Low Fat Is Out. Fasting Is In.


Like most Americans, I grew up eating during most of my waking hours. I typically began eating soon after rising and didn’t stop until shortly before retiring—some 15 hours later. That changed about four years ago.

In 2009 I learned about two key hormones: ghrelin and leptin. These hormones signal our body about whether to eat more, whether to store food as fat or burn it for energy. In addition, ghrelin and leptin affect our mood. I also learned we can manipulate ghrelin and leptin to our advantage based on what we eat and, importantly, when we eat.

For example: All things equal, when we stop eating four-plus hours before sleeping, minimize sugar and refined foods and include protein in our first meal, we will tend to store less fat at night, feel better and eat less. All that means more lean muscle mass; what most of us want. So, since 2009, I’ve practiced completing dinner by 7pm most nights and included significant protein (around 20-30 grams is ideal) with breakfast.

Incidentally, that also means restricting our food intake to a period of no more than 12 hours per day. The result is better sleep, a slight lean muscle mass increase and a pleasantly hungry feeling upon waking. (That was a new feeling for me).

So far, so good.

Enter fasting. Along with choosing unrefined foods, fasting is a way to program our bodies to be the lean, mean machines they were meant to be.

I often defer to our ancestors for wisdom about what and how to eat. Guess what? For most of human history, while there may have been food that could be gathered or hunted with some effort, there were no refrigerators full of food or supermarkets available 24/7. And at certain times of year, food may have been harder to come by. Our ancestors didn’t eat 15 hours a day, 365 days a year.

They probably ate more like wild animals eat. At times there was plenty of food and we’d eat. At other times there was no food so we’d live off our fat stores for hours or days—in other words, fast.

A growing body of research indicates that fasting offers several health benefits. These include reduced oxidative stress and aging, rest for the digestive system and organs and an increase in the production of human growth hormone. Fasting also programs our bodies to use body fat as fuel.

Fat is the primary fuel we evolved using for tens of thousands of years and we can store far more energy as fat than as glycogen. By contrast, today, virtually all of us use glycogen exclusively as fuel.

Finally, fasting (along with proper food choices) can manipulate ghrelin and leptin to work for us rather than against us, resulting in ideal body fat/muscle composition and stable mood.

And it turns out there are different ways to fast. Our friend Dr. Mercola offers a good overview of intermittent fasting, including his thoughts on Dr. Michael Mosley’s The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting.

In 2011 I did a five-day fast as part of a 30-day Blessed Herbs cleanse. In 2012 I wrote The Slow Fast during a six-day semi-fast (one raw, vegan shake per day) in preparation for a Gallbladder/Liver Flush. Now, in 2013, I’m playing with a form of fasting known as “compressed eating.”

Compressed eating involves restricting eating to between two and 10 hours a day (i.e., fasting for 14 to 22 hours per day) as a regular practice. For the past few weeks I’ve been eating during an 8-hour window each day. So I’ve come full circle: instead of eating 15 hours a day, I now fast 15-16 hours per day most days.

The result? After about three weeks I’m already noticing the aforementioned benefits. I’m able to eat plenty of food (including lots of good fats) and I’ve achieved a slight increase in lean muscle mass. I can actually feel my body switching from glycolysis (using stored glycogen as fuel) to ketogenisis (using stored fat as fuel) about 12 hours after my last meal.

My body is becoming fat-adapted, the way we evolved to be. And it’s very doable, becoming easier after a few weeks when your body adapts to using fat for fuel. Another piece of the epigenetics puzzle fits right in place.

If you do this (and I sincerely hope you will), I suggest increasing your fasting in 2-hour increments per week and eating healthy foods when you do eat. If you’re like me, one of the benefits of fasting will be that your cravings for unhealthy foods will become a thing of the past.

6 thoughts on “Low Fat Is Out. Fasting Is In.

  1. Angela Blessing

    Very interesting, Karsten! What about what I’ve always heard people say about the body storing fat or energy more than burning it when it perceives that there’s suddenly less food available? Have you heard that before as well?

    1. Karsten Post author

      Yes, it’s true that if we eat significantly fewer calories than necessary to maintain our bodies for more than a few days, we tend to go into “starvation mode,” which can slow metabolism among other negative side effects. Please note: Intermittent fasting (I.F.) does not involve caloric reduction yet it can have many benefits AS IF we were reducing calories — without negative side effects such as you mentioned. I.F. is either periodic or, if practiced regularly, it involves a compressed eating schedule/extended daily fasting period (different from reducing calories). Does that make sense?


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