True Life, Energy, Intermittent Fasting, Nutritional Healing, Functional Medicine

Intermittent Fasting: How it Energizes My True Life

Intermittent fasting has become a routine part of my personal daily energy support strategy. It’s simple, painless, and meets my number one requirement for self-care practices I stick with: it fortifies me for living my best life–my True Life. Isn’t that what good health is all about? In this article I’ll discuss what Intermittent Fasting is NOT (I sense your fear!) as well as what it is. And we’ll explore easy ways to make this profoundly healthy habit a part of your daily life.

Many of you have heard me tell the story of my midlife energy “smackdown,” when I crashed and burned at the ripe age of thirty-five, jumpstarting my  journey of using Functional Medicine and nutritional principles to heal myself and create vital energy.

I did it all to myself. After years of vegetarianism, low fat eating (the great baby boomer food fallacy), long-distance running, high stress and low play (think medical school, residency, on-call every third night, baby’s…yikes), I skidded into a great energy sink shortly after my second son was born. I was toast. Bone tired. Flattened. I was exhausted, depressed, sore, headachy, and dang irritable. The exuberant girl’s fire was out.

Happily, I healed. And I’ve since taken my personal self-care energy resilience strategy very seriously. Food plays a foundational role and Intermittent Fasting, a more recent addition to my food playground, has taken me to new heights–I feel lighter, happier, and have more sustainable energy. Priceless. A True Life.

Intermittent Fasting is NOT Prolonged Fasting

If you’re worried about prolonged periods of food deprivation–which you should be–Intermittent Fasting is NOT about going days with no food. In fact, I think prolonged fasting is unnecessary and potentially very dangerous. We may have enough carbon atoms stored away in our bodies to sustain a prolonged fast (think sugars and fats), but the proteins we need constantly to drive all the business of our bodies must be harvested from our muscles. Critical nutrients are shunted out of many key areas of our bodies–including our brains–to support those processes most necessary to keep us alive. These inevitable internal events that occur with prolonged fasting will always lead to nutrient depletion and for many, disaster.

What Intermittent Fasting Is

Intermittent Fasting is really a misnomer when thinking about the common parlance of “fasting” as prolonged periods of not eating. But in reality, Intermittent Fasting is not a prolonged fast. Technically speaking, we fast as we sleep overnight. We fast between meals. We fast whenever we’re not eating. Most of us go periods of many hours without eating–this is fasting.

With Intermittent Fasting, as it is commonly done, we extend the overnight fasting period and shorten the interval during the day when we eat.

I have done this by prolonging my overnight fast from my previous ten to twelve hours, to my current seventeen to eighteen hours. Then I have just two meals within the remaining six to eight hours of my day. I’ve discovered some good hacks for making this painless, as I’ll go into in just a bit.

The Benefits of Intermittent Fasting

I started experimenting with Intermittent Fasting about two years ago as a way to create more energy, resilience, and mental clarity for myself and to learn more about it for my clients who I thought would benefit from it. There are interesting tidbits of science as well as a wealth of anecdotal “data” that suggest promising potential health benefits.

While there is much work needed to nail down the relationship between intermittent fasting and good health, much of what we do know comes from studies done on animals. Intermittent Fasting, as with any food and eating strategy, is hard to study in humans because there are so many variables involved. Is Intermittent Fasting good for us because it reduces calories? Because we benefit from what we don’t eat? Because those of us who do it are healthier to begin with and care about living a healthy lifestyle? See, it’s murky. So what I glean from the science are suggestions about how it may benefit us, not solid facts.

Intermittent Fasting benefits our bodies by:

  • Reducing our intake of common food irritants and toxins: sugar, high fructose corn syrup, food allergens, high caloric-low nutrient density processed foods, food-laden pesticides.
  • Improving energy production in our bodies: through changes in the expression of genes that are involved in mitochondrial energy production.
  • Reducing inflammation.
  • Helping us shift metabolically from using sugars to fats for making energy (a processes we call, “ketosis,” a cleaner, more efficient way to make energy).
  • Reducing our overall caloric intake.
  • Reducing the damage to our cells and tissues by oxidative stress (induced by eating).
  • Protecting our brains (increases levels of Brain-Derived Neurotropic Factor (BDNF), known to protect stressed brain cells; increased removal of damaging proteins and debris that are associated with dementia and neurodegenerative disease).
  • Reducing blood sugar and insulin levels, and increased sensitivity of cells to insulin.
  • Fat loss leading to reduced obesity-related health problems.

As a physician and scientist I’m fascinated by the effects of Intermittent Fasting on our biology. Heck yes, I want to be as healthy as possible, improve my physiological resilience, and prolong my life.

But what’s most important to me–and probably more relatable to you as well–is how it makes me feel–what it does for me in my real everyday life.

In the end, I don’t practice Intermittent Fasting for its health benefits. I’ve adopted Intermittent Fasting as a lifestyle because it supports what I care about: energy, mental clarity, resilience, curiosity, awe, joy, creativity, playfulness, passion, open-heartedness, fire in my belly–all the attributes of my life that make it worth living and that are harder to come by when energy is low. At the end of the day it’s Big Energy that we all care about–to support a True Life.

My bottom line is this: the food we eat–and don’t eat–is the foundational fuel we need to support that Big Energy. For me, that’s what Intermittent Fasting helps me do.

Intermittent Fasting Benefits Our Lives By:

  • Making it more convenient–one less meal to worry about!
  • Ramping up energy for those things in life we care about.
  • Clearing the mind for better focus, less distraction, more creativity.
  • Improving exercise tolerance–once we’re adapted to it, we’re more fuel efficient.
  • Reducing digestive stress.
  • Making us more disease resilient–inflammatory disorders, blood sugar problems, neurodegenerative diseases.

How to Prepare for Intermittent Fasting

Should you just jump into it? I think it depends on what your current eating strategy is.

Could it hurt you? No–done right, you’re not depriving yourself of important nutrients or calories–this is not a calorie restricting food plan. You will not be starving.

But if your current diet is high in grains, sugars, and refined carbohydrates your metabolism will be highly adapted to using sugar for energy production. When you remove that sugar for a prolonged period of time–even just a few hours–the drop in blood sugar that occurs may set off an uncomfortable alarm response–stress hormones like adrenaline, designed to ramp up sugar availability by signaling the liver to make more, may make you feel uncomfortable (shaky, anxious, irritable, starving) so you seek sources of sugar.

If that sounds like you, you’ll need to prep your body first, something you should be doing anyway to get away from the long-term ravages and short-term blah of a high sugar and carbohydrate diet. Your body will shift from sugar to fat as its main source of energy as you change how you eat. Here’s what I suggest:

  • For two to four weeks, take out all grains (they are digested quickly into sugars–even “healthy” whole grains), refined and processed foods, and all obvious sources of sugar.
  • During this time, continue to eat your three meals per day, and include healthy proteins, plenty of fat (you will not go hungry), and a wide variety of plants.
  • At the end of this period, begin to lengthen the time between your last meal of the day and your first meal the next day. You can do this gradually, or in large jumps.
  • Make sure you stay well hydrated (at least 3-4 quarts of non-caffeinated liquid per day) and well rested during this time.
  • As your metabolism shifts to using fat to make energy, you may feel more tired. Hang in there–this will pass shortly, and will be worth it!

This is not a ketogenic diet, though many may choose to take that challenge on. For our purposes I am suggesting a shift away from common sugar sources but we are not restricting your total daily carbohydrate intake to levels sufficient to keep you in ketosis. For those who are interested in a ketogenic diet, there are excellent resources for this–you will be tracking your carbohydrate grams and likely restricting them to under 30-50 grams of net carbs per day.

My Intermittent Fasting Strategy

After much experimentation (food is my playground!), I’ve come up with an Intermittent Fasting strategy that works well for me and has been easy to incorporate into my life:

  • I eat my last meal of the day between 6 and 7 pm, depending on the day.
  • When I wake up in the morning, I drink 16 ounces of water right away and have 16 ounces of decaffeinated green tea (I use Sencha ground green tea for its exceptional antioxidant content) and put in about 2 tablespoons of coconut cream (this is the mostly fat-cream that separates out from the liquid in canned culinary coconut milk) and 1 tablespoon of MCT (medium-chain triglycerides) oil. These are fats that do not require digestion, are not stored as fat, do not create an insulin response, do not trigger an inflammatory response, and head straight to my mitochondria to support energy production. The added fat to my tea also staves off hunger and keeps me in ketosis throughout the day. This technically sustains the fast as it bypasses all the problematic aspects of eating food.
  • When I eat my first meal varies depending on my day, but typically occurs between noon and 3 pm. I occasionally forget to eat when I’m super busy or lost in an exciting creative project (like writing an article for you!).
  • I then eat two meals within that remaining six to eight hour window. One of them will be quite large. They both consist of healthy sources of protein and fat, and lots of plants.
  • I will occasionally add a tablespoon of MCT oil mid-day to amplify ketosis and soothe hunger that may arise.

Not every day is exactly like this, but this is pretty typical. I now find that if I do eat breakfast, which I did recently on a vacation, I’m okay because I don’t eat crap, but I don’t feel as light or vigorous. But that’s all okay. It’s not about being perfect, but resilient enough to still thrive when things don’t go just as we would like.

Your Intermittent Fasting strategy will not necessarily look just like mine. I’ve adopted it as a daily strategy but you might prefer to do it on an occasional basis. Be playful with this process. There’s no right way–just what serves you best.

Common Pitfalls for Beginners

  • Fear of being hungry: this is not a calorie restrictive diet and the use of fat during the “fasting” period staves off hunger.
  • Fear of not eating the usual and socially “prescribed” three meals per day: I can’t speak for everyone–we’re all different and have unique needs, after all–but the science and peoples’ experience suggests that we are more finely tuned energy and resilience machines when we eat less often.
  • Jumping straight from the “standard American diet” of high carbohydrates and processed foods into Intermittent Fasting: it’s better to allow our body to adapt from using only sugar to make energy to more use of fat to make energy–see above.
  • Missing the emotional benefits of eating more frequently: yes, we all use food for comfort, to numb out, and for sheer pleasure. I have found that my two meals per day are way more pleasurable–eating is a highly anticipated treat.
  • Trying to do too much too soon… baby steps might work best for you.
  • Trying to be “perfect” or to do it exactly as I do–it’s always an experiment and you’ll find what works best for you.

I invite you to give Intermittent Fasting a try and report back. For you pros out there, share your advice and experiences with us!


Karyn Shanks, MD. Healing Foods: My Favorite Healthy Fats. 2016.

Karyn Shanks, MD. Protein: How Much Do We Need to Support Optimal Health? 2016.

The Ultimate Start-Up Guide to the Ketogenic Diet. 2017.

Karyn Shanks MD


Karyn Shanks, MD, is a physician who lives and practices in Iowa City. Her work is inspired by the revolutionary science of Functional Medicine, body-mind wisdom, and the transformational journeys of thousands of clients over her twenty-eight year career. She believes that the bones of healing are in what we do for ourselves.

Leave a Reply

Your email address will not be published. Required fields are marked *