Metabolic Switching; Our Brain and Muscle on Steroids
By Tina Orr.
Many of the benefits of fasting stem from the metabolic switch and using fatty acids as fuel. This fat-burning mode initiates multiple physiological changes that are still being discovered. In essence, we are shown how the body uses its own fat to nourish our tissues, organs, brains, and muscles!
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783752/
I will touch on the various aspects of “the switch”, however, to properly give this subject the respect it deserves, a whole article can be written on each detail. Links to additional studies are provided.
The Switch
In simplistic terms, the metabolic switch is when our bodies use their very own fat as fuel. Fat cells found in connective tissue (adipocytes) release fat into the blood and get metabolized to free fatty acids (FFA). These fatty acids go to the liver and generate ketones (acetate, acetylacetate and β-hydroxybutyrate BhB). The ketones generated go to other cells with the brain and muscle being a priority. It is reassuring to know these ketones help preserve the function of brain and muscle tissue!
This chart (figure 1) beautifully illustrates the many pathways activated when we are using our fat as fuel. It also shows the responses of cells to the ketone BhB.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783752/figure/F1/
Getting to the Metabolic Switch
The length of time required to start this amazing physiological process can be anywhere from 12 hours to 48 hours, depending on the individual. When we get far enough into a fast, we have depleted liver glycogen stores and (thankfully) have now switched to using our own fatty acids and fatty acid-derived ketones. I find this way exciting, because, in my own experience, I have less hunger, more energy, and the knowledge that something truly amazing is happening. The ketones being utilized are great for the brain. In fact, there have been many studies on the Neuroprotective properties of ketones in patients with Alzheimer’s. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7699472/
Physiological Benefits
This chart summarizes in beautiful colour, the physiological responses of major organ systems, including the musculoskeletal system:
The various physiological systems — including blood circulation, brain function, intestinal health, liver function, cardiac activity, and adipose tissue — are intricately intertwined to enhance our resilience, intelligence, health, and physical strength.
“Examples of functional effects and major cellular and molecular responses of various organ systems to Intermittent Fasting (IF). In humans and rodents, IF results in decreased levels of circulating insulin and leptin, elevated ketone levels, and reduced levels of pro-inflammatory cytokines and markers of oxidative stress. Liver cells respond to fasting by generating ketones and increasing insulin sensitivity and decreasing lipid accumulation. Markers of inflammation in the intestines are reduced by IF. The insulin sensitivity of muscle cells is enhanced, and inflammation reduced in muscle cells in response to the metabolic switch triggered by fasting and exercise. Emerging findings further suggest that exercise training in the fasted state may enhance muscle growth and endurance. Robust beneficial effects of IF on the cardiovascular system have been documented including reduced blood pressure, reduced resting heart rate, increased heart rate variability (improved cardiovascular stress adaptation), and resistance of cardiac muscle to damage in animal models of myocardial infarction. Studies of laboratory animals and human subjects have shown that IF can improve cognition (learning and memory); the underlying mechanisms may involve neurotrophic factors, stimulation of mitochondrial biogenesis and autophagy, and the formation of new synapses. IF also increases the resistance of neurons to stress and suppresses neuroinflammation. *Demonstrated in animal models, but not yet evaluated in humans.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783752/
The Brain
As noted earlier, the ketones derived from free fatty acids are an excellent fuel for the brain. One of these fatty acid-derived ketones is β-hydroxybutyrate (BhB). BhB is an important energy source for the brain and provides additional benefits;
“BHB can also upregulate the expression of brain-derived neurotrophic factor (BDNF) and may thereby promote mitochondrial biogenesis, synaptic plasticity and cellular stress resistance” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913738
These same fatty acid derived ketones have been used in the treatment of epilepsy and, In 1911 French Physicians Guelpa and Marie recorded one of the first medical reports on fasting for treating this neurodevelopmental disease.
A great insight into the potential of therapeutic fasting in the treatment of mental/brain disorders can be found in “The Oldest Cure in the World”. In the chapter “What the Soviets Knew” Dr Yuri Nikolaev’s successful treatment of schizophrenia, characterized in part by abnormal brain structure and function, is discussed.
Preserving Muscle
One thing that stood out to me is the comparison between Intermittent fasting (thus flipping the metabolic switch) and Calorie Restriction (CR): Calorie Restriction can result in one-fourth of the weight loss be of lean body tissue. (OMG who wants that!) In contrast, a study of 34 men showed, through intermittent fasting of 16 hours a day lost fat mass yet retained lean body mass. This is huge and points out there is so much more than the simplistic calories in/calories out mentality.
Although this excerpt uses different terms, it is written in the context of the metabolic switch: “Interestingly, the decline in muscle mass that occurs during normal aging in mice is prevented by 40% CR/TRF (Time Restricted Feeding), and this beneficial effect on muscle is associated with increased activity in the 2–3 hours before feeding and improved performance in agility tests. When mice are maintained on a high-fat diet, they become obese when fed ad libitum, but when maintained on ADF(alternate day fasting ), they do not become obese and retain muscle mass” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783752/
Necessity of Physical Activity
It is important to note that the increased activity 2–3 hours before eating is a major factor in the benefits observed in the study. This is often overlooked. When the Russians used multi-day Therapeutic Fasting as a modality to treat Psychiatric Diseases, they gently encouraged patients to do some type of movement 2–3 hours a day. Even the well-known Buchinger-Wilhelmi Clinic in Germany has different levels of long hikes planned for their fasting residents. Fasting without physical activity before a large, nutrient-rich meal is like having sex without foreplay. In other words, it is essential to stimulate the muscle in order to build it.
Muscle/Human Growth Hormone
One thing to keep in mind is that during fasting Human Growth Hormone (Hgh) is increased. In the following video, Dr Pradip Jamnadas, a prominent cardiologist, shares a study that found a 2000% increase in HgH in men and a 1300% in women. As Dr. Jamnadas’ says, “Without HgH, you could be working out all day, and all you get is achy muscles; you will not grow muscle.” https://youtu.be/RuOvn4UqznU?si=n_S3gphSX9Xl4d_f
Fasting Quote’s
“Fasting is the greatest remedy — the physician within.”
Philippus Paracelsus, one of the three fathers of Western medicine
“Instead of using medicine, better fast today.”
Plutarch, a Greek biographer and moralist
“The best of all medicines is resting and fasting.”
Benjamin Franklin
Summary
Delving into the metabolic switch reveals a fascinating interplay between our biology and historical practices. From ancient Greeks utilizing fasting for peak physical performance to modern scientific understanding, the metabolic switch offers profound implications for health and well-being.
As highlighted throughout this discussion, the body’s ability to utilize its fat stores as fuel not only supports vital organs and muscles but also promotes cognitive function and preserves lean body mass. Furthermore, the historical context, ranging from Socrates to pioneering Russian physicians, underscores the enduring relevance of fasting in human health. As we continue to explore and apply the metabolic switch in various contexts, it becomes increasingly evident that this physiological process holds immense promise for optimizing health and longevity.
