This is confusing.

This research said fasting will kickstart your body's white blood cell to do their job.

On the other hand I read from another research your body will also perceive fasting as a sign that your body is in danger of starvation and then permanently increased your appetite level.

You'll get a new immune system while fasting but your body have been automatically set to eat even more food once you're out of fasting.

I thought there where pros and cons when you fast?

Say you starve yourself, you get to live longer by slowing down your metabolism but doing so means your at more risk for infection and susceptible to the flu and cold, speed up your metabolism, you age quicker but are more hardened to diseases and sickness?

I wonder if this is why food starts being unappealing when your sick, I know when I catch something food always looks and tastes awful. Maybe it's the bodies natural way of trying to fight off the infection with fasting?