The Fasting Method – The Science2020-04-07T12:44:02-04:00

Fasting Science

Fasting is a time-tested solution for better health

Fasting Science

Fasting is a time-tested solution for better health

What is Fasting?

Intermittent fasting? Isn’t that starvation…?

No. Fasting is different from starvation in one vital way: control.

Starvation means you don’t know when you will eat next. It’s neither deliberate nor controlled.

Fasting, on the other hand, is entirely voluntarily done for spiritual, health, or any other reason.

Food is available – you’re just choosing not to eat it. That can be for any length of time, hours to days. Or – with medical supervision – even weeks. You can start or stop a fast for any reason, or no reason at all. Fasting has no standard duration.

Fasting may be the oldest and most powerful dietary intervention we know.

Consider the term ‘break fast.’ It’s literally the meal that breaks our daily fast. But to break a fast, we must be fasting. So, fasting is not some cruel and unusual punishment, but merely a part of everyday life. If you want to tip the balance towards weight loss, then you may increase the fasting portion of your day.

What are the benefits of fasting?

Weight loss is the most obvious health benefit. But, really, that’s just the start.

Other physical benefits of intermittent fasting include:

  • Weight and body fat loss5,6,8,9,11,12,37,38
  • Increased fat burning19
  • Lowered blood insulin and sugar levels20-22
  • Reduction in HbA1C23-25
  • Improved mental clarity and concentration13
  • Increased energy27-28
  • Increased growth hormone4,7,8
  • Activation of cellular cleansing by stimulating autophagy34-35
  • Reduction of inflammation36
  • Increased productivity (doesn’t take time and can be done anywhere)

Historically fasting periods were often called ‘cleanses,’ ‘detoxifications’ or ‘purifications.’ Whatever it was called, the idea was the same. Periodically abstaining from food helps clear toxins and rejuvenates the body.

How do I get Started?

Fasts vary

  1. What is allowed during the ‘fasting’ period – classic water only, with fasting fluids or even with fasting ‘training wheels’
  2. How long to fast – 16/8, 24 hours, 36 hours or extended fasting
  3. How often to fast

Once you decide on your fasting regimen, then it’s time to implement your plan. For that the
most important steps are:

  1. Education – Learn what to expect during fasting, what happens to your body, what potential side effects may occur
  2. Resources – troubleshooting, dealing with hunger, changing your environment to maximize success
  3. Community – Fasting is simple, but not easy. Having a supportive community around you can be the difference between tears of joy and tears of sorrow

The Fasting Method program can help you with all three steps to get started.

Fasting & Weight Loss

Fasting allows the body to use stored sources of energy – blood sugar and body fat.

What happens when we eat:

When we eat, we ingest more food energy (calories) than we can use at the time. The hormone insulin goes up, telling our body to store some of that energy, either as sugar in the liver (glycogen) or body fat.

EAT Food > Increase INSULIN > STORE Sugar, STORE Body Fat
  • Sugar: Individual glucose (sugar) units are linked into long chains to form glycogen and stored in the liver. This energy store is easy-to-access but limited in storage capacity.
  • Body Fat: Dietary glucose and protein in excess of glycogen storage capacity is turned into fat for storage by the liver in a process called de-novo lipogenesis (literally, “making new fat”). This form of energy storage is more complicated, but there’s virtually no limit to storage capacity.

These two food energy storage systems complement each other. Glycogen is easily accessible but has limited storage space. Body fat is more difficult to access but has unlimited storage space.

What happens when we don’t eat:

The energy storage process goes in reverse when we don’t eat (fasting). Insulin levels fall, telling the body to start burning the stored energy, glycogen and body fat.

No Food FASTING > Decrease INSULIN > BURN Sugar, BURN Body Fat

Glycogen is used first because it is the most easily accessible. It’s broken down into individual glucose molecules and moved into the bloodstream which distributes it to other organs and tissues for energy. Once glycogen stores are depleted, the body will start breaking down body fat for energy.

A very low carbohydrate diet reduces dietary glucose limiting glycogen production. This forces the body to burn body fat primarily when not eating.

The body only really exists in the fed (insulin high) state or the fasted (insulin low) state. It cannot exist in both states at the same time.

Either we’re storing food energy, or we’re burning stored energy. It’s one or the other. It’s a natural cycle. Feeding and fasting. Fasting and feeding. One follows the other as naturally as night follows day and day follows night.

If feeding and fasting are balanced, then there should be no net weight change. You don’t gain weight and you don’t lose weight. National surveys indicate that this was the dominant eating pattern in the 1970s before the obesity epidemic. Three square meals a day, no snacks. If you ate breakfast at 8 am and dinner at 6 pm, that is 10 hours of feeding and 14 hours of fasting every single day.

If feeding (insulin high) predominates, then we gain weight. If we start eating the minute we roll out of bed and don’t stop until we go to sleep, we spend all our time in the fed state. Over time, we’ll gain weight because our body spends insufficient time in the fasted state, where it burns that stored food energy. National surveys show that this is the current dominant eating pattern, in the midst of an epidemic of obesity unseen in history. The median time people spend eating is now close to 15 hours a day. Virtually the only time people fast is when they are asleep.

If we want to lose weight, then we simply need to increase the amount of time spent burning food energy. That’s intermittent fasting. It essentially allows the body to use its stored energy. After all, that’s what we stored it for. It’s a completely natural process.

Fasting & Type 2 Diabetes

Type 2 diabetes (DMII) is a fundamentally a disease of too much sugar in the body.

When we eat glucose, insulin allows it to be used by all the cells of our body for energy, and to store the excess away. Over time, if all our cells and storage system becomes overloaded, the remaining glucose spills over into the blood. Those high blood glucose levels are measured resulting in the diagnosis of type 2 diabetes.

Our body is like a sugar bowl. It starts off empty. Over time, if we are continually putting a little more sugar in than we take out, it becomes full, just like the cells of our body. Now, if we put in a little more sugar, it spills out into the blood. High blood sugars? Hello, type 2 diabetes.


If the core issue is glucose overfilling the cells, then the solution is obvious: get that glucose out of the cell!

There are really only two ways of getting the toxic glucose overload out:

  1. Stop putting glucose in. Low carbohydrate or ketogenic diets reduce the amount of dietary glucose. Fasting also eliminates carbohydrates – and all other foods, for that matter.
  2. Burn off the excess glucose. Your body requires a certain amount of energy every day to survive. The heart, brain, kidneys, liver etc. all require energy even if you are lying in bed. If you don’t eat food (fasting), then the body must burn its stored energy. The first place it will get that energy from is the glucose in the blood.

In type 2 diabetes, blood sugar levels are too high. If you don’t eat, your blood sugar levels will come down. So, why can’t fasting be used as a natural treatment for type 2 diabetes? There is actually no reason.

As you continue fasting, your body will start to burn body fat. As you lose body fat, the type 2 diabetes will start to reverse. Indeed, more and more research is showing that intermittent fasting has the potential to reverse type 2 diabetes without medications, surgery or even cost.



Fasting for Wellness and Autophagy

Fasting activates autophagy (a cellular cleansing process), lipolysis (fat burning), and may have anti-aging and neurological benefits.

In other words, fasting can benefit your brain and help your body stay younger!

Boost Brain Power

All mammals, including humans increase mental activity when hungry, and decrease when full. We’ve all experienced a food coma – think about how you feel after a big Thanksgiving meal. Are you mentally sharp, or dull as a concrete block? About the only mental challenge most of us can handle after that enormous meal is sitting on the couch watching football.

What about the opposite? Think about a time that you were really, really hungry. Where you tired and sluggish? No. You were probably hyper alert, your senses sharp as a needle.

Animals that are cognitively sharp and physically agile during times of food scarcity have a survival advantage, because it gives them an edge in finding food. If missing a single meal reduces our energy and mental clarity, we would have even more trouble finding food – making it more likely that we would go hungry again. That’s a vicious cycle ending in death. Who is more dangerous – the lion that just ate, or the hungry wolf?

Even our language reflects the relationship between hunger and mental clarity. When we say we are hungry for something – like hungry for power or hungry for attention – it doesn’t mean we’re slothful and dull. It means we’re on our toes, alert and ready for action. Fasting and hunger energises us, despite popular misconceptions to the contrary.

Scientific studies confirm this relationship. In one study of mental acuity and fasting, none of the factors measured – including sustained attention, attentional focus, simple reaction time or immediate memory – was found to be impaired26. The same study found no detrimental effect on cognitive performance or on sleep and mood.26

Slow Aging Process

Animal studies show that fasting has remarkable promise. Aging rats started on intermittent fasting regimens showed marked improvement in their motor coordination, cognition, learning and memory, believed to be due to a protein called brain-derived neurotrophic factor (BDNF). Both fasting and exercise significantly increase the beneficial BDNF effects in several parts of the brain. Compared to normal mice, mice on an intermittent fasting regimen showed less age-related deterioration of neurons and fewer symptoms of Alzheimer’s disease, Parkinson’s disease and Huntington’s disease.40

In human studies, a 30% reduction in calories significantly improved memory and synaptic electrical activity in the brain.

Lower insulin levels are correlated to better memory. Further, a higher body mass index is linked to decline of mental abilities and decreased blood flow to those areas of the brain involved in attention, focus, reasoning and more complex, abstract thought. So, fasting provides neurological benefits two ways: it decreases insulin and leads to consistent, maintained weight loss.

What is Autophagy?

The word autophagy, coined by Nobel Prize-winning scientist Christian de Duve, derives from the Greek words auto (self) and phagein (to eat). So, the word literally means “to eat oneself.”

Autophagy is a form of cellular cleansing: it’s a regulated, orderly process of breaking down and recycling subcellular components when there’s no longer enough energy to sustain them. Once all the diseased or broken-down cellular parts have been cleansed, the body can start the process of renewal. New tissues and cells are built to replace those that were destroyed. In this way, the body renews itself. But it only works if the old parts are discarded first.

Our bodies are in a constant state of renewal. While we often focus on new cell growth, we sometimes forget that the first step in renewal is destroying the old, broken-down cellular machinery. Autophagy keeps our bodies running well. The accumulation of older cellular components over time may be responsible for many of the effects of aging. So what stops autophagy? Our diet, especially protein intake.

When we eat foods, our bodies detect it through nutrient sensors like insulin. Dietary protein stimulates a nutrient sensor called the mammalian target of rapamycin (mTOR) pathway. Since food is easily available, there’s plenty of energy to go around, and no reason to cull some of the old, broken down sub-cellular parts. Autophagy is suppressed. In other words, constant snacking reduces autophagy, our cellular recycling process.

When we don’t eat (fast), the body senses the absence of nutrients and worries there won’t be enough food to feed the whole body. It must prioritize which cellular parts to keep. The oldest and most worn-out cellular parts get discarded. At the same time, fasting also stimulates growth hormone. When we eat again, this signals the production of some snazzy new cell parts, giving our bodies a complete renovation. Since it triggers both the breakdown of old cellular parts in the creation of new ones, Fasting may be considered one of the most potent anti-aging methods in existence.

Fasting, unique among diets, simulates autophagy. Simple caloric restriction isn’t enough, since even small amounts of any foods will turn off autophagy. Simply put, fasting cleanses the body of unhealthy or unnecessary cellular debris. This is the reason longer fast are often called cleanses or detoxifications.

Ongoing Research

In collaboration with the Intensive Dietary Management Clinic, The Fasting Method publishes research on fasting for menopausal women, colitis, type 2 diabetes, obesity, polycystic ovarian syndrome (PCOS) and nonalcoholic fatty liver disease (NAFLD).


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