People who know me know that I have a deep interest in nutrition and diet strategies. I am also a big proponent of self-experimentation. Over the next several months I will be releasing several blog posts that examine different strategies for diet and their benefits and drawbacks. For some reason people have it in their minds that there must be one true “healthiest diet,” when in fact different nutritional strategies are necessary for different health conditions, different times of our lives, various health goals, and even different seasons! But, today we are going to examine the simplest of strategies: not eating! To quote Bruce Lee from Enter the Dragon (yes, I’m a fan) it’s “the art of fighting without fighting,” or dieting without dieting. For thousands of years healers have respected the power of fasting and now modern medicine is rediscovering its therapeutic benefit. There are many types of fasts, water fast, compressed eating window, 5:2, alternate day fasting, extended fasting, etc. They all have their pros and cons. I’d encourage you to research these different approaches, as the best type of fasting is the one that meets your goals and fits with your lifestyle. I have experimented with several. So, let’s look at who should be fasting, some common myths, different strategies, and then a little about my personal experience (hint: I’m currently on day 5 of a fast!). I wanted to add that this blog post is completely inspired by the terrific work of Dr. Jason Fung in reversing diabetes, insulin resistance, and obesity. His new book “The Complete Guide to Fasting” is an absolute must for anybody interested in this intense therapy and I’ll be linking to some of his lectures at the end of this post.
According to a study recently published in JAMA 50% of Americans are either prediabetic or diabetic. This health crisis is costing an estimated $245 billion dollars a year to our healthcare system. Over two thirds of Americans are overweight or obese. It is unsustainable. Yet, the same advice is given to all of these people: eat less and move more. And if it doesn’t work then I guess the problem is that you are a weak person with no will power. The rise of obesity and diabetes and the failure of medicine to address it deserves its own blog post, so I’ll try to avoid a rant. But, to best understand the benefit of fasting it is important to understand the two compartment theory of energy storage. I promise this is the only physiology I’ll cram down your throat! The two compartment theory basically states that the body has two separate ways of storing excess energy. The first, glycogen, is the easily burned sugar stored in the muscles and liver. This is quick and easy fuel for the body and great for high intensity activity like running away from attacking tigers (an activity I hope you don’t do much). The second storage is, of course, fat. Fat can be thought of as long term storage. It is the energy the body expects to burn when winter or famine arises. This ability for the body to store energy in two separate ways probably worked great for millions of years until the rise of the modern food industry. That famine our body was counting on never happens anymore! What controls which compartment we draw energy from is the the hormone insulin and, to a lesser degree, cortisol. As we all probably know insulin rises in the presence of glucose. If Insulin is consistently high the body adapts to its constant signalling and we become “insulin resistant.” Once we are insulin resistant and our constant insulin signalling is too high our bodies can no longer access the fat stores. Thus, a few pounds creep on to us year by year and it seems to get harder and harder to lose weight. So how do we break this insulin resistance and get insulin to drop back to normal levels. You guessed it! Fasting!
A few quick myths to debunk before we go further. People are often worried that hunger will overwhelm them on a fast. Hunger is the response to a hormonal signaling, mainly ghrelin, when the body is not getting expected food and is worried about running out of energy. Once insulin drops and the fat stores are released hunger subsides to a very manageable level. People are also concerned that they are going to slow their metabolism down. This is also a myth. If you want to slow your metabolism down consistently eat a high-carb low-calorie diet! When we fast our body significantly increases your resting metabolic rate and cortisol and norepinephrine rise. It is a survival response that is basically saying get off your ass and find food! Mental clarity also increases because we need to be more clever to find food. But, aren’t we going to lose muscle? Why would our body break down its muscle when it has all this lovely fat it has been storing? After a day or so there is a massive upsurge of HGH (human growth hormone), which protects our lean muscle mass. This HGH surge is a hack that bodybuilders have employed for ages! What is not good for our bodies is having insulin still stimulated, but inadequate calories coming in. The body is unable to unlock its fat stores due to stimulated insulin and the food energy is not enough, so there is no other choice but to slow the metabolic rate. This is what happened to the poor contestants on The Biggest Loser.
Now let’s talk benefits! For one there is weight loss. With the metabolic rate preserved and actually raised some our body freely uses the fat on our body for its energy needs. We are basically on a low carb high fat diet when we fast. We are just eating the fat on our bodies! By burning this fat the body enters a state called ketosis, meaning it is burning ketones for fuel. Ketones are considered a super fuel for the brain and we often experience heightened cognition. Maybe the ancient Greeks were onto something when they would fast to heighten their intellectual prowess… Burning fat for fuel instead of glucose also produces far less oxidative stress on our cells and inflammation dramatically drops in the body. Stubborn aches and pains often heal and our complexion often clears up. Another extremely interesting benefit is something called autophagy, which literally means self eating. This is the process by which the body scrounges and recycles all the damaged tissues of the body. This appears to have a strong anti-aging effect and there is some extremely interesting research on autophagy and cancer prevention.
Ok, so from a scientific and Functional Medicine standpoint the benefits seem pretty clear, but what about through the lens of Chinese medicine? Surely, a pragmatic medical system with over 2000 years of clinical usage has an opinion. Much of Chinese medical theory came out of Taoism, which is the study of natural cycles. Since feast and famine is a natural cycle of all creatures in nature, fasting was recognized for its health benefits. The Taoist recognized two forms of fasting, complete fasting for increasing mental clarity and health, and interestingly, abstaining from grains. But, we have to keep in mind that for much of the history of Chinese medicine’s development over-eating was not much of a problem. In fact, the only place we find information on a patient base that is similar to the average American is in the medical texts written specifically for the Emperor and his Court. These guys knew how to feast! This is a fascinating part of Chinese medicine that I will save for another post!
But, as with any eating strategy, it is not right for everybody. Who should avoid it? Let’s start with the obvious: pregnant or breastfeeding women, teenagers, and children. People with really low body fat should probably not do extended fasts. Those on blood pressure or blood sugar medication need to be carefully monitored by their physician. Fasting is one of the quickest ways to heal the body from diabetes or hypertension, but the medications really need to be monitored. Finally, those who have dysregulated cortisol output. Fasting is a stress on the body and significantly affects cortisol. Cortisol is a glucocorticosteroid, meaning one of its effects is on blood sugar management. I hate to use the term “adrenal fatigue,” because it does not reflect what is physiologically happening. But, many people use this term when they mean dysregulation of the hypothalamus – pituitary – adrenal axis (HPA axis). If your cortisol output or rhythm is significantly disrupted fasting will make you feel worse and cause further disruption. Clinically, I don’t use intensive tools like fasting until I have done a salivary or urinary adrenal output test. Basically, if you are under significant stress in your life or feel generally unwell some simple testing should probably be performed before any extended fasting.
As of writing this blog post I am currently on day 5 of a fast. So, what did I experience? I felt the expected hunger on day 1 and had a little trouble sleeping the first night because I was hungry. By about noon of day 2 the hunger had largely subsided and would come in intermittent waves that were easy to ride out. I am following Dr. Jason Fung’s protocol, so I am consuming broth, water, tea, and coffee. I actually had to ditch the coffee on day 3 because I found it was triggering some acid reflux. On day 3 I began to experience a really profound sense of calm. All background buzziness or low grade anxiety that often accompanies our busy day to day existence seemed to disappear. I felt more mental focus and felt more attentive. I was measuring my ketone levels with a breath analyzer and these benefits all seemed to occur when my body fully adjusted to burning fat as fuel. I dropped about 8 lbs, half of which was probably water. The overall experience was much easier than I anticipated. In general, my hunger was minimal, maybe 2 out of 10 with an occasional brief wave of intensity. My energy level overall was superb. I do my usual 3.5 mile walks every day and felt mildly euphoric. In my next go-around I’d like to experiment with hitting the weights hard to see if I can take advantage of the HGH surge. The calm, focus, and improved mood make me want to run an experiment with the ketogenic diet to see if those benefits were from my brain’s use of ketones for fuel or something else unique to fasting.
If fasting is so great why don’t we hear about it all the time? Well, actually a large portion of the world’s population does regularly fast for religious, spiritual, or cultural reasons. Also, not to be too cynical, but nobody makes money on fasting. I don’t have any magic fasting supplements to sell you or Chinese herbs that are required. It is fundamentally the action of not putting anything in our bodies. If the pharmaceutical industry could come up with a pill that could lower insulin, reduce inflammation, surge HGH, reverse diabetes, increase cognition, and burn fat we would see a commercial for it every five minutes on the TV! We actually save money when we fast. It’s the cheapest and most convenient diet ever! And I do say “diet” because, once again, we are eating. We’re just not putting food in our mouths.
So, remember, fasting can be as easy as not snacking after dinner and therefore having a fast from about 7pm until about 7am. This is an eating pattern that pretty much everybody in this country used to do a generation ago when obesity rates were magnitudes lower than now! Or you can experiment with any of the more intensive fasting strategies. But, please, if you are on any significant medications consult with your prescribing doctor first. If you are concerned about whether fasting may impact your already overwhelmed stress response then please contact our office for a consult and some simple testing. Everybody can (and already does) fast, so I encourage you to explore its health benefits. But, remember, if you are fasting and feel unwell then something is wrong! Just eat something. Then call someone qualified and do some troubleshooting. For more information I recommend Dr. Jason Fung’s new book The Complete Guide to Fasting. You can also find many fascinating lectures by Dr. Fung on youtube. Thanks for the inspiration, Dr. Fung. You are doing a lot of people a lot of good!