“A little starvation can really do more for the average sick man than can the best medicines and the best doctors. I do not mean a restricted diet; I mean total abstention from food for one or two days.”: Mark Twain
No doubt, today we are finding several health benefits associated with fasting. But actually, our ancestors knew it already. If you look at any religion, they recommend fasting as the best source for healing and purifying yourself.
How to do it properly is the main question in today’s world, where numerous of fasting techniques are available.
What is FASTING
Fasting is a term used to describe a variety of eating patterns in which no or few calories are consumed for time periods that can range from 12 hours to several days. A reduction in caloric intake without malnutrition, has consistently been found to produce reductions in body weight and extend healthy life span across a variety of species, including non-human primates.
METABOLIC SWITCH in fasting
In addition to the weight loss effects and metabolic improvements, several other beneficial effects of therapeutic fasting have been described including improvements in lipid profiles, osteoarthritis, healing of thrombophlebitis, healing of refractory dermal ulcers, and tolerance of elective surgery.
One key mechanism responsible for many of these beneficial effects appears to be “flipping” of the metabolic switch. But what is this metabolic switch and how is it flipped? Here, we define the metabolic switch as the body’s preferential shift from utilization of glucose from glycogenolysis to fatty acids and fatty acid-derived ketones. The reason we use the word ‘preferential’ is because there is now a growing body of research to indicate ketones are the preferred fuel for both the brain and body during periods of fasting and extended exercise. Of relevance to weight management, this switch represents a shift from lipid synthesis and fat storage to mobilization of fat in the form of free fatty acids (FFAs) and fatty-acid derived ketones.
Aging effect reduced with fasting
Several studies found that people who fast on regular basis, looks younger than people who never did. Infact, people who eat frequently, never comes in the state of fasting (ketosis, approximately after 12 hours of cessation of food) and they look more aged than their fasting counterparts. This is because of increased Growth Hormone production during fasting. Growth Hormone is one of the prime hormone responsible for repairing and healing your body. But, if you will keep eating, it will never come in your body and will never be able to heal it. Because, Growth Hormone only comes when you are sleeping or you can say when you are in fasting state. So, if you will keep eating continuously, you will start aging pretty quickly than you should.
Fasting can improve your Brain Functionality
The decline in cognitive function with age is forestalled in mice maintained on 40% calorie restricted or time restricted fasting. For example, an early study showed 40% CR/TRF prevented age-related decrements in motor performance (rotarod test) and maze learning (14 unit T-maze) in mice. Although the cellular and molecular mechanisms by which IF enhances cognitive and motor performance have not been established, the shift to ketone utilization appears to be one of the key biological mechanisms that prevents age-related reductions in brain white matter integrity, and preserves spatial memory.
Emerging findings also suggest other possible mechanisms through which fasting (IF) can maintain or even enhance cognitive function during aging. For example, both normal weight and obese mice maintained for three months on 40% CR/TRF exhibit an increased density of dendritic spines on hippocampal dentate granule neurons, and this increase in synapse numbers is correlated with an increased level of brain-derived neurotrophic factor (BDNF). It is well known that BDNF plays fundamental roles in learning and memory and also mediates the anxiolytic and antidepressant effects of exercise and antidepressant drugs. BDNF signaling may play important roles in the enhancement of synaptic plasticity by IF, as well as in the production of new neurons from stem cells (neurogenesis) in the hippocampus. Recent findings suggest β-OHB also has important signaling functions involving activation of transcription factors. In neurons, β-OHB induces the expression of BDNF, which, in turn stimulates mitochondrial biogenesis and the formation of new synapses. In these ways, events triggered by the metabolic switch may play major roles in the optimization of performance of the brain and body by fasting (Intermittent Fasting).
Numerous studies have shown alternate day fasting (ADF) can protect neurons in the brain against dysfunction and degeneration in animal models of a range of different neurological disorders including epilepsy, Alzheimer’s disease, and Parkinson’s disease and stroke. For example, mice maintained on ADF for three months prior to transient occlusion of the middle cerebral artery (an animal model of focal ischemic stroke) exhibit highly significant reductions in brain damage and neurological deficits, and a reduction in stroke-induced reactive neurogenesis. The underlying mechanisms likely involve both activation of adaptive stress response signaling pathways in neurons by neurotrophic factors and neurotransmitters, and circulating factors. It is well established that the ketone β-OHB can suppress epileptic seizures, and emerging findings suggest β-OHB may also play a role in the neuroprotective effects of IF in animal models of Alzheimer’s and Parkinson’s diseases and stroke.
Fasting can also increase Lean Muscle Mass
The ketones are transported in high amounts into cells with high metabolic activity (muscle cells and neurons) where they are metabolized to acetyl coenzyme A, which then enters the tricarboxylic acid (TCA) cycle to generate ATP. Through these physiological processes, ketones serve as an energy source to sustain the function of muscle and brain cells during fasting and extended periods of physical exertion/exercise. Thus, it appears when the metabolic switch is flipped, the primary energy source for the body shifts from glucose to FFA derived from adipose tissue lipolysis and ketones, which serve to preserve muscle. In support of this, retention of lean mass is increased following Intermittent Fasting regimens for weight loss as compared to continuous calorie restriction regimens in humans. Additionally, in mice, the decline in muscle mass that occurs during normal aging is prevented by time restricted feeding (TRF) involving 40% caloric restriction.
There are a few potential mechanisms through which a shift to fatty acid and ketone oxidation, relative to glucose oxidation, may serve to preserve muscle mass. Muscle cells store triglycerides in lipid droplets providing a local source of fatty acids that are utilized for β-oxidation and ketone generation during periods of prolonged fasting and extended exercise (see Nakamura et al., 2014 for review). The transcriptional regulator PPAR-α induces the expression of genes that mediate fatty acid oxidation in muscle cells, and also regulates muscle cell mitochondrial biogenesis and glucose metabolism. PPAR-α gene targets that mediate a shift in muscle cell fuel preference from glucose to fatty acids during fasting and endurance exercise include the fatty acid translocase CD36, fatty acid binding protein 3, mitochondrial uncoupling protein 3, PGC-1α, pyruvate kinase dehydrogenase 4 and forkhead box O1A. Mice with a muscle cell-specific knockout of the PPAR-α gene exhibit reduced numbers of oxidative fibers in their tibialis muscle, whereas overexpression of PPAR-α results in increased numbers of oxidative fibers. Mice lacking PGC-1α only in skeletal muscle are exercise intolerant and their muscle cells do not exhibit functional adaptations to exercise. The emerging evidence therefore suggests critical roles for metabolic switch-associated signaling pathways in both acute functional adaptations to bioenergetic challenges and the long-term increases in muscle growth and endurance capacity that accrue from intermittent metabolic switching.
Based on the findings described above, many experts have proposed IF regimens can improve body composition in overweight individuals; however, the effects of this dietary approach on body weight and body composition in humans are not currently well understood. In this paper, we briefly review the evolutionary underpinnings of optimal brain and body function in the fasted state and historical experience with fasting in humans. We then review the effects of different types of IF regimens on cellular, systemic, and performance-based outcomes from pre-clinical studies. In the final section, we review findings from human clinical trials that have tested the effects of IF regimens on changes in body composition, cardiometabolic health, and performance outcomes in humans.
An early study showed when rats are maintained on ADF beginning at 10 months of age, their average lifespan is increased by 30% compared to littermate rats fed ad libitum. The Alternate Day Fasting rats maintained a lower body weight and, when provided with running wheels, maintained a high level of daily running compared to control rats fed ad libitum.
Types of Fasting
Today, we know numerous ways of fasting. Traditional way, in which we fast for full day. Alternate Day Fasting (ADF), in which we fast on alternate days and consume normal diet on next day. Alternate Day Modified Fasting (ADMF), is similar to ADF. Just in ADMF we consume fewer calories on alternate days. For example, normal calories on day 1, and less than 500 calories the next day. Next is 5:2 method of fasting, in which we fast for 2 days in a week and normal diet rest of the days of the week. Next is intermittent fasting, also known as time restricted fasting. In this method, we choose a timeframe to eat and to fast. Timeframes can be like 12:12 (12 hours of fasting followed by 12 hours of feeding), 16:8 (16 hours of fasting followed by 8 hours of feeding), 20:4 (20 hours of fasting followed by 4 hours of feeding).
You can choose any method, fasting has proven better way to loose fat and make a healthy lifestyle than only calorie restricted diets. Obviously, calorie restricted diet has benefits, but some adverse health effects as well like decreased muscle mass.
These are some latest findings related with fasting. But we all knew before that fasting is associated with better health. Recent findings support religious belief that fasting can make your body heal better. In addition to weight loss, fasting can improve your lean muscle mass, reduce aging effect, help your body repair itself better, help you to fight with many diseases, and also, it will make you feel better for sure.