I’m not talking about intermittent fasting for several hours a day, since I’ve seen people jostle each other in all kinds of junk food during the hours when they allow themselves to eat. – AM, Scottsdale, Arizona

Dear AM: Fasting, the voluntary abstention from food, has been around as long as we have been. The conscious choice to abstain from eating can be a sacred practice, often linked to ancient religious beliefs that fasting can help cleanse the soul or spirit. When forced to function without an external source of nutrients or energy, our body must exist thanks to the materials at its disposal. We are designed to face this event, but there are limits.

A suggested benefit of fasting is its ability to provide a physical and mental break in our habits, especially the habits we want to change. The break offered by fasting can ease a transition to a better path – at least, that’s how it might work in theory. But there are other aspects to consider.

About 10% of food energy is used to digest, absorb and metabolize the contents of food. One of the claimed benefits of detox fasting is the removal of toxins that are responsible for a lack of vitality, which is a questionable construction. Does fasting, allowing the digestive system to rest, redirect energy to cleanse toxins and rebuild health? Not a lot of logic here.