For oneself and decide whether anyone needs to fast.

אולי אתם לא רוצים להיות כסילים והולכים אחר החנפים

There are a myriad of reasons to fast or not to fast. Every case is different and both doctors and your local orthodox rabbi need to be consulted. You can not put 2 individualswitwith sane disease under the sane blablanket and tell them both to fast as the severity of the disease might be very different

And, of course, you shouldn't fast if you're an atheist. To do so would just be silly.

as long as you don't think you're impressing the Imaginary Friend with your ability to abstain from food for 24 hrs. - you're OK.
Even better, would be staying a "mensch" 24/7 for 365 days a year.... :-))

Remember, birth control pills are abortion pills!

Who do not fast on Yom Kippur? Secular Jews (Atheists)!

Reform Jews (Luke Warm Jews) fast on Yom Kippur like King Herod.

Orthodox Jews, of course, fast on Yom Kipper.