Fasting has been getting a lot of attention lately, and for good reason. Instead of manipulating what you eat, you manipulate when you eat. For many, this approach is much easier. I have been intermittent fasting for over four months now and I have many thoughts about this approach to eating.

First, let's distinguish between time-restricted feeding (TRF) and intermittent fasting (IF), as most people lump them both together. What is most commonly known as intermittent fasting, and what I have been doing, is actually time-restricted feeding. For example, the most popular protocol is 16:8 where you fast for 16 hours and eat for 8 hours per day. Intermittent fasting means that you fast intermittently (duh). What this means is that you may do periodic one, two, three, or even five-plus day fasts. Moreover, you could do alternate day fasting or 5:2 where you significantly restrict your calories twice a week.

While IF and TRF are technically different things the science behind them is the same and it's more about what works best for you. We will get into the science of both of these protocols and why I have been loving time-restricted feeding.

The Benefits of Intermittent Fasting and Time Restricted Feeding

Weight Loss/Body Composition

One of the main reasons that people do IF and TRF is for the weight loss benefits. While weight loss isn't quite as simple as calories in calories out, in general, to lose weight you do need to eat less. Rynders and colleagues found that IF and TRF yield equivalent weight loss to normal calorie restriction diets. However, they also found that those doing TRF or IF tended to adhere to their protocols for longer. Therefore, it seems like IF or TRF is the way to go over traditional calorie restriction. This is likely because eating fewer calories is easier when you get used to fasting. Your body no longer goes through constant cravings so you need less willpower to restrict your calorie consumption.

Metabolic Health

Metabolic health is one of the most prominent benefits of intermittent fasting. Half of all American adults and a quarter of children have pre-diabetes or type 2 diabetes. Moreover, diabetes is the number one risk factor for cancer, heart disease, and Alzheimer's. Together, these three diseases are the leading cause of death in the United States. Metabolic health is important.

One study found that intermittent fasting was more effective for patients with type 2 diabetes than calorie restriction. Moreover, Sutton and colleagues found that for those with pre-diabetes, meaning someone whose fasting glucose is higher than normal but not at the level of type 2 diabetes, time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress. Lastly, one meta-analysis found that for the general population, intermittent fasting can decrease BMI, fasting glucose, and leptin (a hunger causing hormone). At the same time, IF increases adiponectin which drives the breakdown of fat and increases insulin sensitivity while helping to quell inflammation.

Cognitive Improvement

Another great benefit of IF or TRF is the improvement in your cognition. One study found that calorie restriction correlates with an increase in working memory. While this was not directly on IF or TRF we have seen earlier that these protocols can often amplify the benefits of calorie restriction. Additionally, a study on ketogenic diets suggests that this way of eating may be essential for high-level cognition.

Again, a ketogenic diet is not the same as TRF or IF, however, the benefits of a ketogenic diet are from the fact that it puts you in a state of ketosis. Prolonged periods of fasting do the exact same thing. Ketosis is when your body starts to use ketones (derived from fat) for energy rather than glucose. This has numerous benefits, especially for your brain. The most prominent ketone is beta-hydroxybutyrate. This ketone is your brain's preferred source of energy because it can run much more efficiently thus improving cognitive performance.

Longevity

Longevity is about more than just life span, it's also about healthspan, or how long you live a healthy life. Intermittent fasting improves both. One study found that fasting up-regulates autophagy. Autophagy is a housekeeping mechanism whereby the body eliminates damaged organelles, misfolded proteins, and invading pathogens. It then recycles these products for general maintenance or it gets rid of them completely. When we eat all day our body has no reason to conserve energy. However, when we do fasting protocols like TRF or IF we force the body to get rid of material that it doesn't need thus lowering our risk of a wide range of diseases.

Another study by Cabo and colleagues found that "evidence is accumulating that eating in a 6-hour period and fasting for 18 hours can trigger a metabolic switch from glucose-based to ketone-based energy, with increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity."

Another key factor in fasting's ability to increase our longevity is that it strengthens mitochondria. According to research by Dr. Frank Shallenberger, virtually everyone over 40 has mitochondrial deficiencies if they aren't actively treating it. What's more, 48% of people under 40 also have a mitochondrial deficiency. The problem with eating throughout the day is that it makes our mitochondria work 24/7 without much strain. When we limit our food intake, the mitochondria experience hormetic stress (good stress) which forces the weak mitochondria to be broken down (autophagy) and replaced with stronger ones.

Lastly, when we eat all day long our pancreatic enzymes are all focused on digestion. However, these enzymes can also have healing effects on the body. Since the pancreas can only produce so many enzymes per day they never get to perform their healing functions because they are digesting foods. When we do IF or TRF we give these enzymes a chance to heal our bodies thus promoting health and longevity.

My Personal Experience with Time-Restricted Feeding

As I said earlier, I have been following a 16:8 time-restricted feeding protocol for about four months and have absolutely loved it. The reason I started intermittent fasting was to free up my morning so that I had more time to do my morning routine, workout, and get work done before the distractions of the day started to creep in. Four months later, this is still my favorite part about it. Mornings are absolutely critical for health and productivity. By removing the need to eat, I can maximize this time.

Moreover, the improved concentration that I feel while fasted amplifies the benefits of my morning. Before TRF, I would constantly cycle between hunger and fatigue from a meal. TRF removes this almost completely. During the first week, I did feel hungry, especially in the morning, but now I am almost never hungry. Even if I fast for 18 or 20 hours, my stomach never growls, and I am never uncomfortable. I still have a big appetite when I do eat but I never feel the need to eat which has changed the way I go about my entire day. By removing yourself from the constant cycle of being hungry, eating, getting a burst of energy, and then crashing, you can amplify your focus and productivity to new levels.

One thing that many guys my age worry about with fasting is losing muscle. I was worried about that too until I did some research. First of all, you can still eat the same amount of calories that you normally would, it is just in a smaller window. I have not struggled to get 3-4 thousand calories a day in a short time window. Secondly, with TRF I no longer eat close to bedtime. Growth hormone peaks while we are asleep. However, if we eat too close to sleeping growth hormone production significantly decreases making it harder to build muscle. Over these past four months, I have actually gained around ten pounds which is a much faster growth rate than I was experiencing before.

Overall, I have had nothing but positive experiences with 16:8 time-restricted feeding and I am actually starting to move towards an 18:6 schedule.

Should You Try Intermittent Fasting or Time Restricted Feeding?

While my experience has been great, TRF and IF are not for everyone. For example, if you have daily medication that you have to take with food, fasting probably won't work for you. That is not to say you can't get similar benefits through things like cold or heat exposure, exercise, and calorie restriction.

Moreover, some people find that prolonged intermittent fasting can start to have negative effects. For many people, cycling their fasting works very well. Maybe you do 18:6 TRF every other month, or you do a 24 hour fast twice a week, or a 5 day fast once per year. There are so many ways to do it and one is not objectively better than the other (although fasts over 72 hours will maximize autophagy). Find what works for you and stick with it.

One last thing to consider is that IF and TRF is not an excuse to eat whatever you want. The quality of your diet is still absolutely essential. It doesn't matter when or how much you eat if what you eat still harms you. Check out my articles on the basic principles of nutrition and staple foods for your diet to guide your eating choices. Along those same lines, if you want to lose weight, don't just eat the same amount of calories you normally would in a shorter window. You will likely still gain weight. In short, despite the great effects of IF and TRF, nutritional quality still reigns supreme.

Please DM or email me with any questions and let me know if you try any fasting protocols!