7-Day Fast: Benefits, Safety, and How To

Intermittent fasting is a popular mealtime pattern that cycles between periods of eating and fasting, and many individuals add the occasional prolonged fasts to their routine.  

Periodic fasts have been found to help improve insulin resistance, control blood sugar balance, boost cognition, and lower high blood pressure. But what happens on a prolonged 7-day fast?

Discover the health benefits of fasting for seven days, how to do it safely, and tips for a successful fasting experience. 

What is a 7-day fast?

A 7-day fast is a prolonged water fasting approach that involves total caloric restriction for a week. These fasts are typically performed only by consuming water, but low-calorie beverages, such as tea or coffee, are also permitted. 

Seven-day water fasts differ from dry fasts, which entail total calorie restriction and abstaining from water and other liquids. However, dry fasting can only be performed for 24 hours or less before becoming hazardous to health.

Week-long water fasts are generally safe for healthy adults and are associated with several health benefits. However, it’s important to consult a healthcare provider before attempting a 7-day fast to minimize the risk of potential adverse effects.

What happens during a water fast?

During the first 24 hours of water fasting, the body depletes blood sugar and glycogen, a storage form of glucose that’s deposited in the liver and muscle tissues. 

Once glycogen reserves are depleted, you’ll start to enter ketosis. This metabolic state pushes the body to burn fat to generate energy instead of using sugar as a fuel source. 

By 48 hours, you’ll likely reach full ketosis and transition into burning your own fat stores to fuel your cells. During this fasting stage, you may notice a reduced appetite and more mental clarity as the body starts to regenerate new brain cells. 

Autophagy, a process of removing and recycling damaged proteins and cellular organelles, also begins within the first two days of fasting, along with improved insulin sensitivity and reduced inflammation.

Around 72 hours and beyond, autophagy is significantly increased, aiding in the regeneration of the immune system and improving the responsiveness of insulin receptors, which are crucial for regulating glucose homeostasis and supporting metabolic health.

Watch the video below to learn more about the benefits of fasting for seven days.

Health benefits of fasting for 7 days 

Fasting is an age-old practice that’s still observed for spiritual, cultural, and health-related reasons worldwide. It impacts various bodily functions, including the immune system, hormonal balance, cognitive processing, and metabolic health.

Here are five incredible health benefits of fasting for several days. 

1. Weight loss

During a prolonged fast, the body depletes stored glycogen, which can lead to several pounds of water weight loss. 

Glycogen requires water to be stored, and for every gram of glycogen, three grams of water are retained, which explains why fasting can be an effective weight loss intervention.

In addition, caloric restriction forces the body to use body fat as a primary fuel source, which can promote significant fat mass loss. 

A study published in Nutrients found that participants lost nearly ten percent of their body weight, an average of 16 pounds, after a 10-day complete fast.

2. Promotes brain health

Damaged and misfolded proteins within the central nervous system are typically the result of environmental toxins, oxidative stress, and age-related cellular changes. The accumulation of these proteins can impact brain function and increase the risk of neurodegenerative diseases. 

Because caloric restriction stimulates autophagy, fasting can promote the removal of damaged and misfolded proteins and stimulate cellular renewal. 

Autophagy has been shown to reduce the risk of Alzheimer’s and Parkinson’s and enhance memory by destroying accumulated toxic protein aggregates in the brain.

3. Enhances stem cell production

Stem cells are unspecialized cells, meaning they have the unique ability to develop into various types of specialized cells. This versatility allows them to play a crucial role in tissue repair, regeneration, and overall cellular health.

These cells provide an anti-aging effect and can help extend longevity by replacing old cells with younger, better-functioning cells. 

“Stem cells replace damaged and aging cells that can’t repair themselves,” explains Dr. Berg. “Prolonged fasting for 72 hours or longer can greatly improve stem cell regeneration in the brain, pancreas, bones, colon, skin, and other parts of the body.”

4. Strengthens immune defenses

Autophagy dysfunction is associated with inflammatory diseases, including autoimmune conditions, as well as neurodegenerative disorders and various types of cancer.

Fasting-induced autophagy can help regulate innate immune functions and inflammatory responses by boosting white blood cell production. 

This process lowers the risk of chronic inflammation and strengthens the body’s ability to detect and target pathogens, microbes, viruses, and parasites. 

5. Potential anti-cancer effects

Mitochondrial gene mutations in cells can lead to abnormal cellular proliferation and carcinogenesis. 

Fasting may help lower cancer risk and suppress tumor formation due to autophagy’s role in removing and destroying damaged mitochondria.

Autophagy may also reduce the risk of tumor generation by regulating reactive oxygen species (ROS), which are unstable molecules that can directly damage DNA.

Research published in the International Journal of Molecular Sciences found that “Damage to mitochondria induces excessive ROS production, resulting in the promotion of carcinogenesis. Autophagy is a crucial mechanism that inhibits tumor generation, and impaired autophagy may result in oncogenesis.”

How to do a 7-day fast 

Going without food for seven days is challenging, particularly for individuals not accustomed to fasting or intermittent fasting.

For those new to water fasting, it's advisable to start gradually. This approach lets your body signal any issues, such as weakness or irritability, so you can eat before compromising your well-being. 

Gradually adopting a regular intermittent fasting routine and incorporating longer fasting practices, such as 24-hour or 48-hour fasts, can help you more comfortably prepare for and complete a 7-day fast.

While fasting, ensure you drink plenty of water and rest to prevent dehydration and overexertion, which may lead to side effects such as dizziness or fainting. 

However, excessive water intake can deplete electrolytes and lead to headaches, nausea, weakness, and extreme fatigue. This explains why it’s important to replenish electrolytes while fasting. 

You can also drink coffee and herbal tea while fasting if prepared without milk, creamer, sugar, or other calorie-dense ingredients. 

However, avoid protein drinks and bone broth. These beverages can raise blood sugar and insulin levels, which interferes with your fasting state and may knock you out of ketosis.

After completing your prolonged fast, reintroduce food gradually. To break your fast, start with small portions of easy-to-digest foods, like soups, stews, or smoothies. Over the next two to three days, gradually incorporate a variety of nutritious whole foods until you return to a regular eating pattern.

Safety and side effects 

Though fasting for prolonged periods can benefit those aiming to lose weight, improve insulin sensitivity, or rest the digestive system, there are side effects and contraindications to consider.

A poor diet before attempting a prolonged fast can exacerbate nutritional deficiencies, especially if essential nutrients, including electrolytes, B vitamins, and trace minerals, aren’t supplemented while fasting. 

Eating a large meal to break your fast can cause refeeding syndrome, a harmful shift in electrolytes and fluids that occurs when too much food is introduced too quickly.

Refeeding syndrome produces immediate symptoms that can range from mild, such as nausea, fatigue, and bloating, to severe, including difficulty breathing, high blood pressure, and seizures.

Those who are already underweight, diabetic, elderly, or suffering from inflammatory gut issues are at increased risk of refeeding syndrome and are more likely to experience severe symptoms.

Additionally, pregnant women, children, and individuals with histories of eating disorders, such as anorexia or bulimia, should avoid fasting and eat regular meals to ensure optimal nutrition.

Tips for a successful fast 

Fasting for seven days is challenging, and the initial hunger pangs can often lead many to quit within the first two days. 

However, there are effective strategies to manage and reduce symptoms, enabling you to successfully extend your fast.

1. Consume a nutritious high-fat diet 

Following a nutrient-dense diet before fasting can help minimize the risk of nutritional deficiencies during or after your seven-day fast. 

Focus on organic produce, wild-caught and grass-fed meats, and healthy fats like salmon, beef, avocados, and olives to ensure you receive a broad spectrum of essential vitamins and minerals.

Additionally, consuming a nutritious high-fat diet such as Healthy Keto® promotes ketosis and fat-burning before attempting a prolonged fast. This helps reduce fasting-related side effects, such as carb cravings and fatigue.

2. Replenish essential nutrients 

Supplements, including a sugar-free electrolyte powder, B vitamins, trace minerals, and omega-3 fatty acids, help replenish nutrients lost during fasting and reduce the risk of developing or worsening nutrient deficiencies. 

In addition, taking fasting-approved supplements can support overall health, enhance energy levels, and ensure you maintain balanced nutrition throughout the fasting period.

3. Stay hydrated

Staying hydrated while fasting is vital to prevent dehydration and it’s recommended to consume between 8 to 10 cups (2 to 3 liters) of water per day.

Certain herbal teas, such as chamomile, peppermint, and green tea, may also help suppress appetite and boost antioxidants while fasting. 

Bulletproof coffee, which contains medium-chain triglycerides (MCT) oil and grass-fed butter, can also satiate hunger while keeping you in ketosis. 

Because MCT oil and butter are pure fats, they support sustained energy and appetite control without disrupting ketosis, which explains why bulletproof coffee doesn’t break your fast.

4. Prioritize rest

Rest is vital when abstaining from food intake for extended periods. 

Food provides the body with fuel to survive and function, and it's important to avoid strenuous exercise when not eating to conserve energy and support your body's adaptation to caloric restriction.

Key takeaways

A 7-day fast is a water fast that involves abstaining from food for a week. These prolonged fasts have many benefits, including strengthening immunity, promoting significant weight loss, and inducing autophagy.

Though fasting is typically safe for healthy adults, it’s vital to consult a healthcare professional before attempting an extended fast, especially if you have an underlying health condition. 

Additionally, pregnant women, children, and those with histories of eating disorders should avoid fasting.

FAQ

1. Is a 7-day water fast good for you?

Yes, a 7-day water fast can have profound health benefits as prolonged caloric restriction forces the body to burn fat for energy. This induces a metabolic state called ketosis, which promotes weight loss, may improve cognition, helps lower blood pressure, and enhances insulin sensitivity. 

Additionally, prolonged fasts trigger autophagy, a cellular repair mechanism that has powerful anti-aging effects, supports immune defenses, and may reduce the risk of various cancers. 

2. How much weight can you lose on a 7-day fast?

How much weight you’ll lose on a week-long fast depends on factors such as age, metabolic flexibility, and your dietary patterns before starting a fast. 

However, most people report a weight loss of 7 to 12 pounds after fasting for seven days. 

3. Will I lose muscle if I fast for 7 days?

No, you won’t lose muscle if you fast for seven days. Fasting stimulates human growth hormone, which protects against protein loss and preserves muscle mass. 

During fasting, the body enters ketosis, the metabolic state of fat-burning, which means your body will burn fat until you eat again. Muscle loss doesn’t occur until starvation, which begins when the majority of the body’s fat stores are depleted.

4. What are the stages of fasting for 7 days?

Within the first 24 hours of fasting, the body depletes its glucose and glycogen stores, prompting the liver to produce ketones from fat. By 48 hours, full ketosis is achieved, maximizing fat burning. Furthermore, autophagy begins, a cellular process that recycles and repairs damaged cells. 

Between 60 and 72 hours and beyond, the body’s growth hormone levels increase, further enhancing fat metabolism and muscle preservation.

5. What should I eat after a 7-day fast?

Breaking your fast with a large meal could lead to refeeding syndrome, and it’s vital to reintroduce food slowly after prolonged fasting to minimize the risk of adverse effects. 

It’s generally recommended to break a fast with nutritious and easy-to-digest foods such as bone broth, soups, stews, or steamed vegetables and slowly introduce a variety of foods. 

6. Can I have coffee on a 7-day fast?

Yes, coffee has minimal calories and won’t break a fast unless it contains high-calorie ingredients, such as creamer, sugar, or milk. 

Drinking black coffee with MCT oil or grass-fed butter may help you fast for longer. Pure fats such as MCT oil and butter are directly converted into ketones, which can satiate hunger without breaking the metabolic fasting state. 

Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9503095/ 

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6274804/