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Introduction, Blood Glucose & Mortality, Mice Vs. Humans

Fasting is a popular topic and one that has an effect on many aspects of our health and wellbeing. Intermittent fasting, also known as time-restricted feeding, is the practice of eating at certain times in a 24-hour cycle or not eating for entire days. All people employ some form of intermittent fasting, as we don't eat during our sleep. Today, we will be discussing how intermittent fasting can impact weight loss, fat loss, muscle loss and gain, organ health, inflammation, sickness, recovery, exercise, cognition, mood, and lifespan. Also, we will discuss tools that can help make it as if you did not eat at all. Studies show that in humans, higher resting blood glucose is associated with mortality, however, in mice the opposite is true. Therefore, it is important to distinguish when a study was done in humans or in mice.

Neuroplasticity Protocols & Online Lecture

RETHINK EDUCATION: The Biology of Learning Featuring Dr. Andrew Huberman

This resource is an event recorded by Logitech which focused on how to be a more effective learner and teacher by utilizing modern principles of neuroplasticity. It includes a seminar which explains how different structures and tools can lead to faster and more effective learning of various skills. Additionally, an example of how the tools are applied in the music classroom of a teacher in Pasadena is included. The tools are listed in a plasticity super protocol, and can be applied to any learning or teaching format. The event is available now for free online.

Feeding, Fasting, Performance

Fasting and time restricted feeding are two sides of the same coin, and this podcast will focus on the latter. The goal is to help people understand the biological mechanisms and gain control over their mental and physical health. Knowing mechanisms gives you the flexibility to navigate through life and different scenarios. The podcast will explain the mechanisms as well as different tools to implement them. Nutrition is a controversial topic, but this podcast aims to help people gain control of their health and performance.

Calories-In, Calories-Out (CICO); Perfect Diets

Precise understanding of nutrition is essential to determine the best diet for individuals. Chris Gardner's 2018 study on weight loss showed that a healthy, low-fat diet and a healthy, low-carbohydrate diet with more dietary fats had no significant difference in weight change. Hormones, such as thyroids, insulin, and sex hormones, can have a profound effect on calories burned. Time restricted feeding has been shown to have positive effects on health parameters including weight loss, fat loss, muscle, organ, genome, epigenome, inflammation, exercise, cognition, mood, and lifespan. Therefore, there is no one perfect diet, but rather a perfect diet for individuals that should be based on what they did previously and what they plan to do in the future.

Feeding-Induced Health Conditions

Eating and fasting both have effects on the body, and the conditions they set are very important for overall health. When you eat, blood glucose and insulin levels go up, and this depends on what and how much you eat. When you don't eat, glucose and insulin levels go down, and other hormones like GLP1 go up. The Gardner study suggests that for weight loss, it doesn't matter what foods you consume, as long as you consume a sub-maintenance, caloric diet. However, adherence to a particular diet should also be taken into account, as individual goals such as mental performance and athletic performance may differ. Ultimately, what you eat and when you eat it both have an impact on your health.

Time Restricted Eating: When We Eat Is Vital

This landmark 2012 study by Satchin Panda of the Salk Institute of Biological Studies in San Diego demonstrated the effects of time restricted feeding without reducing caloric intake in mice on a high fat diet. The results showed that mice who ate the same amount of calories but only during a restricted feeding window maintained or lost weight, whereas those who had access to the food around the clock gained weight and became obese. Additionally, the mice who restricted their feeding window to a portion of the day showed improvement in certain health markers and even some reversal of previous negative effects. This research has been integral to further studies on intermittent fasting and time restricted feeding in humans.

The Eight Hour Feeding Window

A study was performed that required an eight hour feeding window for mice. This was due to the demanding nature of the study, as mice are known to hide food and the scientist had to be present for the duration of the feeding window. It is also revealed that the scientist conducting the study, was forbidden by their significant other from being in the lab for longer than 10-12 hours, in order to ensure the eight-hour feeding window. The article also discusses how this eight-hour feeding window impacts various parameters such as health and weight loss. In summary, the eight-hour feeding window was used in a study due to the presence and time constraints of the scientist conducting the study, and the impacts it has on various parameters.

Feeding Deep Into the Night Is Bad (In Humans)

Eating at the right times of the 24 hour cycle is important for health. The genes in the body and brain are on a 24 hour schedule and when these genes are expressed at the right times, health is enhanced. Restricting food to a particular phase of the 24 hour cycle can benefit things like lean body mass and fat loss. Light and when we view light is the primary way in which clock systems in the body get organized, and when we eat is as important as what we eat. The eight hour feeding window falls during the more active phase of the day, such as the early part of the day or the later part of the day, and not at night. Skipping meals occasionally can also be beneficial.

Liver Health

Time restricted feeding (eating within a certain window of time such as a 24 hour cycle) has been shown to improve liver health in mice and humans. This is because food intake sets certain conditions in the body that require energy and activate cellular functions, which can lead to an increase in pro-inflammatory markers if eating occurs too often. Eating on a regular schedule can reduce these markers and have positive impacts on weight maintenance, metabolism, and blood glucose regulation. This study has provided many potential benefits of time restricted feeding.

Time Restricted Feeding Protocol: Rules

Intermittent fasting is a type of eating protocol that involves restricting food intake for certain periods of time. It has been linked to health benefits such as improved metabolic health and weight maintenance or loss. The two key pillars of intermittent fasting are not eating or drinking any calories for the first hour after waking up, and for two to three hours prior to bedtime. It is important to note that certain liquids such as coffee and tea may break the fast. Overall, intermittent fasting is a great way to improve one's health.

When to Start & Stop Eating

Intermittent fasting is a way of eating that involves eating at least once every 24 hours. The two main questions related to this are when is the ideal time for the eating window, and how long should that eating window be? A new review in the journal Endocrinology Reviews provides a framework to answer these questions. It is best to extend the sleep-related fast into the morning or start it in the evening and not eat for at least the first 60 minutes after waking. It is also beneficial to extend the fasting to 9:00 AM, 10:00 AM, 11:00 AM or even 12 noon or later to take advantage of the deep fast that occurs during sleep. The length of the eating window can vary depending on individual needs and goals.

Gastric Clearance, Linking Fasting to Sleep

Intermittent fasting and time-restricted feeding are beneficial for health, but it can be difficult to limit eating to the middle of the day. It is best to start eating around 10AM or noon and finish eating at 6-8PM in order to benefit from the fasting related sleep. Eating too close to sleep will disrupt the fasting related sleep and it is important to prioritize both sleep and eating. It is also beneficial to have no eating for the first hour after waking, and no eating within two to three hours prior to bed. This allows for a transition from feeding to a fasted state and still allows for the special period of fasting during sleep.

Effects of Specific Categories of Food

Fasting can be managed through careful consideration of food volume, type, and its effects on glucose and insulin levels. Large meals with fats can take longer to digest than smaller meals, while liquids are digested faster. Establishing a feeding window that is comfortable to manage and fits into one's life is an important part of fasting. Factors such as glucose, insulin, and fat content should be taken into consideration when deciding what food to eat within the feeding window. Lastly, the timing of the feeding window should be chosen based on the individual's lifestyle.

Precision In Fasting: Protocol Build

My Circadian Clock is a free website where thousands of people have been studying the timing of meals by taking pictures of the food they are about to eat. This has created a "fetal gram" which shows the average time in which people eat. It has been found that people usually underestimate their eating window and it is usually 1-2 hours longer than expected. To achieve the benefits of time-restricted feeding, people should aim for an 8-hour feeding window or a 6-hour window, which will allow for a taper time before the fasted state is achieved. However, some people may require more food than this, making them an exception to the rule.

4-6 Hour Feeding Windows

Time restricted feeding of four to six hours has been studied and produces positive health effects such as increased insulin sensitivity and decreased blood pressure. However, it does not produce changes in body weight or fat loss. An 8-hour feeding window has been shown to be beneficial with respect to weight loss, fat loss, and adherence. One meal per day may result in under-eating, but is ideal for certain people's schedules. The length of the feeding window can impact hormones, which is important for sex, reproduction, work, and athleticism.

Protein Consumption & Timing for Muscle

Intermittent fasting and time restricted feeding have become popular methods of maintaining health and muscle mass. A study recently published in Cell Reports showed that ingesting protein early in the day helps to promote muscle maintenance and/or growth in both mice and humans. The study found that the expression of the clock gene BMAL is higher early in the day, which helps to regulate protein synthesis in muscle cells. It is important to note that eating protein early in the day does not mean that ingesting protein later in the day is bad for you. However, if the goal is to maintain or build muscle, then it is best to eat protein before 10am. As a result, if someone is aiming to gain the health benefits of intermittent fasting, they should not eat anything in the first hour after waking. Additionally, even if someone is not practicing intermittent fasting, they should still consider eating protein early in the day to support muscle maintenance and/or growth.

How to Shift Your Eating Window

Intermittent fasting and time restricted feeding have positive health benefits when done consistently. To optimize these benefits, it is important to keep the feeding window in a consistent part of the 24 hour cycle. People tend to underestimate the size of their feeding window, which can cause disruptions to the circadian clock mechanisms. To counter this, one should plan out a regular feeding schedule and try to stick to it. Any deviations from this should be done in moderation and short-term, as it can take two to three days to recover from the disruption. Finally, it is important to not be overly neurotic about this, but to find something that works for you and that you can keep consistent.

Glucose Clearing, Exercise & Compounds

Eating is not just about when you take the last bite or sip, but rather the fed and unfed states that your body is in. Taking a light walk or engaging in high-intensity interval training after eating can help clear out glucose from your system and transition from the fed to the fasted state. Glucose disposal agents such as Metformin and berberine can also be used to reduce blood glucose levels. However, caution must be taken to not clear out glucose that is already low, as this can cause extreme headaches. The dose and circadian component of these agents also vary from person to person. Understanding the fed and unfed states and how to transition between them can be beneficial for intermittent fasting and accessing the benefits of the fasted state.

Fasting and eating impact the levels of certain proteins in the body and can either promote cell growth or cell repair. Eating stimulates the protein MTOR, which is associated with cell growth, while fasting reduces MTOR and activates other proteins like AMPK and sirtuins which are associated with repair. Taking glucose clearing agents like berberine and Metformin can mimic fasting and can impact blood glucose levels. It is important to use caution when experimenting with these agents and to use a continuous glucose monitor to assess their effects.

Gut Health: Fasting, Clock Genes and Microbiota

Intermittent fasting can promote beneficial processes in the body such as AMPKs and sirtuins. It can also provide benefits to the gut microbiome, and has been shown to improve irritable bowel syndrome and colitis. It works by modulating clock genes which can reduce the amount of lactobacillus in the gut and increase the proliferation of other beneficial bacteria like acetobacter. It is thought that intermittent fasting has a direct effect on the mucosal lining of the gut, promoting a healthier gut microbiome. Therefore, many people who experience gut issues may benefit from restricting their feeding window to eight hours per day.

Non-Alcoholic Fatty Liver

Intermittent fasting has been linked to a reduction in non-alcoholic fatty liver disease. Non-alcoholic fatty liver disease was formerly only seen in alcoholics, but has recently become more prevalent in both adults and children. A recent study showed that the gut microbiome does not have an effect on this disease, but brown fat does. Brown fat stores can be increased with cold exposure and time-restricted feeding, and this may lead to a reduction in non-alcoholic fatty liver disease. Therefore, intermittent fasting can be beneficial for liver health.

Effects of Fasting on Hormones: Testosterone, Cortisol

Time restricted feeding has been shown to have beneficial effects on insulin profiles, body composition and performance. A study by Mauro et al., which looked at time restricted eating in elite cyclists, found that it had positive effects on performance. However, this study also found that time restricted feeding had a significant negative effect on free testosterone levels. It's important to consider where individuals are starting from in terms of their testosterone levels when looking at this study. Furthermore, cortisol levels were lower when time restricted feeding was used, which can offset the decrease in testosterone seen. Finally, it seems that an 8 hour feeding window is compatible with quality hormone health, even in high-performing athletes, and is a useful guide for those looking to benefit from intermittent fasting.


The relationship between food, body fat and hormones is a well-established one. Leptin, which is a hormone from body fat, signals to the brain to turn on puberty and for adults to maintain ovulation. Similarly, fasting or extreme exercise reduces testosterone levels and reduces fertility. Intermittent fasting may not be compatible with hormone health for everyone, so it is important to find an individual feeding window that works for them. It is recommended to transition into a time restricted feeding window gradually over 3-10 days to allow the body's hormone systems to adjust.

8-Hour Feeding Window: Weight Loss Without Calorie Counting

An eight hour time restricted feeding window has been studied in humans, particularly in obese adults. This study showed that with the eight hour window, a mild caloric restriction and weight loss can be achieved without calorie counting. Additionally, it was found to reduce blood pressure. This window has also been studied in non-obese adults and children, suggesting it is a good rule of thumb to use when incorporating time restricted feeding.

Eating Every-Other-Day

Alternate day fasting has been deemed safe and can lead to significant weight loss and reductions in blood glucose. Time restricted feeding, such as an eight hour feeding window, is the most tested and supported method of fasting and is the one most people should consider. Every other day fasting and five days of eating followed by two days of fasting have not been studied long-term yet to evaluate possible rebound effects. Exercise and work schedules can be difficult to incorporate with every other day fasting. Studies are ongoing to evaluate the effects of fasting on dementia, although no quality clinical peer reviewed studies have been published yet.


Studies which suggest that three or four diets are equivalent in terms of weight loss may not be accurate due to difficulty in adherence in the real world. Portion control is difficult for some, and neuroscience can be used to help decide the best eating plan for an individual. For example, some may find it easier to not eat some foods at certain points in the day, while others may prefer to eat the whole croissant instead of half. Ultimately, what works best for one individual may not work for another, and it is important to consider individual needs when deciding on a diet.

Mental Focus & Clarity

Time restricted feeding has become popular due to the mental clarity it provides and the removal of the need to make decisions when eating. It involves a designated eating window, and the food choices within that window can affect hunger and blood glucose. It also helps to remove the need to make decisions regarding portion control. Time restricted feeding involves the go-no-go circuitries of the basal ganglia, and is an appealing approach for those who don't want to have to think about their eating.

Enhancing Weight Loss from Body Fat: Hepatic Lipase

There is evidence that time-restricted feeding when in a state of caloric restriction can lead to more fat loss rather than loss of other tissues. This is accomplished by increasing hepatic lipase, an enzyme that metabolizes fat for lipolysis and energy production, as well as decreasing CIDEC, a molecule that can inhibit lipolysis. This data leads to the suggestion that time-restricted feeding with a sub caloric intake is the most scientifically supported way to ensure that weight loss is from body fat stores.

What Breaks a Fast? Rules & Context

Intermittent fasting or time restricted feeding is dependent on a variety of factors such as when you ate, how much you ate, and where you are in your circadian cycle. In general, drinks such as water, tea, and black coffee will not break a fast. Simple sugars may break a fast, depending on how long you have fasted and when your last meal was. Eating one peanut when deep in a fasted state will not break your fast, but eating a whole handful of peanuts might if you have recently eaten a meal that included carbohydrates. Everyone has to establish what's right for them, but it is important to be aware of when to initiate and end your feeding window.

Artificial Sweeteners, Plant-Based Sweeteners

It is still unclear whether artificial sweeteners such as aspartame and sucralose, as well as plant-based non sugar sweeteners like Stevia, break a fast. Studies on this topic are minimal, so it is best to determine this for yourself by wearing a continuous glucose monitor. Generally, artificial sweeteners are okay to consume in moderation, however, they may create a spike in appetite that makes it harder to adhere to the feeding window. Therefore, it is best to experiment with moderation to see what works best for you.

Glucose Clearing II, Cinnamon, Acidity, Salt

Salt can be used to help manage blood glucose levels and help people to feel better during fasting. The effects of acidity, such as from lemon and lime juice, can reduce blood glucose. A pinch of salt in water can help to stabilize bodily functions and reduce feelings of lightheadedness and shakiness. It can also reduce feelings of constant hunger and churning of the stomach. People with chronic hypertension should be wary of ingesting too much salt, but for most people it can be beneficial.

My Circadian Clock, Zero-App

Two free resources that can be used to explore and practice time-restricted feeding are My Circadian Clock, hosted by Satchin Panda and colleagues, and the Zero app. My Circadian Clock is a website which provides information, logs food intake and more. The Zero app is an app that marks when you begin and end your feeding window and initiates the beginning of the unfed state. Both are available for Apple and Android and provide excellent interfaces and progress logging capabilities.

Odd (But Common) Questions

The ideal feeding schedule is dependent on the individual's lifestyle and preferences. Brushing your teeth with toothpaste will not break your fast as long as you do not swallow it. However, a half glass of wine after dinner a couple of hours after eating will break your fast as it contains one gram of sugar. Continuous glucose monitors can be used to evaluate the effects of food and drinks on a person's fasting state. Additionally, it is important to monitor your caloric intake and the types of foods consumed during and in-between fasts.

Effects of Sauna & Dehydration on Blood Glucose

Saunas can increase blood glucose levels, as demonstrated by experiments with a continuous glucose monitor. When you dehydrate in a sauna and lose water, the concentration of sugar in your blood increases, resulting in a spike in glucose. This surprised many people when the data was shared on social media. Although this spike is not concerning to some, it is worth noting and discussing. For those concerned about blood glucose spikes, they might be worried. However, the physical and psychological benefits of sauna are valuable enough to some that they continue to use it, often around an hour or two before sleep.

The Ideal Fasting Protocol

Intermittent fasting (aka time-restricted feeding) is important for health benefits such as weight and fat loss. An ideal fasting protocol would involve avoiding food for at least an hour after waking up and two to three hours before bedtime. An eight hour eating window is ideal, but it can be adjusted according to individual needs. Eating late in the day is beneficial for hypertrophy and muscle building. The use of glucose disposal agents and behaviors such as walking and ingestion of lemon juice can help lower blood glucose. Lastly, recognizing one's own feelings of hunger and fullness is important to personalize one's own fasting protocol.