Matthew 5:17-18 tells us that when we fast, try to keep it a secret, so God who knows everything will reward us.
What Does it Mean? What is the motive of your heart when you make a sacrifice for the advancement of God Kingdom? Do you want people to notice and tell you how wonderful you are? If that is your motivation, you have got your reward. Your sacrifice will accomplish very little in God's kingdom. If you are really serious in your desire for God to do something, don't tell anyone what you are doing. It is between you and God. Use the time and energy you would normally spend preparing your food and eating to pray, talking to God about the burden of your heart, and strengthening your relationship with Him in the process. What would you like God to do? How badly do you want it? What sacrifice are you willing to make?