Isaiah 58 discuses what it means to fast.  The seventeenth century poet Robert Herrick summarizes Isaiah 58.  I’m retaining the Old English in which he wrote.  By the way Old English was not old in the 1600’s.  (Spell check is about to go crazy))

God Pleasing Fasting

The larder leane?

Is this a fast, to keep

And cleane

From fat of veales and sheep?

Is it to quit the dish

Of flesh, yet still

To fill

The platter high with fish?

Is it to faste an houre,

Or ragg’d to go,

Or show

A downcast look, and sowre?

No, ‘tis a fast, to dole

Thy sheaf of wheat

And meat

Unto a hungry soule.

It is to fast from strife,

From old debate,

And hate;

To circumcise thy life.

To shew a heart grief-rent;

To starve thy sin

Not bin;

And that’s to keep thy Lent.