There is no science to support the notion of detoxifying or cleansing[1]. Not eating does not cause your body to repair itself. There is no relationship between the time taken for digestion and your immune system. It's not like your body can only do one thing at a time.

By all means, if fasting makes you feel good or whatever then continue to do it. Just realise that none of your stated claims of its physical benefits are true.

[1] https://www.theguardian.com/lifeandstyle/2014/dec/05/detox-m...