Hello everyone, Chris here. My wife, Jenny, and I have integrated intermittent fasting into our daily lives with amazing results, and we're thrilled to share our experiences and the fascinating science behind this healthful practice. I fast every day until noon, unless avocado on sourdough is on offer at an all-inclusive! Additionally, I undertake a full-day fast every Thursday, a three-day fast quarterly, and a five-day fast annually. And I can tell you, the benefits have been profound.

Intermittent fasting is not just about weight loss; it’s about enhancing the body’s function, longevity, and overall health. Contrary to the age-old belief that weight loss is merely about calories in vs. calories out, the reality is more complex. The timing of our meals can be as crucial, if not more so, than the amount we consume.

The Fridge and Freezer Analogy

To understand this better, imagine your body as a kitchen with a fridge and a freezer. The fridge represents your liver, which stores readily accessible energy in the form of glycogen. The freezer, on the other hand, symbolises white adipose tissue or 'white fat' – your body's long-term energy storage.

Our bodies typically prefer to burn the 'food' from the 'fridge' first. Only once these supplies are exhausted do we tap into our 'freezer'. By eating throughout the day, we continually restock our fridge, and the food in the freezer remains untouched.

Intermittent fasting, however, allows us to 'empty the fridge,' encouraging our body to tap into the energy reserves stored in the 'freezer,' promoting weight loss.

Beyond Weight Loss: Autophagy and Intermittent Fasting

Intermittent fasting goes beyond facilitating weight loss. It initiates a process known as autophagy, a cellular 'housekeeping' task where cells recycle waste products, repair themselves, and destroy harmful microbes. This process enhances cellular function, potentially reducing the risk of several diseases, including cancer and neurodegenerative disorders.

During a fast, as your body depletes the glycogen stores, it triggers autophagy, helping maintain the optimal health of your cells. Regular fasting could, therefore, lead to enhanced longevity and improved health outcomes.

Different Types of Fasting

While the concept of fasting may seem straightforward, there are actually a variety of methods to suit different lifestyles and health goals. Here are a few common types:

1. Intermittent Fasting (IF): Probably the most popular form of fasting, IF involves alternating periods of eating and fasting. The most common method, known as the 16/8 method, involves fasting for 16 hours a day and restricting your eating window to 8 hours, such as from noon to 8 p.m. Other variations include the 5:2 method (eating normally for five days a week and restricting calories to about 500-600 on two non-consecutive days) and Eat-Stop-Eat (involving a 24-hour fast once or twice a week).

2. Time-Restricted Eating (TRE): A subtype of IF, TRE focuses not on the number of calories consumed, but on the timing of meals. The popular 16:8 method is a form of TRE, but some people opt for even shorter eating windows, such as 4 or 6 hours.

3. Alternate Day Fasting (ADF): This involves alternating days of normal eating with days of either complete fasting or consuming 25% of your caloric needs.

4. Prolonged Fasting: This refers to fasting for extended periods, typically anything over 48 hours. It's crucial to approach this type of fasting carefully and preferably under medical supervision, due to the extended period without caloric intake.

5. Fasting Mimicking Diet (FMD): Developed by Dr. Valter Longo, the FMD involves consuming a very low-calorie diet for 5 consecutive days every month. This type of fast aims to provide the benefits of fasting while still allowing for some food intake.

Jen and I practice Intermittent Fasting and Chris does Prolonged Fasting.  We would only drink black coffee, water and non fruit based / milk free teas.  We prefer to have 0 calories during a fast, I tend to find that eating anything makes me more hungry rather than less.

Exercising During Fasting

A common misconception is that exercising while fasting may lead to fatigue or underperformance. However, many people, including myself, have found the opposite to be true. When your body shifts from burning glucose to burning fat for fuel - a state called ketosis - it can actually enhance your physical performance, particularly for endurance-based activities. The transition to using fat stores as primary energy sources can sustain longer workout periods without the need for regular carbohydrate intake.

Mental Clarity and Fasting

Additionally, fasting has a profound impact on cognitive function, leading to improved focus and mental clarity. During a fast, your brain undergoes several changes, including the increased production of brain-derived neurotrophic factor (BDNF), a protein that supports the health and growth of neurons. Fasting also stimulates the production of ketones, a type of energy molecule that the brain uses efficiently. Personally, I have experienced this as the lifting of a mental fog, resulting in sharper thinking and greater concentration. This mental clarity is one of the less-discussed but highly beneficial aspects of fasting, reinforcing its role not only in physical health but cognitive wellness too.

Harnessing the Power of Brown Fat

An interesting part of the fasting story involves 'brown fat,' a unique type of fat that burns energy instead of storing it. While white fat is like your energy 'freezer,' brown fat acts like a metabolic furnace, burning white fat to generate heat. This process, known as thermogenesis, is stimulated by cold temperatures.

Cold therapy, such as exposure to cold temperatures or cold water immersion, can increase brown fat stores in your body. When combined with intermittent fasting, this could enhance your metabolic flexibility, helping you burn fat more efficiently.

Timing Your Fasts for Optimal Performance

One might intuitively think that fasting should be reserved for quieter days with minimal activities, fearing a potential slump in energy. However, many fasting practitioners, myself included, have found that we're at our most productive during fasting periods. This is particularly true during later days of prolonged fasts, when the body is in full ketosis and efficiently utilizing stored fats for energy. So, don't shy away from scheduling fasts on busy days; you might be surprised by how much you can accomplish.

Hunger, Body Clock, and Ghrelin

Another intriguing aspect of fasting is the insight it provides into our body's hunger signals. Many of us associate hunger with an actual need for food. However, hunger often has less to do with energy needs and more with our body's internal clock and hormonal responses.

Ghrelin, known as the 'hunger hormone,' typically spikes before regular mealtimes, essentially telling our bodies that it's time to eat. This response is more a reflection of habitual eating patterns rather than immediate energy needs.

When fasting, after a brief adjustment period, ghrelin levels tend to decrease, reducing feelings of hunger. This highlights that our bodies have vast energy stores—over a million calories in the form of fat—that can be tapped into during periods of fasting. This reserve is not just for emergencies; it's perfectly designed for regular utilization. Fasting helps us align more closely with our body's natural energy needs, tapping into these reserves and encouraging a healthier, more efficient metabolism.

Measuring Blood Sugar and Ketone Levels during Fasting

An effective way to monitor the progression of your fast is by measuring your blood sugar and ketone levels. This can be done easily and affordably with a simple blood glucose monitor available from Amazon or other retailers. As you progress into your fast, you'll notice your blood sugar levels starting to decline while your ketone levels rise.

Initially, you might observe a ratio of blood sugar to ketones as high as 20:1. However, as the fast continues, this ratio will shift. When the ratio approaches 1:1, you're in a state of deep autophagy, where your body is efficiently recycling its damaged cells. From my personal experience, it usually takes me about 60 hours of fasting to achieve this ratio. As you become more accustomed to fasting, your body becomes "fat-adapted" - more efficient at utilizing fat for energy - and the time it takes to increase your ketone levels tends to decrease. I use a simple Google Sheet to track my fasting metrics, which helps me visualize my progress and understand my body's responses to fasting.

Safely Entering and Exiting a Fast

Now, while I tend to enter and exit fasts fairly abruptly without side effects, it's generally recommended to be gentler, particularly for beginners or those undertaking longer fasts. When entering a fast, start by reducing the size of your meals and increasing the time between them. This gradual approach can help minimize potential discomfort, such as hunger pangs or low energy levels.

Exiting a fast requires equal care. It can be tempting to immediately indulge in a large meal, but doing so can overwhelm your digestive system. Instead, break your fast with a small, nutrient-dense meal. Opt for foods that are easy to digest, such as broth, yogurt, or a small portion of cooked vegetables. Gradually reintroduce larger meals over the following days.

Remember, everyone's body reacts differently to fasting. Listening to your body and responding to its signals is essential in ensuring a safe and beneficial fasting experience. Whether you're embarking on daily or longer fasts, a gradual approach to entering and exiting fasts can help your body adjust and maximize the benefits.

In conclusion, intermittent fasting is an ancient practice, now backed by modern science, that holds a potential key to improved health and longevity. By changing not just what we eat, but when we eat, we can tap into our bodies' inherent mechanisms for maintaining optimal health and weight.

Jenny and I welcome you to join us on this exciting journey. At R1SE Yoga in Sheffield, we not only practice yoga to maintain our physical health, but also integrate fasting and other healthful practices into our lifestyle. Remember, it's not just about 'moving more and eating less,' it's about making holistic, informed decisions about our health and wellbeing.