Evidence is emerging that when eating is confined to a 6-hour period, as in an 18
hours fast, metabolism switches from glucose supplied by the liver to adipose
cell-derived ketones for energy. Intermittent fasting is associated with health benefits,
including weight loss and decreased obesity. Studies in animals have found a
decreased incidence of obesity, cardiovascular disease, cancers, and brain diseases.
Studies in humans suggest that diets with a variety of fasting intervals can improve
the biomarkers that indicate good health and help weight loss.
Among weight loss eating strategies are those that incorporate “mini-fasts,” such
as alternate day caloric restriction or eating just one meal every 24 hours. Intermittent fasting at 18 hours a day or with food restricted to 500 to 700 calories every other day or two days a week (5:2 fasting) improves cholesterol and triglyceride
levels and decreases obesity, insulin resistance, high blood pressure, and inflammation.
Unfortunately, these fasting patterns bring about loss of lean body
(muscle) mass. Avoiding a total fast and taking in 500 to 700 calories a day of foods
that include carbohydrates can help preserve lean body mass. The evidence for the positive human health benefits of intermittent fasting has come mainly from short-term studies, but 5:2 fasting (with some food intake on the two
fast days), every other day fasting and eating only in a 6-hour period appears to
confer benefits to health including weight loss. Proponents of intermittent fasting
claim that the initial side effects of hunger and irritability during fast periods usually disappear after a month.
It should be noted that there is evidence that a total fast of more than one day is
unhealthy and intermittent fasting according to any schedule should only be done
under the supervision of a physician—especially if you are diabetic or on any medications.
My advice is to avoid long term total fasting, but some people may
be helped by the 5:2 partial fast or the 18-hour fast regimen. I think it is better to
adopt a healthy diet that leads to a stable, healthy weight without excess adiposity—
one that you can eat every day long-term.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel