Fasting for 36 hours can trigger several biological processes that may potentially improve fatigue and muscle-related issues and maintain the fat loss after losing it. These three things are the main issues associated with rapid weight loss programs like restrictive eating and intense exercise.
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Autophagy: Extended fasting initiates autophagy, a cellular “cleaning” process that removes damaged proteins and organelles. This can improve overall cellular function and potentially reduce fatigue.
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Mitochondrial biogenesis: Fasting may stimulate the creation of new mitochondria, the energy-producing structures in cells. This can enhance energy production and potentially alleviate fatigue.
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Increased growth hormone: Fasting can lead to elevated growth hormone levels, which may aid in muscle repair and growth.
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Reduced inflammation: Prolonged fasting can decrease inflammation in the body, which may help with muscle recovery and reduce fatigue associated with chronic inflammation.
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Improved insulin sensitivity: Fasting can enhance insulin sensitivity, potentially improving nutrient uptake in muscles and overall energy metabolism.
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Increased BDNF: Brain-derived neurotrophic factor (BDNF) levels may increase during fasting, potentially improving cognitive function and reducing mental fatigue.
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Ketosis: During extended fasting (typically after 12-36 hours, depending on the individual), the body depletes its glycogen stores and begins to rely more heavily on fat for energy. This leads to the production of ketones, which become an alternative fuel source for the brain and many other tissues.
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Increased fat oxidation: As the body adapts to using fat for fuel, it becomes more efficient at mobilizing and burning stored fat.
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Hormonal changes:
- Decreased insulin levels: Insulin, which promotes fat storage, drops significantly during fasting.
- Increased norepinephrine: This hormone helps mobilize fat for energy use.
- Elevated growth hormone: Growth hormone helps preserve muscle mass and can promote fat burning.
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Metabolic adaptation: Extended fasting can increase metabolic flexibility, allowing the body to switch more easily between burning carbohydrates and fats for energy.
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Improved insulin sensitivity: This can help the body manage blood sugar more effectively when food is reintroduced, potentially reducing fat storage.
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Epigenetic changes: Fasting may induce changes in gene expression that favor fat metabolism and energy efficiency.