Fasting: Is it Healthful?

Q: I’ve always thought that fasting was a religious thing, but lately I heard that it is now recommended for my health. So is it religious, a health thing, or both? How does fasting help me?

A: Fasting, a religious practice for ages, has also been a health practice for a very long time. To answer your questions with reasonable depth, we will address the physical health aspects now, and the psycho-spiritual aspects in a future column.

Fasting is the voluntary abstaining from all solid and liquid foods—except water(minimum of 2.6 quarts [2.5 liters] per day)—usually for a predetermined period of time. Water-only fasting has been employed by many around the globe for “cleansing” or “detoxifying” the body’s systems and as a metabolic and immunologic “jump starter” before making changes to new, healthier dietary practices.

Fasting may help prevent malignancies and increase the efficacy of cancer therapies. It may even reduce osteoporosis and autoimmune disease activity. Recent studies have shown that medically supervised, controlled water-only fasting for one week had beneficial effects on blood sugar control, blood lipid markers, body weight, and blood pressure.

Diets designed to mimic fasting taken by persons with diabetes and prediabetes for five days per month for three months reduced risk markers associated with aging, cardiovascular disease, diabetes, and cancer. People whose lifestyle includes periodic fasting may reverse early type 2 diabetes and hypertension, and may have better heart health than those who don’t.

During water-only fasting, stored carbohydrates are used up and fat is used instead (as ketones) for energy; age-damaged cells are recycled in a process called autophagy, or “self-eating”; and growth factors that promote development of healthy lean muscle, new brain cells, and renewed, active cells are released into the immune system. The use of ketones for energy favors the breakdown of fatty deposits in the liver and around internal organs and can produce favorable outcomes in metabolism.

Fasting may be a reasonable physical health-promoting practice in places where food is in abundance and overconsumption is common, but not where people are undernourished or malnourished. Pregnant women and those taking medications or who have an eating disorder, or serious medical conditions are cautioned against “just fasting.” Prudence, good judgment, and medical consultation and supervision are always in order. Yet what is eaten between fasts is still the major nutritional issue; a balanced, plant-based, nutritionally sound diet knows no substitute. An overall health-promoting lifestyle is key, and in some cases may be enhanced by careful, judicious, intermittent caloric restriction.

Peter N. Landless, a board-certified nuclear cardiologist, is director of the General Conference Health Ministries Department. Zeno L. Charles-Marcel, a board-certified internist, is an associate director of Adventist Health Ministries at the General Conference.