断続的な断食

Lory

I don't think it has a mandatory age
But it is best not to do it while still being very young, while still developing. 
Not for kids and not for old people, cause they might be weakened by various affections

Jamie Gray

I don't think there is an age limit but should do at appropriate age.

Jenifer Rubio

IF is not for everyone. You should consult your healthcare provider  to ensure it is safe for you, especially if you have underlying condition.

Rocco Grassadonia

Meglio consultarsi con un medico.

Joyce Ho

I start at 30, and I drink water all the day