One of the reasons we fast is to cleanse our body and mind. If you think about from a scientific perspective, we are also cleansing ourselves of old cells through autophagy and fat oxidation. Since fat cells are so stubborn, some are literally stored away for years, this is significant. If we want to renew and revitalize our whole body, than it is a necessity, whether obese or healthy weight. Intermittent fasting should be considered hygienic, like brushing your teeth.
This article is reassuring:
Alternate-day fasting in nonobese subjects