DEAR DR. BLONZ: This is a follow-up question for the reader who asked about using diet drinks for a weight-loss "detox": Why not simply fast for a few days? Then you could avoid these expensive potions that deceive with their rapid loss of water weight.
I am not talking about intermittent fasting for several hours a day, since I have seen people shove in all kinds of junk during the hours they allow themselves to eat. -- A.M., Scottsdale, Arizona
DEAR A.M.: Fasting, the willful abstention from food, has been around as long as we have. The conscious choice to refrain from eating can be a sacred practice, often intertwined with ancient religious beliefs that fasting can help purify the soul or spirit. When forced to operate without an external source of nutrients or energy, our body must exist on the materials it has on hand. We are designed to cope with this event, but there are limits.
One suggested benefit to fasting is its ability to provide a physical and mental break in our habits, especially habits that we want to change. The break that fasting provides can facilitate a transition to a better way -- at least, that is how it might work in theory. But there are other aspects to consider.
About 10% of dietary energy is used to digest, absorb and metabolize what's in the food. One of the claimed benefits of detox fasting is the removal of toxins that are assigned the blame for a lack of vitality, which is a dubious construct. Does fasting, allowing the digestive system to rest, redirect energy to cleanse toxins and rebuild health? Not much logic here.
During the fast, our energy intake has stopped. Consciously, we might want more energy and attention focused on "cleaning house," but that's not how the body sees it. A constant, basic motivation is the need for sustenance. We might understand our fasting, but the unconscious controls are not in the loop.
Stopping all caloric intake to get more energy for detox would be like quitting your income-producing job to save the cost of commuting. There are better ways to gradually transition to a more healthful diet and lifestyle.
As for the toxins themselves, can fasting help the body shed these more effectively? Doubtful. Some substances the body seeks to eliminate are fat-soluble compounds, which distribute themselves throughout the stored fat in the body while waiting for elimination. Detox enzymes and systems are always working this problem, but please note that the more rapid mobilization of fat energy to fuel the body during a fast can result in increased blood levels of these unwanted substances as they also get released into the blood.
Finally, I invite you to check out the new reference book "The Building Blocks of Health" by Dr. J. Joseph Speidel, a public health physician and professor emeritus at the University of California at San Francisco. It covers an extensive range of topics, including cancer, dementia, weight loss and the pandemic. Especially worthwhile is the clarity with which Speidel explains the science of these issues. The book also includes a lifestyle checklist where all of us not-so-perfect individuals can get a sense of where we stand -- and what we might do about it. See b.link/45z2xv.
Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.