An acceptable fast

I was struck by this passage today. The prophet Isaiah is speaking for God about what is an acceptable and pleasing fast in God's eyes. I have always thought of fasting in terms of self denial and seeking a closer relationship with God. This passage gives me a whole new view of fasting; not one of denial but of service. I never did understand how my denying myself food would impress God. This passage tells me that what impresses God is selfless giving.
Isaiah 58.6 -9 (NKJV)

“ Is this not the fast that I have chosen:
To loose the bonds of wickedness,
To undo the heavy burdens,
To let the oppressed go free,
And that you break every yoke?
7 Is it not to share your bread with the hungry,
And that you bring to your house the poor who are cast out;
When you see the naked, that you cover him,
And not hide yourself from your own flesh?
8 Then your light shall break forth like the morning,
Your healing shall spring forth speedily,
And your righteousness shall go before you;
The glory of the LORD shall be your rear guard.
9 Then you shall call, and the LORD will answer;
You shall cry, and He will say, ‘Here I am.’