Pankaj Vij MD
Author, Turbo Metabolism: 8 Weeks to a New You
“I can think. I can wait. I can fast.”
“That’s everything.”
from Siddhartha by Herman Hesse
Odds are you’ve heard about intermittent fasting. Simply defined as “abstinence from eating,” it is something that humans have been doing originally out of necessity, and later as part of just about every religious or cultural tradition and for as long as we can look back at human history. Because of the way humans have evolved, our physiology is best suited to cycle between feast and famine and not well suited for a prolonged feasting phase (fed state). Lately, the potential medical benefits of intermittent fasting have increasingly been substantiated in animal and medical research projects and now extend to longevity, weight loss, improved metabolism (i.e., energy delivery to the cells), cancer treatment, and boosting brain power.
Based on my clinical experience, I often have my patients experiment with the idea of shrinking the eating window to roughly eight hours a day. This means restricting “feeding times” to eight hours within the 24-hour day, leaving the remaining 16 hours to digest and metabolize the food which was eaten. This allows time for the body to optimally extract and distribute the energy from the food. For example, the “feeding time” could open at 9 AM (yes, coffee or tea counts), and close at 5 PM, allowing the remaining hours for the body to be in a non-fed state. In the non-fed state, the insulin level can drop, allowing stored fat to be depleted as the body burns it for energy. Feeding and the subsequent process of energy extraction and delivery are stressors on the system and require a period of time (the non-fed state) before the next feeding cycle begins.
The best time to open the feeding the window is soon after waking up as insulin sensitivity is highest in the morning, meaning the body is most receptive to an energy bolus (a dose of energy) earlier in the day. Some people find it easy to skip breakfast and prefer to start the feeding window at 11 AM or even noon — and that works fine — but remember, the first sip of coffee or tea starts the timer!
There are two things we are looking for here. One is the duration of the feeding window (8 hours), and the other is the timing. Starting early takes advantage of our readiness to burn energy more efficiently earlier in the day. Insulin sensitivity is naturally higher earlier in the day and diminishes as the day progresses. Thus, eating a significant chunk of the food of the day before noon has distinct advantages. As Ruth Patterson, professor of family medicine and public health at the University of California, San Diego, points out: “There has been so much energy on what we eat and on carbohydrates, and it’s only very recently that there have been studies to say that we have been ignoring timing, and timing might be as important.”
Tweaking meal timing and frequency may be the hanging fruit in our quest for health, wellness, and longevity. While we can debate about the adage “You are what you eat” there is no doubt that when you eat can really make a huge difference.
