Fasting has been a part of life for centuries. People have historically undertaken fasts at different times of the year or at certain phases of their lives, usually for religious purposes. It has traditionally been used for cleansing and purifying in preparation for an important holy day, such as during Lent, Ramadan, and Yom Kippur. Famously, yogis seeking enlightenment fasted for days while meditating. Maybe you have experienced some of these types of fasts for enhanced spirituality, but are there health benefits to fasting as well?
Fasting has surprising health benefits and you don’t have to subsist on only water for days to reap the benefits. It is basically, like exercise, a good stressor for the body. Temporary good stress, as opposed to constant toxic stress, stimulates the body to improve how it functions and is good for you. During fasting, blood sugar stabilizes, insulin levels lower, and insulin resistance is improved, the digestive system uses the time off to clear itself out, damaged cells and debris are removed, excess body fat is lost, hormones thought to promote cancer are reduced, longevity is increased, and brain function is improved (1)(2)(3). All of that from going a few extra hours without food.
I fast every day, and hopefully, you do, too. The time between when you have your last bite of food at night and when you break your fast at (ahem) breakfast is, technically, a fast. I am not going to recommend juice cleanses, water fasts, or long-term severe calorie restriction. Some people have found benefit in these, but in my experience, they are incredibly difficult and not sustainable. The type of fasting I subscribe to is called Intermittent Fasting.
How fasting works to improve health is actually pretty simple. Your body needs a break. Every bite of food we consume is a whole body experience. Hormones, enzymes, peptides, and all sorts of other bodily functions are called to respond to even the smallest bite. When you constantly pack food in, even if it is healthy food in proper proportions, your body has to deal with it. Give it a rest! Your body simply doesn’t run optimally when it is fed every few hours (2)(4).
“The best of all medicines is resting and fasting.” -Benjamin Franklin
Intermittent Fasting respects the balance of nature. Everything in nature has a balance: Dark/light, day/night, hot/cold, positive/negative, sleep/wake. Using the same concept, there is a balance between eating and not eating. We spend so much time worrying about what we should eat, we lose sight of the fact that not eating is just as important. When you intermittently fast, you consume all of your calories within a certain time-frame and fast the rest of the time. How long you should go without eating is debatable. Ayurvedic practitioners recommend a 12-hour fast and 12-hour eating window (5). Those in ketogenic circles recommend longer fasts ranging from 13 to 18 to 24 hours. The right one for you is the one that you will do.
It sounds hard to go without food so long, but keep in mind that you will be asleep most of this time. For example, it’s pretty universally excepted advice to stop eating a few hours before bed. So, if you have your last bite at 7 pm, your breakfast can be 12 hours later, which is 7 am. Or, if you decide to do a 16-hour fast, stop eating at 7 pm, and don’t eat until lunchtime. What I usually do is stop eating a few hours before bed (this is the hardest part) and then I don’t eat until I’m hungry the next day. This normally means that I don’t eat until at least 10 am.
Why would you do such a crazy thing?
Health benefits of Intermittent Fasting:
- Blood sugar, insulin stabilization, and improved insulin resistance: If you’re not constantly eating, your blood sugar levels even out. When your blood sugar levels are steady, insulin levels remain steady as well, which over time lowers insulin resistance. This solves a whole host of problems including aging, cellular degeneration, adrenal function, and much more (1)(2)(4).
- Digestive system clean-up: Your small intestine loves to be clean. It likes to run through a self-cleaning process every day to stay healthy. In order for it to do so, it has to be empty and it takes several hours for all the food to move through after you eat. Additionally, the presence of food in the stomach stops this automatic cleaning function, possibly before it’s done (3). Rather than concerning yourself with detox programs to clean out your gut, may I suggest laying off the smoothies for 12 hours so it can detox itself?
- Boosted immunity: Can you imagine the number of pathogens present in your food? Especially if you eat raw food out at a restaurant (salad bar, eek!). Your immune system has to deal with these pathogens as well as those found on your shopping cart and in the air. Laying off the food for awhile allows your immune system to move on to other things, like cellular repair and fighting off the flu (2).
- Damaged cells are recycled, cellular debris is removed: When food is plentiful, cells get the signal to replicate quickly. During a fast, cells use the downtime clean up and repair damage or mistakes. This is vital for health. If damaged cells are allowed to replicate, these imperfections are copied along with the healthy information, which can lead to chronic disease and cancer (1)(2)(4).
- Excess body fat removed: Using the same feast and famine concept above, cells grow when there is plenty and clean up when there is little. The same goes for fat cells. Your fat cells will shrink when you fast. In one study, the only difference in the diets of two groups of people was that one fasted for 12-14 hours. Everything else in their diet remained the same. The people who fasted lost an average of 7 more pounds than the group that didn’t fast (2). One caveat you should keep in mind, however, is that enduring starvation diets for the sake of fat loss will work against you. Especially women. I am not talking about starving yourself for the sake of weight loss. There are many physical and psychological reasons for this that I don’t have the space for today, but please refer to the references below to learn why severe caloric restriction is a bad idea.
- Pro-cancer hormones are reduced: Specifically, IGF-1, pro-inflammatory cytokines, and certain other proteins that are thought to promote cancer are reduced or eliminated in people who intermittently fast. IGF-1 speeds cell growth and replication. Cancer cells have more receptors for IGF-1 than healthy cells, so limiting IGF-1 has the effect of slowing tumor growth (2).
- Longevity increased: I don’t know a single serious anti-aging expert or biohacker that doesn’t promote some form of intermittent fasting. Fasting promotes cellular clean up, increases human growth hormone, decreases free radical production, lengthens telomeres, inhibits the mTOR pathway (which is responsible for either growth or repair depending on whether it is stimulated or inhibited – you don’t want to grow, you want to repair), and reduces the risk of cancer (1)(2)(4). If you want to live a long time and look good doing it, fasting is your friend.
- Brain function improved: If you want to live a long time, you want your brain to function well into old age. Since fasting has such a positive effect on blood sugar, the risk of Alzheimer’s disease (now called Diabetes Type 3 in some circles) is greatly reduced (2). Fasting also improves myelination and reduces inflammation which decreases depression and brain fog (1). Plus, the cellular clean up effect we talked about above also happens in the brain!
The Metabolism Paradox
Do you believe that breakfast is the most important meal of the day and skipping breakfast will wreck your metabolism? Yeah, I thought that, too. As it turns out, this wasn’t the case for me, and there is pretty substantial evidence that it doesn’t happen for most people (1)(2)(4). In fact, the rate of metabolism can actually be increased through fasting (2). Training your body to burn fat will help in this area (1)(2), which we will talk about another day. You won’t be hungry if your body is able to burn fat stores during fasting. The best way is to give it a try and see how it works for you. Refer to some of the references below to read more on the subject so you can give intermittent fasting a fair trial.
Many people like to fat-fast as opposed to water-fasting. It has been known for awhile that you can reap the benefits of water-only fasting without the gnawing hunger, unpleasant side effects, and feelings of deprivation by consuming fat. Basically, carbohydrates and protein are the only things that activate these processes, so consuming carbohydrates and protein will break your fast. But fat does not. The benefits of fasting can still be had as long as carbohydrates and protein are not present. In order to explain why I would have to get into the mTOR pathway, insulin, leptin, and IGF-1, and I’m not going to go into all of that here. You can, and should, read about these things in the reference section (1)(2)(4).
So, we are not talking about metabolism-crushing calorie restriction. We are just changing where the calories come from. Hence, the hot buttered lattes such as Bulletproof Coffee have become popular. Fat fasting is also a better option for women (6).
The Fine Print
There are some contraindications for intermittent fasting that should be mentioned. If you are pregnant or nursing, do not fast. Likewise, if you have adrenal fatigue, kidney disease, or cortisol dysregulation it is recommended that these issues be resolved before attempting a fasting regimen, and then fasting should be supervised by a professional (2). Anyone with an eating disorder should avoid fasting as it can be taken too far. Likewise, if you are underweight or trying to gain weight, fasting is probably not your best strategy. Hypoglycemia can result if fasting is taken to the extreme, if you are not accustomed to burning fat for fuel, or if underlying conditions are present. Monitor your blood glucose carefully at first and watch out for signs of light-headedness, shakiness, pins and needles sensation in fingertips, or fainting. Use common sense and consult your doctor if you are on any medications or have conditions which are under supervision.
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