Does intermittent fasting help lose weight? Is it a safe choice for diabetics?

When a patient says, “I am on an intermittent fasting diet regimen,” my mind goes to fasting as an ancient religious ritual wise men of the past, and its continuing practice in most religions. I am also reminded of a Hindi movie where the protagon goes on a punitive 30-day fast after committing a ‘sin’. Religious people remind me that the purpose of fasting is to strengthen the mind, detoxify the body and to add years to life. Looks too good, or maybe only some parts are good.
How does it work? Does it prolong life?
A fasted state rings physiological alarm bells to body systems. It sets in motion three important processes: maintenance and repair, consolidating security (stress responses) and switches on the “survival mode.” The body stops using sugar as fuel and instead starts consuming an acid called “ketone bodies.” When fasting is intermittent or prolonged but provision of essential nutrients is ensured, body systems become better protected and survival is enhanced. Studies in animals show that fasting prolongs life. Indeed, among so many potential options, this may be the only way to prolong life.

Unlike research in animals, whose lifespan is limited hence permitting survival studies, it is impossible to do so in humans. Hence, we look towards other benefits which could be studied over a short time; weight loss, decrease in blood sugar and so on. These processes have been studied using three fasting regimens, alternate day fasting, 5:2 fasting (2 days fasting in a week) and time restricted eating (8-18 hours daily fasting, akin to Ramadan fasting). Results are mostly good in human studies. Body weight, body fat, blood pressure and cholesterol decreases. Weight loss over 6-12 months ranges from 3-10 per cent. Patients with diabetes improve their blood glucose profile. Fat from organs gets dissolved, thus enabling better functional state. Finally, there is some experimental data to show that it may increase memory and delay onset of Alzheimer’s disease.
Is this for everybody?
The questions arise, should we leave traditional daily calorie restrictive eating (eating a low calorie diet daily without fasting in hours or days) and embrace intermittent fasting as an approach to weight loss and metabolic control? Could these fasting diets be integrated into the lifestyle of everybody? These are some of the unknowns that we are facing today. Most studies comparing fasting diets with calorie restrictive diets are of short duration (3-6 months). A few studies of one year duration show no difference between intermittent fasting regime and daily calorie restriction diets. Further, people are also not able to follow stricter regimen like alternate day fasting, and many dropouts are seen in studies.

Our fasting sages were very calm, composed and energetic, but that may not always be the case in those following intermittent fasting. Some people develop irritability, mood disorders, dizziness, fatigue and headache, especially during the early days of the diet regimen. Some patients with diabetes may have a surge of blood glucose in a non-fasting period because of unselected and high calorie consumption (“I can eat whatever I want during the non-fasting period”).
Why diabetics must be cautious
Patients with diabetes must also follow caution as they may have low sugar levels (‘hypoglycemia’), especially during fasting periods, and high sugar during non-fasting periods, thus majorly upsetting metabolic balance. Such ups and downs of blood sugar may weaken organ systems. Another important point: patients with diabetes taking SGLT2 inhibitor drugs (Empagliflozin, Canagliflozin and Dapagliflozin) may face particularly hazardous and acutely developing acidic body ailment (“ketoacidosis”). Finally, once you lose body fat with intermittent fasting, you may lose muscle too; and, become weaker! Hence you cannot learn intermittent fasting from the internet and have a go at it. Your hand must be held nutritions and physicians when you decide to walk this way.
If you want weight loss and good control in diabetes, blood pressure and lipids, traditional daily calorie restrictive diets and intermittent fasting diets both produce similar results. However, if you want a longer life and stop memory loss and brain degenerative diseases, intermittent fasting has positive potential, although no long-term human studies are available. So, what will it be? A long-term intermittent fasting? Probably only for a few who can follow it, and with uncertain benefits.
(The author is a Padmashree awardee and has written the book “Diabetes with Delight”)