IF As In Intermittent Fasting

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By: Amy Chang Radosevich, MA, ACSM, ACE, AFAA

As a follow up to last month’s post on Aging Like a Fine Wine, let’s explore the nutrition aspect a bit further. If you hang around gyms and studios, health food stores, or read any health related magazines, you can’t avoid coming across terms like Keto, Paleo, Whole30, Mediterranean, Carnivore, Plant Based etc. etc. All these terms typically have the word “diet” following them. Even though the term “diet” can simply mean the type of foods we habitually eat, many are conditioned to associate it with some form of food or caloric restriction for medical or weight loss purposes. We also tend to think of it as something we suffer through temporarily as a means to an end and that it’s unsustainable for the long term. As a fitness professional who is a firm believer of creating lasting change, I tend to raise a big red flag whenever I see diets that promises quick results and are highly time consuming in terms of preparation or overly restrictive. That’s why I’m a fan of the Mediterranean diet because it emphasize foods we should eat more of and foods that we should eat sparingly but nothing is totally off limits. Also, it focuses on improving longevity and prevention of chronic illnesses, rather than simply weight loss.

In addition to finding a well-balanced diet filled with wholesome foods, what else can we do to optimize our health? Does when and how often we eat matter? Researchers and proponents of a eating plan called Intermittent Fasting (IF) think it matters a ton. These researchers discovered that human bodies have evolved to live in sync with the Earth’s rotation, known as the circadian rhythm. This rhythm dictates when our bodies are most efficient at breaking down foods, when peak mental and physical performance occur, as well as when our bodies go into repair and regeneration mode. Living a lifestyle that matches our natural circadian rhythm is therefore highly encouraged and getting out of sync can have a negative impact on our mental and physical health.

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Researchers on circadian rhythm posits that obesity and obesity related illnesses were not a major issue until modern agriculture and technology created an abundance of food resources, where humans have access to anywhere anytime with little to no physical exertion required. We no longer have to be an early bird to get the worm. The snack and junk food industries certainly did a phenomenal job in conditioning us to eat in between meals, eat in front of the TV screen, movie theaters, social functions or any excuse we can find. We have progressively morphed into a species where eating is for pleasure, entertainment, coping with stress and boredom. Eating for longevity and health have become an afterthought.

All our mindless indulgences come with a hefty price. Physiologically, when we eat all day long, even if we don’t consume huge quantity of foods at once, our liver is constantly getting the signal to produce insulin to bring our blood glucose level back to normal. All the excess glucose is stored as fat. So we are basically training our bodies to be an excellent fat storing machine. Also, just like soldiers get put through vigorous and stressful training so they grow to be more resilient when it comes time to battle and defend themselves, the cells of our body also needs to be stressed to a certain extent so they too become more robust when we need them to fend off illnesses and injuries. Making sure our cells go through some period of starvation is one way of inducing that stress or training stimulus. When we feed ourselves or our “cells” all day long, they literally become content and lazy, leaving them unable to adapt and cope with more severe stressors and threats to our health.

The concept of IF first became prominent when researchers found remarkable differences in health outcomes between 2 groups of mice that were fed the same poor-quality and high fat diet. The group of mice ate whenever they wanted became overweight and diabetic, whereas the group of mice ate the same amount of food during an 8-hour window in sync with their circadian rhythm showed no signs of obesity or any precursors to diabetes. The time-restricted feeding group of mice even possess optimal body composition and improved motor coordination. A longer term follow-up study aimed to test the limit of the time-restricted window found that mice who were restricted to a 9- to 12-hour feeding window, along with weekend “cheats” where they were allowed to eat outside the optimal time, still remained lean and healthy. Even more promisingly, the group of mice who were unrestrained in the beginning of the study shed the extra weight after being switched over to the 9- to 12-hour window halfway through the study. This finding may potentially mean that obesity and related illnesses can be reversed by switching over to a time-restricted eating regimen.

All these results could be explained by our bodies’ natural circadian rhythm. Our insulin sensitivity is highest in the morning and early afternoon, therefore helping us metabolize and break down carbohydrates more efficiently. Enzymes that help break down cholesterol is also most present first thing in the morning. That’s why consuming most of our foods during the daylight hours is optimal.

During night time, after about 6 hours of non-feeding or fasting, our stored glucose, or glycogen is depleted so as to switch our bodies to a ketone, or fat dependent phase. This phase is critical not only because we are burning fat, but this is also when our bodies go into housekeeping mode and use a process called “autophagy” to remove toxins and damaged cells to counteract the negative effects of aging. This process is believed to peak after about 12 hours of non-feeding.

Based on the above concepts and research, here are some of the potential benefits of IF:

  • Aids weight loss
  • Increases energy
  • Promotes cellular repair and autophagy
  • Prevents Type 2 diabetes
  • Lowers bad cholesterol
  • Promotes longevity
  • Protects against Alzheimer’s and Parkinson’s
  • Improves brain function

Since IF’s goal is to mimic lifestyles of our ancestors pre-modern farming, it only makes sense that it can be accomplished in a multitude of ways. Afterall, it was often a feast or famine type situation. Here are some of the common IF methods:

  • 5:2 - Follow your regular eating schedule 5 days a week with 2 “fasting days,” where you only consume 500 to 600 calories.
  • 24 hour fast - No food for 24 hours once or twice a week (water, black coffee, tea allowed)
  • 16/8 - Consume your regular daily calorie intake in an 8-hour window

Depending on your lifestyle, you can choose one that you can actually adopt for the long term. Most people will find the 16/8 method most doable. In fact, there’s been research suggesting that people could benefit from even a 14/10 or 12/12 window so why not start with the 12/12 and go from there? Having a 7am to 7pm or 8am to 8pm window really shouldn’t cause much hardship for most. Simply eliminating late night snacking is a huge win for many.

Like any diet or exercise plans, it’s never a one size fits all. People on medications for diabetes, have a history of eating disorders like anorexia and bulimia, and pregnant or breastfeeding women should not try IF without physician approval or supervision.

For those of you who have tried or are currently practicing IF, share your experience and results with us in the comment section below!

Musician Moby once said, “I’m envious of people who can sleep as long as they want. I have the circadian rhythm of a farmer.” He might have gotten it right all along!