Fasting, an age-old practice rooted in various cultures and religions, has re-emerged as a prominent trend in the health and wellness sphere. Among the diverse methods of fasting, the 36-hour fast has garnered significant attention for its potential to enhance longevity, promote cellular health, and support overall well-being. Prolonged fasting, characterized by restricting caloric intake for 24 h or more, has garnered attention as a nutritional approach to improve lifespan and support healthy aging.
Understanding the 36-Hour Fast
A 36-hour fast involves abstaining from consuming any calories for one and a half days, allowing only non-caloric beverages like water, tea, and black coffee. More specifically, the 36-hour fast is a type of intermittent fasting where you abstain from food for an extended period of 36 hours, typically from dinner on day one until breakfast on day three. For example, if you finish eating dinner at 7 PM on Monday, you would not eat again until breakfast at 7 AM on Wednesday.
Metabolic and Physiological Effects of Prolonged Fasting
During fasting periods of 12 to 24 hours, there is a metabolic shift from using glucose to utilizing lipid-derived ketone bodies and free fatty acids (FFA) as an energy source in response to caloric deprivation to maintain vital brain and tissue function (10). Lipolysis is upregulated during fasting, where triacylglycerol (TAG) from adipose tissue is hydrolyzed to FFA, which are mobilized into circulation to provide energy (19). Excess fat deposits in adipose tissues, as in the case of obesity, can be detrimental as they may contribute to diseases such as non-alcoholic fatty liver disease (20). Thus, approaches that can deplete the amount of stored fat in overweight and obese individuals are important strategies for improving overall metabolic health. Changes in lipids are critical as lipids constitute a wide range of cellular components, including cell membrane and cell signaling molecules, and disruptions in lipid metabolism have been implicated in several diseases, including metabolic syndrome (21) and Alzheimer's disease (22).
Key Benefits of a 36-Hour Fast
Autophagy Activation
Autophagy is a cellular process where your body cleans out damaged cells and regenerates new ones. This process is critical for maintaining healthy tissues, including hair follicles and skin cells. Studies have shown that fasting can trigger autophagy, especially during prolonged fasts like the 36-hour fast.
Enhanced Insulin Sensitivity and Fat Loss
A 36-hour fast can significantly improve insulin sensitivity, which is a crucial factor in metabolic health. With better insulin regulation, your body becomes more efficient at utilizing stored fat for energy.
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Reduction in Inflammation
Chronic inflammation can negatively impact various aspects of health, including the scalp environment and oral health. Studies suggest that fasting reduces pro-inflammatory markers, creating a healthier environment for hair growth and maintaining gum health.
Longevity and Cellular Health
Research indicates that fasting, particularly prolonged fasting like the 36-hour fast, can activate pathways associated with longevity. These include the reduction of oxidative stress and the promotion of DNA repair mechanisms.
Impact on the Plasma Lipidome
Prolonged fasting vastly remodels the plasma lipidome and markedly alters the concentrations of several lipid species, which may be sensitive biomarkers of prolonged fasting. Several lipid classes, including lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylethanolamine, and triacylglycerol were significantly reduced in the 36-h fasted state, while free fatty acids, ceramides, and sphingomyelin were significantly increased compared to overnight fast and fed states (P < 0.05). After correction for multiple testing, 245 out of 832 lipid species were significantly altered in the fasted state compared to baseline (P < 0.05).
Scientific Evidence Supporting the Benefits
The connection between fasting and its myriad of health benefits is supported by an expanding body of research. Trends in Endocrinology and Metabolism delves into how intermittent fasting impacts both immunity and metabolism. This study explains that fasting not only lowers metabolic inflammation and improves glucose metabolism but also triggers specific immune responses that communicate across various tissues such as the liver, adipose tissue, and skeletal muscle.
Considerations and Potential Drawbacks
On the other hand, PF can also have deleterious effects on health. For example, the effects of PF on the gut microbiome have been shown across species (15). Studies involving caloric restriction (800 kcal per day) over 8 weeks have exhibited reduced microbial abundance and diversity, a decrease in the production of short-chain fatty acids by gut microbes, and increased susceptibility to pathogens (16). In addition, PF has been shown to reduce lean muscle mass (17).
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Potential for Metabolic Defense Mechanism
Intermittent fasting (IF) approach to weight loss obviates the inconvenience of calorie counting required in daily caloric restriction (DCR). A metabolic defense mechanism (MDM) obstructs weight loss and facilitates weight regain possibly by increasing hunger and efficiency of exercise energy expenditure (EEf), and by reducing resting metabolic rate (RMR) and energy expenditure (EE) including physical activity (PA).
Individual Variability and Monitoring
The absence of increased hunger and changes in EE, the variability of the rate of weight loss in the 5:2-NC protocol, plus increased EEf in one M4:3-NC study, suggest that IF does not mitigate MDM, but that shortened UF period in M4:3-NC reduces the rise in BHB. Thus, the addition of a large meal on fasting days is unnecessary for the prevention of hunger and is counterproductive for increases in BHB and its potential health benefits.
Practical Tips for a 36-Hour Fast
Ease into It
Try not to go from eating to not eating all at once. Instead, try to cut back on food and drink intake over a few days or weeks.
Avoid Sugar
Food and cookies made from sugar can make you feel satisfied at first, but when your blood sugar goes down, you might become hungry and weak. To prepare for an experience like fasting, fill up on things like pasta, rice, meat, beans, and potatoes instead.
Cut Back on Activity
When you're fasting, try to take it easy on yourself. Try not to do much strenuous movement or exercise. Your body doesn't have the ability to replenish itself when you're not eating.
Read also: The 4-Hour Body Diet
Consider Medication
Before you start a fast, check with your doctor about any medications you might take. If there are medications you have to take every day, talk with your doctor about whether it's OK to take them without food.
Stop Slowly
When you're getting ready to finish your fast, get back to eating slowly. Don't eat a huge meal right away. Instead, spread out your meals and let your body adjust and get used to the process of digesting food again.
Cautions and Contraindications
Keep in mind that fasting too much or too often can be dangerous and cause dehydration, mental stress, and disrupted sleep.Also, doctors warn against fasting if you:
- Have diabetes
- Have kidney disease
- Are recovering from surgery or illness
- Are breastfeeding
- Are underweight
The 36-Hour Fast: A Lifestyle Choice
Choosing to fast requires mental strength and the ability to resist short-term gratification to pursue long-term goals. When you choose to participate in such a challenging exercise and succeed, you’ll likely experience enormous gratification and a renewed sense of accomplishment.