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Fasting Decoded: How Long Should You Fast for Longevity?

Fasting for Longevity: Does It Work and How Long Should Your Fast Last?

The constant promotion of trending diets can be annoying at the very least and often confusing.

The focus for these diets is normally weight loss, but did you know there is a diet that focuses not on weight loss but on promoting longevity in very specific ways?

Weight loss is a fine goal, but it is rather narrow. Intermittent fasting can bring improvements to many aspects of your health, not just the number on the scale. It can bring about more comprehensive results and be more enjoyable than other diet plans that specify what you are allowed to eat.

As we introduce you to the practice of intermittent fasting, we hope you will see that, for certain people, it can be more sustainable and bring more noticeable results than other diets in vogue today. We hope to dispel doubt by indicating scientific evidence that intermittent fasting is conducive to a longer life.

Table of Contents

What Is Intermittent Fasting?

Fasting is going without food or caloric beverages for a longer period of time than you normally do between meals.

People who participate in intermittent fasting have a schedule that alternates between fasting (for 12+ hours or even days) and non-fasting, often during a shorter window of time. That is, more time is spent fasting than eating.

If you fast intermittently, you might have one of the following schedules:

  • Only eat between 1-9 p.m.

  • Eat regularly for two days, then eat nothing for one day

  • Eat regularly for one day, then eat nothing for one day

Is Fasting Good for Your Health?

While fasting can be good for health, everyone is different and what works well for one person might not work for another. Talk with your doctor before beginning to fast intermittently. The following conditions, for instance, preclude the safety of intermittent fasting:

  • Pregnancy

  • Breastfeeding

  • Being underweight

  • Malnourishment

  • Using some medications, especially those that lower electrolytes

  • Chronic disease

  • Poor health

A candidate for intermittent fasting should be in good health. If not, food deprivation could cause more harm than good.

Knowing How Long To Fast for Longevity and General Well-Being

It is important to be knowledgeable about the rationale behind different kinds of fasting and to have concrete, reliable evidence that fasting is beneficial before you undertake what might be a risky endeavor. Consult a healthcare professional, especially if considering extreme diets, such as a 5-day water fast.

Intermittent Fasting vs. Prolonged Fasting

Intermittent fasting generally involves a daily routine of fasting and non-fasting, whereas prolonged fasting is characterized by longer periods of fasting that occur less frequently.

Intermittent Fasting for 12 to 48 Hours

During intermittent fasting, people restrict themselves to water only or just to much fewer calories (for example, 25% of daily needs). Mayo Clinic provides a few approaches to accomplishing this:

  • Alternate-day fasting (ADF) – This entails fasting every other day and eating normally on non-fasting days. The modified version of this allows you to eat 500 calories on fasting days.

  • Time-restricted feeding (TRF) – This involves eating only during specific hours (usually a 6-12 hour window) and fasting at all other times.

  • 5:2 – You may eat normally for five days (not necessarily consecutive) and only consume 500-700 calories on fasting days.

Two glass jars of flavored water.

What Happens to Your Body During Intermittent Fasting?

Intermittent fasting initiates processes that may contribute in different ways to longevity:

  1. Weight loss occurs because the body’s fat stores are burned as energy.

During fasting, the body compensates for its lack of glucose by producing it from other molecules. Fat is one source of these other molecules and when it breaks down, the body’s level of ketones increases, bringing about cardiovascular and digestive health benefits.

After the body has been fasting for 12-24 hours, blood glucose lowers to the point where glycogen (the stored form of glucose that resides in the liver) must be broken down for energy.

When glycogen is depleted, there is a metabolic switch as glucose is formed through alternative pathways using certain amino acids, fatty acids, lactate, and glycerol as intermediates in the process of glucose production.

In another alternative pathway, the body breaks down triglycerides into fatty acids, which are used for gluconeogenesis. Ketones are a byproduct of the breaking down of fats for energy. Fat stores decrease, often resulting in weight loss.

Ketones may come from:

  • Your body’s fat stores

  • Your diet

  • Those produced by your liver in response to low insulin, which occurs as blood glucose decreases

Ketones may increase longevity by promoting heart health, a healthy weight, and low blood sugar levels.

  1. The body experiences less oxidative stress. A 2020 study detected a significant decrease in oxidation protein products in people who underwent TRF for 6 weeks.

  2. The body experiences less inflammation. A 2019 study discovered that fasting reduces the release of pro-inflammatory cells called monocytes. These cells are essential for immunity, but they can have damaging effects on body tissues if their levels are elevated by unhealthy eating habits.

  3. The body benefits from the expression of genes that activate autophagy. Autophagy is the body’s way of cleaning itself on the cellular level by destroying pathogens and degrading or recycling aged and dysfunctional cell components. This process may help ensure that unhealthy cells do not continue dividing and make you sick.

  4. Fasting promotes stem cell protection, self-renewal, and regeneration. It does this by:

    1. Reducing levels of protein kinase A, which causes stem cells to enter regenerative mode

    2. Breaking down some white blood cells, which causes a chain of events that causes stem cell-based regeneration of immune cells

Prolonged Fasting for 2 to 7 Days

Prolonged fasting involves a water-only diet or a fast-mimicking diet low in protein and sugar and high in unsaturated fat. A fast-mimicking diet brings about the same positive response as the water-only diet while still allowing your body to get important nutrients.

Prolonged fasting is not meant to be done routinely, as it can be dangerous. It should be done carefully and under the supervision of a healthcare professional.

What Happens to Your Body During Prolonged Fasting?

During prolonged fasting, people may experience benefits similar to those brought about by intermittent fasting, but to a more pronounced degree. These include a significant decrease in:

  • Blood pressure – Caloric restriction and a more relaxed nervous system (due to the absence of digestive processes) are two results of fasting that decrease blood pressure.

  • Blood glucose – Depletion of glucose is what brings about an increase in ketones.

Prolonged fasting has also been seen to lead to an improved fatty liver index, at least in the short term.

While ketone levels increase during intermittent fasting, the body doesn’t enter true ketosis, which depends purely on ketones for energy, until 72 hours of fasting. The possible benefits of ketosis include:

Prolonged fasting promotes cell, organ, and tissue regeneration by activating cell death and promoting autophagy, then activating stem cells that can replenish the old ones.

However, it is unclear whether prolonged fasting’s benefits come mainly from its influence on cellular aging or from the weight loss that it brings about.

It is critical to have a healthy refeeding period after prolonged fasting. That is, it is crucial to replenish your nutrient deficit without eating too much and without eating the wrong foods.

A woman outside drinking a flavored beverage.

5 Factors To Consider Before You Begin Fasting for Longevity

#1: Your Health Status

Consult with a healthcare professional, especially if you have any underlying medical conditions (e.g., diabetes, heart disease, or gastrointestinal issues) or are taking medications. Fasting may not be safe or suitable for everyone.

#2: Safety Precautions

If you are fasting for an extended period, have a backup plan in case you need to end the fast prematurely due to health concerns. Know when to seek medical attention.

Studies on prolonged fasters must be done in a clinic because of the probability of adverse side effects, including:

  • Malnourishment

  • Hypoglycemia

  • Rapid weight loss

  • Severely low blood pressure

  • Nutrient deficiencies

#3: Duration of the Fast

Decide how long you plan to fast. Some fasts last for a few hours (intermittent fasting), while others can extend for days or even weeks. Longer fasts generally require more preparation and monitoring.

Three plates set up to show how a one day fasting plan.

#4: Your Hydration Levels

Staying hydrated is crucial during fasting. Be sure you drink enough water or other non-caloric fluids (such as tea or coffee without caffeine) to prevent dehydration. Electrolyte supplements may be necessary for extended fasts.

#5: Supplement Regimen

Depending on the length of your fast and your dietary habits, you might need to take vitamins or minerals to prevent deficiencies. Consult with a healthcare professional to determine your specific needs.

Is Fasting for Longevity Good for Everyone?

Fasting is not good for everyone. The following people should not consider fasting, as it could pose a serious risk to their health:

  • Underweight people or people with an eating disorder

  • People with chronic disease

  • People taking medication for hypertension

  • Heart patients

  • Women who are pregnant or breastfeeding

Fasting can be an enlightening practice because it can reveal both strengths and weaknesses. A period of fasting can prove to be an interesting time for reflection as you consider how dependent your body is on food and how feasting and fasting affect not just your physical but also your social life.

Promote Longevity With the Help of Good Bitters

Finding the right balance of food is healthy for your mind and your body. Fasting can help you develop a healthier regard for food. That is, it can help orient you toward eating what your body needs rather than just what it wants. A healthier body can live longer.

If choosing to experiment with fasting, Good Bitters is here to offer consultation on holistic exercises and meditation to support your regimen. Good Bitters provides these consultations to clients to help them achieve their physical, emotional, and spiritual goals. The content in this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Disclaimer: The information on this website is taken from traditional wisdom and modern research/databases and is for educational purposes only. It is not intended to act as medical advice or to replace medical treatment. This information is not intended to diagnose, treat, cure, or prevent any disease. The statements and information on this website have not been evaluated by the FDA. Please consult a knowledgeable healthcare provider for your individual needs.

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