Chemnitz on the Final Purpose of Fasting

Fasting per se and on its own account is not worship of God.  But if fasting is joined to repentance and prayer, that is, if fasting is ordered to this end, that the flesh may be coerced, subjugated, and reduced to servitude, lest it contend against the spirit and hinder and disturb its actions either by its willfulness or its indifference, but that we have a body obedient and fit for spiritual things and for the performance of its duties, that the mind be admonished and become more fit for spiritual desires, so that the spirit may be able the more ardently and willingly to give and devote itself to repentance, prayer, and other exercises of piety, if fasting is practiced to this end, then finally it is pleasing to God. (Examination of the Council of Trent, Vol. 4, p 263-264)