Intermittent Fasting - It’s About More than Just Weight Loss
By: Colleen Rivers, MD
One of my favorite “jobs” as a physician is to respond to the many questions my friends and family have about the latest health trends. Very often, I must reluctantly report that there is no science behind the new fad, but as long as it isn’t harmful, feel free to carry on! In the case of intermittent fasting, however, I have been pleasantly surprised by the data and even more impressed by how this practice goes beyond weight loss and can improve important aspects of our physiology. First, let’s get our definitions straight. The research on intermittent fasting focuses on three common protocols. One is alternate day fasting and two is 5:2 fasting (meaning that a person eats normally five days per week and fasts for two nonconsecutive days.) In these cases, fasting days are defined by a severe reduction in calories (typically 500-750/ day.) The third protocol (and likely the easiest to implement) is time restricted feeding, meaning that a person only eats for a certain period every day (often eight hours), for example between 12 pm and 8 pm. This is also known as circadian fasting because it takes advantage of the hours we are sleeping to accrue fasting time and helps to reset our circadian rhythm on the cellular level.
It has always seemed obvious to me that one of these protocols could lead to weight loss because it puts some structure around our eating and facilitates cutting calories in those of us who tend to eat all day. However, it wasn’t until I looked at the research that I found the vast array of other benefits we gain from “flipping the switch” metabolically, and choosing to spend time in a fasted state. Most of us, by twelve hours after our last meal, run out of glucose stores and start breaking down fat for energy. In this process, we create “ketone bodies” which happen to have some incredible effects on the cellular level. They boost multiple pathways involved in cellular repair, reducing inflammation, and even increasing neuroplasticity (i.e; the ability to make new brain connections.) On a clinical level, people practicing intermittent fasting over the course of months have shown some impressive changes such as better insulin sensitivity, lower blood pressure and heart rate, and decreased abdominal fat. They also have improvements to their liver health and the diversity of bacteria in their microbiome. Anecdotally, people report having improved energy and focus, favorable results that I too have experienced!
So what is my point in presenting this data? That we should all immediately cut back our eating to an eight hour window every day? Of course not! The “perfect” manifestation of intermittent fasting might not be a great fit for all of us. (In fact, my ability consistently adhere to a sixteen hour fast varies with the ebbs and flows of my life.) However, I do hope that you will consider closing your kitchen at 8 pm and holding off on breakfast until 9 or 10am. If this is easy for you, then maybe you extend your fast by even a few minutes every day. Each minute that we spend fasting beyond twelve hours gives us the chance to reap some important benefits. My take on the current research is that this simple intervention has the potential to be a game changer in improving our metabolic health and possibly more. Remember, it’s the small habits of our daily lives that most determine our wellbeing. Let’s start focusing not just on what we eat, but on when we eat! It doesn’t have to be perfect. It just has to be moving in the right direction!
Disclaimer: Persons with a history of an eating disorder such as anorexia nervosa or bulimia or persons on certain medications for diabetes or who are pregnant or breastfeeding should not engage in intermittent fasting. Please consult your doctor before starting this practice.
References:
de Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease. N Engl J Med. 2019 Dec 26;381(26):2541-2551. doi: 10.1056/NEJMra1905136. Erratum in: N Engl J Med. 2020 Jan 16;382(3):298. Erratum in: N Engl J Med. 2020 Mar 5;382(10):978. PMID: 31881139.
Emily N C Manoogian, Lisa S Chow, Pam R Taub, Blandine Laferrère, Satchidananda Panda, Time-restricted Eating for the Prevention and Management of Metabolic Diseases, Endocrine Reviews, Volume 43, Issue 2, April 2022, Pages 405–436, https://doi.org/10.1210/endrev/bnab027
Dr. Colleen Rivers is the founder and CEO of Seek, a health and wellness platform that empowers people to take back ownership of their own health. Its overarching philology is that the act of seeking — or taking one small step toward your healthiest self — is in itself transformative. Visit her website: www.seektransformation.com