Healing Fast vs. Spiritual Fasting
In response to your question, it can be noted that therapeutic fasting and traditional Orthodox fasting pursue fundamentally different goals and objectives. Therapeutic fasting is primarily viewed as a method of physical cleansing and improving the condition of the body – a medical or dietary approach that often involves undergoing a course in a specialized facility and is based on purely rational grounds. As noted in one source, "So fasting is much better than a regular diet or therapeutic fasting. And notice, people pay a considerable amount of money to undergo a course of therapeutic fasting or body cleansing in a medical facility. Fasting, however, can be done completely free of charge – and you even save money on meat and dairy products" (source: link txt).
In contrast, traditional Orthodox fasting is purely spiritual in nature. Its primary goal is not to achieve improved physical condition or weight loss, but rather to engage in spiritual abstinence and self-sacrifice before God. The Orthodox understanding of fasting is aimed at achieving inner purity, overcoming personal weaknesses and sins, as well as attaining a closer communion with God. This is emphasized in the following statement: "The purpose of fasting is not to lose weight or improve one's physical condition, but to engage in spiritual abstinence and self-sacrifice for the sake of God. Fasting is pleasing and acceptable to the Lord as an outpouring of a soul striving for purity, seeking to cast off the chains of sin and free the spirit from the bondage of the flesh" (source: link txt).
Thus, the main difference lies in the fact that therapeutic fasting is targeted at treatment and physical cleansing, whereas Orthodox fasting serves as a means of spiritual renewal intended to lead one to inner harmony and a deeper communion with God. These two approaches differ fundamentally in their priorities and ultimate objectives.