointless, it might just possibly be harmful. There are numerous organochlorine and organophosphate pesticides present at some level in the environment, which arguably might wound up in the food and water and be ingested and absorbed by the body. These chemicals are lipophilic, meaning that they get stored in body fat and stay there, inactive. As your fat reserves are normally turned over, some might get in the blood and your various organs might have chronic exposure to extremely low levels of these - likely too low to have any harmful effect. But if all of a sudden you go on a fast, you mobilize your fat reserves, and much more of these stored pesticides can be released at once, possibly reaching sufficient levels to have harmful effects.
Paracelsus said it a few centuries ago: it’s not the substance in itself that is toxic, it’s the dose. It’s a well-worn truism of toxicology that water is a lethal poison if you ingest too much of it.
Welcome to the SDMB, johnnyboy.
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The University of Nebraska Lincoln? The school can’t be that bad.