Ping Phil: Cats and fasting

Found this. How does it square with conventional wisdom that cats
should not go without food for more than a day or so?

http://www.felinefuture.com/nutrition/bpo_ch9.php

"Fasting
It is very beneficial for healthy adult cats, to withhold all food for
a 48hour period on occasions. This extended fast will enable the body
to clear some accumulated toxins from fat tissue, and completely empty
the bowl. Healthy cats don't fast voluntarily, but are frequently faced
with an involuntary fast in a natural setting through unavailability of
prey, or repeated unsuccessful hunts. They will, however, frequently
refuse food when unwell as a possible means to speed recovery. Cats are
unharmed by the absence of food for several days, and in extreme times
of famine may loose up to 50% of their body mass and still survive. It
is, however, critical that the cat has unrestricted access to fresh
water during fasting."