What are the health benefits of intermittent fasting? How does fasting affect mental health?
Mindy Pelz suggests that fasting has many benefits. Just a few are the restoration of your overall health by improving your immune system, aiding in healthy weight maintenance, and enhancing your mental health.
Let’s dive into these benefits of fasting.
1) Fasting Improves the Immune System
As your body’s primary defense against illnesses, your immune system plays a crucial role in maintaining your overall health. Pelz says that one health benefit of intermittent fasting is that it strengthens your immune system by:
Triggering autophagy: Lowering glucose levels forces your body to turn to cellular debris as an alternative energy source. This process, known as autophagy, strengthens cellular health by detoxifying, repairing, and removing damaged components and harmful pathogens. It makes cells more resilient against age-related decline and inhibits viral replication, counteracting degeneration and inflammation that can lead to various health challenges.
(Shortform note: Research supports the beneficial effects of autophagy, attributing it to a decreased risk of some cancers and neurodegenerative diseases. However, while research indicates that fasting can trigger autophagy, the vast majority of these findings come from studies conducted only on animals. As such, there’s little in the way of detailed, conclusive evidence regarding the relationship between fasting and autophagy in humans.)
Improving gut health: Fasting, by allowing the digestive system to rest, reduces gut inflammation, fostering the ideal environment for beneficial bacteria to thrive and spread. This rest phase also stimulates the growth of gut-healing stem cells. According to Pelz, these processes promote a microbial balance that supports your immune system in multiple ways, including enhancing cellular health and glucose regulation.
(Shortform note: In Super Human, Dave Asprey clarifies how microbial balance supports your immune system. Gut bacteria help maintain the integrity of your gut lining—the barrier between your digestive tract and bloodstream. Your gut lining plays a massive part in the health of your immune system because it absorbs necessary nutrients from your bloodstream and prevents toxins in your digestive tract from leaking into your bloodstream. When your gut bacteria are out of balance, your gut lining breaks down, fails to absorb nutrients, and leaks toxins into your bloodstream. In addition to fasting, Asprey suggests you can improve gut health by eating more fiber and reducing your exposure to antibiotics and antibacterial products.)
2) Fasting Aids in Weight Maintenance
According to Pelz, fasting helps you lose weight or maintain a healthy weight by:
Balancing insulin levels: When you fast, you prompt your body to metabolize its stores of glucose and fat for energy. This stabilizes your blood sugar levels, lowers your insulin production, and helps regulate your weight by preventing excessive fat storage. (Shortform note: Fung (The Obesity Code) argues that engaging in regular 24- to 36-hour fasts is the most reliable way to lower insulin levels, slow down fat storage, and prevent weight gain. He explains that regular fasting lowers your insulin levels long enough to reverse insulin resistance. When insulin resistance reverses, your set weight (the weight your body naturally tries to maintain) drops and your body adjusts by burning off fat until you reach the new, lower set weight.)
Suppressing appetite: Pelz suggests that each time you fast, ketones (chemical byproducts of fat metabolism) inhibit your hunger hormones, making you less inclined to overeat. (Shortform note: According to research, fasting suppresses hunger in two ways. 1) It decreases ghrelin levels (ghrelin stimulates hunger). 2) It increases leptin sensitivity (leptin signals satiety, making you feel full and satisfied).)
Metabolizing stubborn fats: Pelz says that fasting promotes the conversion of stubborn subcutaneous fats into metabolically active fats, which are easier for your body to burn for energy. (Shortform note: Research adds insight into this conversion process. Fasting alters the levels of two proteins (miR-149-3p and PRDM16) that influence where your body stores specific fats. Specifically, your body switches from storing fat subcutaneously (under your skin) to storing it viscerally (around your organs). While it may sound alarming to have more fat stored around your organs, it’s beneficial because your body can metabolize visceral fats more easily than subcutaneous ones.)
Stimulating growth hormone production: Pelz explains that, by decreasing blood sugar levels, fasting triggers a significant increase in hormones that facilitate fat-burning, muscle growth, and a healthy body composition. (Shortform note: Research indicates that fasting does increase growth hormone secretion, which in turn helps you to burn more fat. Growth hormones regulate cell reproduction and regeneration, and they stimulate the production of somatomedin C—a hormone that supports bone development and tissue growth. As such, these hormones are key to building and preserving lean muscle mass. Increasing your lean muscle mass raises your metabolic rate, thereby enabling your body to burn fat more effectively.)
3) Fasting Enhances Mental Health and Cognitive Functioning
Pelz argues that fasting improves both your mood and your mental acuity by:
Repairing neurons: Elevated ketone levels during fasting support the regeneration of damaged neurons, enhancing memory, focus, and mental clarity. (Shortform note: Gin Stephens (Fast. Feast. Repeat.) explains that fasting supports neurons by boosting the levels of a compound called brain-derived neurotrophic factor (BDNF). This compound protects your neurons from wearing down, which helps you think better and lowers your risk of diseases like Alzheimer’s and Parkinson’s. BDNF also regulates your mood, helping enhance mental clarity: Lower levels of the compound are linked to depression, and some research suggests that one reason antidepressants work is that they increase BDNF levels.)
Providing consistent energy: Pelz explains that, unlike glucose, ketones offer a stable energy source, preventing fatigue and supporting overall cognitive function. (Shortform note: Research clarifies that ketones provide more consistent and sustained energy than glucose due to two factors: 1) Ketones metabolize slower in your body, creating a slow-release energy supply that outlasts the quick burn of glucose. This gradual process prevents sudden drops in energy, staving off bouts of fatigue and hunger. 2) Ketones are more energy-efficient than glucose because they require less oxygen to yield energy, which enhances endurance and focus during sustained physical activities.)
Resetting dopamine pathways: Continuous eating elevates your dopamine (a pleasure-related neurochemical) baseline. Over time, this leads to an increased need for food to achieve the same level of pleasure. Pelz suggests that fasting diminishes this dependency and enhances the sensitivity of dopamine receptors, reducing your reliance on food for a sense of well-being.
(Shortform note: Research indicates that fasting recalibrates dopamine feedback loops, effectively curbing the tendency to overeat or associate food with pleasure. It does this by stimulating the release of dopamine when you’re not eating—meaning you feel pleasure in the absence of food. And because you already have dopamine in your system, your urge to eat diminishes and you require less food to feel satisfaction.)
Calming anxiety: According to Pelz, increased ketone levels trigger the release of GABA, a calming neurotransmitter that promotes relaxation and emotional stability. (Shortform note: Research clarifies that ketones facilitate GABA production in two ways. First, the process of breaking down and using ketones leads to the production of glutamate, the raw material required to produce GABA. As such, increased GABA production is a natural byproduct of ketone metabolism. Second, specific ketones inhibit the breakdown of GABA within the brain, thereby extending its calming effect.)
