Your Doctor's Thoughts On Intermittent Fasting
We hear a lot about fasting or intermittent fasting these days. Questions about fasting diets come up often in my practice. This and other supposedly “fad” diets are all over the media, but is this one truly a fad? I would argue that, no, it actually is not a fad. Fasting has been around since our early ancestors. Think about the early days of hunting and gathering. There would be long stretches of time between when these “cave men” and “cave women” would find his or her next meal, so our biology has developed with this way of eating. We also see fasting in many religions and spiritual practices. Additionally, the word breakfast, literally means to break a fast; we are technically fasting overnight every night. So, fasting is not a new concept, it is not just a fad, and you actually already do it to some extent.
So, what is the point of incorporating some type of fasting into your life? And, I do prefer to call it a lifestyle, or way of eating. I really don’t like the term diet. I’ll use it from time to time for brevity, but, any way of eating you adopt, should be just that, “a way of eating” or “a shift.” What you need at any given time can change.
What are the benefits?
The obvious one is weight loss or weight maintenance. The idea is not to count calories or cut calories, but just to eat in a narrower time window during the day, which, interestingly, has been shown to both help with weight loss if overweight and weight maintenance if already at a healthy weight. We also see a decrease in diabetes, blood pressure, and heart disease. This is partly a result of weight loss, but is also related directly to the fasting. It changes our biochemistry in a sense.
It can also heal the gut. By giving the digestive system a longer break, it allows the intestinal lining to heal. Leaky gut is something we talk about frequently in functional medicine, where essentially, your gut lining is inflamed to the point that the wrong stuff “leaks” through and can cause inflammation in your system: think aches, brain fog, allergies, fatigue. Fasting can be a useful tool in working on repairing leaky gut.
This next one is my favorite: There is a really fascinating process that starts kicking up at about 12-13 hours of fasting. It is called Autophagy, which literally means “self-eating.” We always have a low level of this going on in our cells, and the purpose of it is to clean things up. Even in a healthy body, we have damaged or broken cells that occur from normal metabolic processes. We have more damage with age, stress, or toxin exposure. If these old or damaged pieces build up, it leads to inflammation, which is involved in so many diseases. Fasting causes Autophagy to essentially “self eat” the damaged pieces and even recycle those pieces into new cells and new functions. Autophagy is an amazing tool to possibly prevent neurodegeneration, enhance the immune system, and may even have a role in preventing cancer or in the treatment of cancer. There are studies looking at the differences in giving chemotherapy to patients in a fasted state vs. non-fasted state, and the data is promising. In the fasted state the cells are essentially protecting themselves, since fasting triggers a sort of survival mode, and the white blood cells rebound much more quickly after chemotherapy. There are big things happening in this area of research.
On a lighter note, if that doesn’t all sound like reason enough to give it a try, it will also make you look good. The same processes that clean up your cells to prevent disease, are also going to have an anti-aging effect, and improve your skin, hair, and body composition.
How do you do it?
The term is used loosely, but the basic idea with intermittent fasting is that you are narrowing the window in which you are eating.
A common way to start is just using a 12 hour window, which may not be too different than what you already do. An example would be that you would have your dinner around 8pm and then just water until 8 am the next morning. Not so bad. You can work your way up to longer fasting periods as tolerated. A common one is the 16:8 method with a 16 hour fasting window and 8 hour eating window. So eat breakfast at 10 am and then the last meal of the day at 6 pm, or shift that however it works for your schedule. Ideally you are making healthy food choices within that window, but we are just focusing on the general timing guidelines today. Theoretically, you should not have to worry too much about what you are eating, for the intermittent fasting to still have benefits. But, if you can try to mostly eat real food and less processed food you will be off to a good start.
Some individuals will use a medium chain fatty acid like MCT oil added to their coffee in the morning to give their brain fuel, but still technically be in the fasted state until the first real meal. Otherwise, black coffee, or tea in the morning would be fine. Staying hydrated is key. Other than sipping on herbal tea and water during the fasting window, especially if doing a long fasting window, sipping on bone broth can help to keep you feeling good. It contains minerals, gelatin, and small amounts of protein, which often helps with hunger without eliminating the previously mentioned benefits. I have a homemade bone broth recipe a couple of blog posts ago, to get you started.
The 12-13 hour fasting window is where you will start to see that increase in autophagy, and some fat burning, and then around the 16 hour fasting window, those things increase and you may also see an increase in human growth hormone production. Growth hormone typically goes down with age, but if we can keep it in the normal range, it is very regenerative.
How do you know if this is for you?
You should feel more energy and have more mental clarity when you are intermittent fasting. If you feel sick, sluggish, weak, are getting headaches, or have brain fog, then this might not be for you. If you feel ill at all, you should stop. Some individuals that might not do well with fasting are those with a high level of unmanaged stress, have adrenal fatigue, or autoimmune issues. It might work for some, but not all. Use how you feel as a guide. I would not advise anyone with a history of disordered eating to try fasting, as it can trigger relapse. Those under 18 years old, and pregnant or nursing individuals also should not fast.
I don’t recommend doing any type of fasting without consulting your doctor, and especially if you want to go longer than 16 hours.
What happens after 16 hours?
There is research going on at the University of Southern California, lead by Dr. Valter Longo and they are looking at the effects of prolonged fasting. There is another process that occurs at 36 hours, which is stem cell regeneration. So we are not only cleaning up and recycling, but now actually repairing cells. This is such an important piece in prevention, longevity, and quality of life. The USC research is looking at what they call a fasting mimicking diet, which lasts for 5 days, but you are eating foods that keep your body almost tricked to act like it is in a fasted state. The research is exciting and promising.
I do regularly practice intermittent fasting myself. Not every day or even every week, but I incorporate it into my way of eating, and it does make me feel good. I eat a veggie heavy paleo diet, and enjoy gluten free treats from time to time. There are a few other ways to incorporate fasting, including the 24 hour fast, the 5:2 pattern, and more extended fasts. I encourage you to really look at what your own eating vs fasting window looks like and think about if intermittent fasting is something you could incorporate into your lifestyle. Talk to your doctor first before starting any type of intermittent fasting. If your doctor is not familiar, then come see me. :)