Your body is composed of many hierarchical control systems. Some of them have feedback loops that imply minimum adaptation times longer than days. For a dietary related one (keto), one such adaptation is liver efficiency to produce fewer ketones + kidney efficiency to filter out uric acid. People who never have had gout but go on a keto diet sometimes get gout flareups because of a uric acid spike from the diet change, and it takes a number of weeks for uric acid levels to subside: https://www.virtahealth.com/blog/keto-adapted