The world of fasting has gained significant traction in recent years, with various methods promising a range of health benefits. Among these, the 86-hour water fast has emerged as a topic of interest, partly fueled by anecdotal accounts from high-profile figures like UFC president Dana White. White claims the fast made him feel “like a superhero,” sparking curiosity and debate about the safety and efficacy of this practice. This article delves into the details of the 86-hour fast, exploring its potential benefits, associated risks, and how it differs from other popular fasting methods like intermittent fasting.
What is a Water Fast?
A water fast involves consuming only water (and sometimes other low- or no-calorie liquids) for a specific period, abstaining from all food and caloric beverages. Water fasts can vary in duration, ranging from 24 hours to several days, and are sometimes practiced for religious reasons.
The 86-Hour Water Fast: A Closer Look
The 86-hour water fast, as the name suggests, involves restricting food intake to only water for 86 hours (approximately three and a half days). Dana White described his approach as a variation of a "seven-day water fast," opting for the shorter duration as a "safer" alternative. His protocol included:
- First 24 hours: Water with electrolytes (no calories).
- Next two days: Bone broth twice a day.
Is a Water Fast Safe?
While some consider water fasting relatively safe for healthy individuals, nutritionists generally advise against it without medical supervision. Deborah Cohen, D.C.N., an associate professor at Rutgers University School of Health Professions, states that it can be "downright dangerous" for individuals with diabetes, heart disease, or those prone to low blood sugar.
The following groups should not attempt a water fast without consulting a healthcare professional:
- Pregnant or breastfeeding women
- Individuals undergoing cancer treatment
- People with kidney, heart, or liver disease
- Those taking medications
Keri Gans, R.D., author of The Small Change Diet, emphasizes that even healthy individuals should consult their primary care physician before attempting a water fast, especially if they are on any medications.
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Potential Benefits of Fasting
While experts are hesitant to endorse the 86-hour water fast, research supports some benefits of fasting in general.
- Weight Loss: A 2023 review in Nutrition Reviews found that fasting for 5-20 days resulted in "mild to moderate weight loss" (2-10% of body weight). However, it's important to note that about two-thirds of this weight loss was from lean mass (muscle), raising concerns about muscle protein breakdown.
- Improved Metabolic Health: A 2022 study in Nutrients found that participants who underwent a 10-day fast under medical supervision experienced weight loss, lower blood pressure, and a "new metabolic homeostasis," indicating improved metabolic function.
- Ketone Production: Research has shown that fasting for 18 hours can lead to the metabolization of fatty acids into ketones, which can be used for energy.
86-Hour Water Fast Cons
Despite potential benefits, the 86-hour water fast carries several risks and potential drawbacks:
- Lack of Extensive Research: Scott Keatley, R.D., criticizes claims about water fasts as "pseudoscience," noting the lack of extensive, long-term human studies.
- Electrolyte Imbalance: Consuming excessive water without minerals can disrupt heart function.
- No Guarantee of Dramatic Health Improvements: There's "zero research" to support claims that water fasts dramatically lower the risk of cancer or Alzheimer's disease.
- Potential for Disordered Eating: Water fasting could lead to disordered eating patterns and may not result in lasting weight loss.
- Inability to Engage in Physical Activity: The lack of energy intake during a water fast can make it difficult to engage in physical activity.
- Loss of the Wrong Type of Weight: Much of the initial weight loss may be water, carbs, and even muscle mass.
- Dehydration: Restricting food intake, which contributes to daily water intake, can lead to dehydration.
- Orthostatic Hypotension: A drop in blood pressure upon standing can cause dizziness and fainting.
- Exacerbation of Medical Conditions: Water fasting may worsen conditions like gout and eating disorders.
How is it Different from Intermittent Fasting?
A key distinction between water fasting and intermittent fasting lies in the consumption of calories. Cohen emphasizes that a water fast involves "no calories for more than three days," while intermittent fasting involves "fasting for X number of hours and then consuming some calories." Gans adds that intermittent fasting includes actual food in the plan, not just water. Intermittent fasting is fasting for X number of hours and then consuming some calories.
Prolonged Fasting: A Comprehensive Overview
Prolonged fasting, characterized by consciously eating little to no food or caloric beverages for several days to several weeks, has garnered substantial interest as a potential non-pharmacological intervention.
Types of Prolonged Fasting
The main types of prolonged fasting are water-only fasting and Buchinger fasting. During water-only fasting, participants consume only mineral water or distilled water daily (∼2-3 L) without any food intake. Buchinger fasting, on the other hand, is a medically supervised program that is popular in central Europe. During this fasting protocol, small amounts of food are permitted daily.
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Effects on Metabolic Health Measures
Prolonged fasting appears to be a moderately safe diet therapy that can produce clinically significant weight loss (>5%) over a few days or weeks.
- Weight Loss: Prolonged fasting for 5-20 days produces potent increases in circulating ketones, and mild to moderate weight loss of 2-10%. Approximately two-thirds of the weight lost is lean mass, and one-third is fat mass. The excessive lean mass loss suggests that prolonged fasting may increase the breakdown of muscle proteins, which is a concern.
- Blood Pressure: Systolic and diastolic blood pressure consistently decreased with prolonged fasting.
- Plasma Lipids: The impact of these protocols on plasma lipids is less clear. While some trials demonstrate decreases in LDL cholesterol and triglycerides, others show no benefit.
- Glycemic Control: Reductions in fasting glucose, fasting insulin, insulin resistance, and glycated hemoglobin (HbA1c) were noted in adults with normoglycemia. In contrast, these glucoregulatory factors remained unchanged in patients with type 1 or type 2 diabetes.
Refeeding Effects
It was shown that 3-4 months after the fast was completed, all metabolic benefits were no longer observed, even when weight loss was maintained.
Adverse Events
Metabolic acidosis, headaches, insomnia, and hunger were observed in some studies.
Mechanism of Action
The mechanism responsible for these beneficial effects most likely involves flipping the metabolic switch. After 12 to 36 hours of fasting, the body switches from utilizing glucose (from glycogen stores) to fatty acids, and fatty-acid-derived ketones for energy. Adipocytes liberate free fatty acids, which are then transported to the liver and converted into ketones (ie, beta-hydroxybutyrate and acetoacetate). Ketone levels generally reach a plateau after 5 to 10 days of prolonged fasting and serve as the primary energy source for the body for up to 90 days. In addition to acting as a primary energy source, ketones also have direct physiological benefits.
Busting Myths About Long-Term Fasting
Many misconceptions surround long-term fasting, hindering its integration into mainstream clinical practice.
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Myth: Long-term fasting causes muscle and protein loss.
During fasting, the body initially uses circulating glucose from recent food intake. By 4-8 hours, glycogen becomes the primary glucose source after food is digested. As glycogen depletes, glucose starts to be produced by gluconeogenesis with contributions from lactate, glycerol, and amino acids. Fat oxidation becomes the main fuel to produce energy during fasting. The liver drives this shift. The mobilization of triglycerides generates glycerol and fatty acids, which can be oxidized to general energy to metabolized to produce ketone bodies.
After several weeks of fasting, when a steady state in the fasting metabolism is reached, total glucose production is approximately 80 g per day. This includes 10-11 g from glucose synthesis using ketone bodies, 35-40 g from recycled lactate and pyruvate, 20 g from fat-derived glycerol, and the remaining 15-20 g from protein-derived amino acids. However, whether this comes from the muscles and that this could cause a loss of muscle integrity is speculative because the body has internal protein reserves beyond muscle tissue. These protein stores can be utilized during prolonged fasting without compromising muscle integrity, such as through autophagy in the liver and in conjunctive tissues.
Measuring changes in body composition during fasting should be done using robust techniques, such as magnetic resonance imaging (MRI).
Any change in muscle composition should be put in parallel with a direct assessment of muscle function.
Altogether, during fasting, the body prioritizes fat and glycogen as sources of energy to preserve muscle tissue. While long-term fasting is associated with minimal mobilization of proteins for gluconeogenesis, there is no evidence that it leads to muscle loss or an alteration in muscle performance. On the contrary, studies suggest that fasting does not impair, and may even enhance muscle function. The fear of muscle loss during fasting is largely unfounded and based on speculation. Nonetheless, more studies need to be conducted to understand muscle preservation during fasting, especially when paired with physical activity.
Myth: Immediate weight gain after fasting
Our studies on long-term fasting using the Buchinger protocol indicate that while body weight often returns to baseline within a few months after fasting, the outcome varies significantly depending on the patient’s lifestyle. This primarily determines whether the weight loss is sustained.
It is clear that there is a risk of relapse after fasting or dieting if the lifestyle of individuals is not sustainably changed. This is why the fasting therapy according to the Buchinger protocol incorporates a multidisciplinary education program with nutrition, behavioral therapy and lifestyle modification, and psychological and emotional balance classes.
Myth: Fasting leads to intense, unbearable hunger
A common misconception about fasting is that it inevitably leads to intense, unbearable hunger. However, hunger is often inhibited during fasting, a phenomenon that likely evolved to help humans endure periods of food scarcity. One of the primary mechanisms that suppress hunger during fasting is the production of ketone bodies. As the body switches from using glucose to fat as its main energy source, these ketones not only fuel the brain and muscles but also reduce hunger by inhibiting the release of the hunger hormone ghrelin.
Myth: Energy levels are decreased during fasting
Many individuals fear that by abstaining from food, their bodies will become sluggish, making it difficult to maintain daily activities. In contrast to this popular myth, energy levels and well-being were increased in 109 participants of a 10-day fasting study. During fasting, the body’s sympathetic nervous system is activated, triggering a series of physiological reactions designed to maintain energy and alertness. This “fight or flight” system, increases the production of catecholamines such as adrenaline. Another factor explaining the sustenance of energy levels during fasting is the shift in the body’s energy sources. Ketones serve as an efficient fuel source for the brain, enhancing brain energy metabolism.