Fasting is everywhere now. Everyone from your college professor to every celebrity is doing it. If we look past our natural reaction to constantly follow trends, you can see that fasting has a rich history in medicine and everyday life. Even though it seems like it came on in the last couple of years or so, fasting is a part of our history going back as far as the father of modern medicine, Hippocrates, who said, “To eat when you are sick, is to feed your illness.”.
For some, fasting can be a stressful, forced experience, for others it comes naturally. Some people really stress themselves out by not eating, and this can cause an inflammatory response and a rise of our fight or flight hormone, cortisol. The solution for these types might be as simple as shifting what time they are fasting, or doing fasts more sparingly. What is important to remember is that it is not a magic pill. Depending on the result you want to get out of it, the method may very. Lets go through some of the benefits and common ways to fast.
Weight loss is often the goal people have in mind when they begin the journey into fasting. When we go more than 12 hours without eating, our bodies natural digestion clock has ended. At this point we can tap into our bodies natural stores of energy (fat). This study showed that when eating 100% of energy needs in an 8 hour window (fasting for 16 hours), a reduction in fat mass and maintenance in lean body mass was achieved.
This is interesting, because usually studies focus on reducing calories to achieve weight loss. Eating less is easier for some people in a compressed window of eating, simply because they are not hungry enough in 8 hours to get the total amount of calories for 100% of energy needs. A lot of the time intermittent fasting leads to easy calorie restriction. This study found that whether constant, or intermittent, calorie restriction by 15% worked to lower fat mass and retain lean muscle mass.
Insulin Sensitivity and Type-2 Diabetes
Type-2 diabetes is an epidemic in our modern world. 9.4% of our population has Type-2 diabetes, with more than twice that diagnosed with pre-diabetes. This is a disease that can be prevented, and is caused by being resistant to insulin. Basically, our cells become so resistant to insulin that anything containing carbohydrate will pump up our blood glucose levels and exogenous insulin is needed to bring it in check.
A study was recently done examining the effects of early time-restricted eating (eating all calories within a window of time) on insulin response and inflammatory markors
- Pre-diabetic subjects were put in a 6 hour eating window from 8-2, and a 12 hour window from 8-8.
- The 6 hour window improved markers for insulin resistance, blood pressure, and oxidative stress.
- It reduced appetite in the evening, stimulating weight loss.
This is interesting because these changes happened regardless of weight loss, which has been assumed to be a primary factor in increasing our insulin sensitivity and combating Type-2 diabetes. This could be due to a couple different things. The stress hormone cortisol is present in the morning, and eating a large meal in the morning can help reduce it, bringing down appetite for the rest of the day. This could allow for an early small meal in the evening, allowing a 12-16 hour fast until breakfast depending on what time you eat. Fasting also lets us burn through our glycogen,(stored glucose in the muscles and liver), so that we can actually take in carbohydrates without being overloaded with a blood glucose spike that has nowhere to go if our glycogen stores are already full. I have a suspicion that fasting pairs optimally with a low carb diet, so that in a fasted state we can be burning our own fat for fuel efficiently because our body knows how. Even if you are already eating a low low-carb high-fat diet, insulin sensitivity can be improved by implementing fasting every once in a while.
Longevity and Chronic Disease
One of the main reasons that myself and my wife fast, are for the chronic disease management and longevity. After Beth’s diagnosis with cancer a few years ago we have been on a steady daily fast of 12-16 hours at least.
You can look at these two things, longevity and disease management, as the same. We all want to age in a healthy way. What most people die from as they get older is cancer, heart disease, or Alzheimer’s. If we can keep chronic disease at bay by taking a few steps to mitigate the risk of getting them, we can also age better and live longer.
Research is showing that fasting can be a potent measure to take. This is because when we fast, our mitochondria (the energy production centers of our cells) actually run much more efficiently. At around 16 hours, they begin a process known as autophagy. This is the cells way of repairing itself and actually using damaged organelles and mitochondria in the cell for energy. This promotes optimal mitochondria function, less oxidation, and less tissue damage. The end result being that if our mitochondria are utilizing energy correctly, there is less of a chance the cells will begin the metabolic pathways that lead to cancer growth.
Another effect of fasting is its up regulation of AMPK. AMPK is an enzyme that plays a role in maintaining energy homeostasis in our body. It also is crucial in the process of Fatty-acid oxidation. This is when fatty acids are liberated from our stored body fat and used as energy by our mitochondria. Interestingly, AMPK also plays a role in the prevention of cancer. When cells start to become dysfunctional as in the case of cancer, they primarily make energy through aerobic glycolysis. Simply put, they depend heavily on glucose for fuel. In this study, AMPK inhibited the process of aerobic glycolysis in tumor cells. If our cells aren’t using glucose as a primary energy source, they are using fatty acids as fuel, and that’s a good thing.
Fasting doesn’t have to be hard. Many people, (myself included) do daily fast of 12-20 hours. This may sound daunting, but in reality I find that it fits a workday schedule better than eating every couple of hours. On days I work in the morning, I generally don’t eat until 11 or 12. Then I eat again at around 6 or 7. This ends up being 2 meals a day, with around 16 hours between my last meal and the first meal the next day.
I really enjoy eating two large meals. It makes me put more thought into what I’m about to eat, because I want to make sure I’m getting all the nutrients I need in two sittings. Some people eat in the morning shortly after they wake up, and eat an early dinner around 4. I like this schedule when I have the day off.
An alternative is longer fasts of 24 or more hours once or twice a week, then eating normally the other days. The benefit of longer fasts is that things like autophagy and AMPK activation are boosted even more.
That’s it for this week everyone. I barely scratched the surface of what fasting can do, and I’ll probably dive into it further down the road. Comment below with your thoughts!
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