system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why would a week "water fast" drinking only water, and only taking vitamins be detrimental to someones health?
gpt
Because the human body needs macronutrients as well as vitamins.  Fats, proteins, carbohydrates, fatty acids.

Also fiber.

So going without these things for an extended period is typically detrimental to one's health.