Fasting for one day is not physically or mentally
unbearable or unendurable, and doesn't cause major health problems for most people, which is why most major religions include
fasting as part of their
seasonal duties.
The guy/girl was feeling weak after
one day of
fasting.
Fasting for one day is not
unbearable, just about anybody, if not anybody can do it. Some people would be glad if fasting was something they did by choice instead of because they have nothing to eat.