To cultivate and exploit our obsession with appearance, magazines sell air-brushed photos with ever new promises of a quick slim. Dietary supplements contribute to the more than half a trillion dollars Americans have spent in the weight loss industry in the last decade. Yet the yo-yo effect goes on and on—the weight goes up and down with little lasting benefit.

Jesus reminds us that what matters is what goes on in the heart. Matthew 6 begins with the warning: "Beware of practicing your piety before others in order to be seen by them; for then you have no reward from your Father in heaven." Then he warns about flamboyant almsgiving (6:2-4), showy praying (6:5), conspicuous fasting (6:16), and amassing treasures that become targets for robbers (6:19-20). The reason: "For where your treasure is, there your heart will be also" (6:21).

In the quest for popular spiritual "personalities," we are more likely to listen to an athlete or entertainer or politician with a dramatic conversion story than to a frumpy monk who has spent a whole life in quiet practices of prayer and inconspicuous fasting. In our own fasting efforts, we can impress people more with our sacrifice and devotion if we will at least look like we're suffering dramatically. But that external appearance of spiritual zeal guarantees nothing about what is going on in the heart. The poseur does not fast effectively.

The deep reward of fasting is not recognition by others, but a deeper experience of God's love. The faithful fast declares to ourselves and to God that the very thing that sustains us is God, not physical bread. The effective fast reminds us that living bread comes by God's graceful provision. True living bread does not come on our terms at our command. "Whenever you want it, as much as you want" may sound like modern marketing strategy, but remember that the original step of sin was made through one bite taken on our terms, rejecting God's terms of when and how much. An effective fast can reveal to us our inordinate hungers and dependencies. It can be like a spiritual full-length mirror before which we stand naked. In moments like that, we begin to see in much deeper ways how graciously God accepts and loves us.

We might wish that fasting, like many other self-improvement techniques, would be quick and dramatically obviously effective. There is no spiritual liposuction, and new research indicates that even physical liposuction, while it might reduce obvious belly fat quickly, has very little benefit for the heart. To benefit the physical heart, the fat must be eliminated through simple daily practices of eating less and working the muscles more. So it is in our heart of hearts.

May our fasting, along with all our spiritual practices, be increasingly more quiet, deep and effective for drawing our hearts closer to the heart of God.