Log In
Blog /
Fasting types
13 min read
Evidence Based

7-Day Fast: What It Is and How To Lose Weight With It

Intermittent fasting is a popular and effective method for burning fat and improving lifestyle habits. This time-restricted eating takes many forms, but some individuals choose to push their limits by experimenting with extended fasting periods of 2, 3, or even 7 days.

However, questions arise regarding the safety, efficacy, and whether this approach is considered a “smarter” diet. To understand the implications of a 7-day water fast, it’s important to examine scientific research and expert opinions.

Keep reading to explore the benefits, risks, and findings of the 7-day water fast.

Post Thumbnail

What Is a 7-Day Water Fast?

A 7-day water fast is a type of fasting in which individuals abstain from food for an entire week. The specifics of what one can consume during this period may vary, depending on personal preferences and physical capabilities.

For those who choose a more lenient approach, certain low-calorie or zero-calorie drinks, such as black coffee or herbal tea, may be allowed. In some instances, 7-day fasting could even involve reduced food intake.

However, a strict 7-day water fast permits only the consumption of water and supplements.

While week-long water fasts have historically been practiced for religious or spiritual reasons, they can also serve as a means for weight loss or detoxification.

Naturally, abstaining from food for an entire week can be challenging and may not be suitable for everyone, particularly for those who have never fasted before.

Generally, water fasting for 7 days is safe for healthy adults when done correctly. However, it is crucial not to extend the fast beyond this period, as studies indicate that fasting for 8 days or longer can result in adverse metabolic effects and dehydration.

For individuals who are new to fasting and looking to give it a try, it is advisable to start with more manageable intermittent fasting styles, such as the 12:12, 14:10, 16:8, and 20:4 methods, before attempting a 7-day fast.

Take a
1-minute quiz

and discover how much weight you can lose with DoFasting!

What happens during the 7-day fast

A 7-day water fast can improve health by prompting your body to undergo the following phases:

  • During the first 18 hours: Entering ketosis
  • Between 18–72 hours: Burning deep fat stores
  • After 72 hours: Peak of autography

Ketosis is a metabolic process when your body uses fat as its primary energy source instead of glucose. This shift happens when you follow a low-carb diet like keto, a calorie-restricted diet, or a fasting plan, which decreases glucose reserves derived from the carbohydrates you consume.

As your body enters ketosis, it mobilizes and oxidizes fatty acids, reducing insulin levels. This phase supports weight loss as your body transitions to a fat-burning process, utilizing fat for fuel.

While the overall effects of ketosis are positive for your long-term health, you might also notice certain side effects that will pass as your body adapts to the fasted state, including:

  • Fatigue
  • Headaches
  • Nausea
  • Increased hunger or thirst
  • Bad breath

Between 18-72 hours into your fast, your body begins burning deep fat stores by utilizing ketone bodies for energy. This occurs as your body depletes stored glycogen, a form of glucose found in the liver and muscles, and actively converts fat into energy.

As this process continues and fat stores are exhausted, autophagy commences. Autophagy is a cellular recycling process that repurposes old and damaged cell components to create new, healthy ones. This essential process plays a crucial role in maintaining cell health.

During this phase, you might experience some side effects like reduced appetite and fatigue.

After 72 hours of fasting, you’ll reach the peak of autophagy. Extended fasts and autophagy stimulate the secretion of human growth hormone, which is vital for muscle, bone, and organ growth, as well as for regulating metabolism and maintaining overall well-being.

Autophagy is essential for several reasons:

  • It recycles damaged cell components, transforming them into fully functional cell parts and creating healthier cells.
  • It eliminates nonfunctional cell components.
  • It removes viruses and bacteria.

Research suggests that autophagy can help reduce the risk of type 2 diabetes, Alzheimer’s and Parkinson’s diseases, and even cancer.

The various stages your body undergoes during a 7-day fast yield numerous health benefits.

Health Benefits of 7-Day Fasting

You already know what happens to your body while abstaining from food for prolonged periods. Let’s now dig into why these changes are positive for your health.

Weight and body fat loss

Weight loss is a primary motivation for many people who choose to try a water fast. Some find it more manageable than a low-calorie diet because it eliminates the need to count calories and constantly restrict oneself.

While both fasting and low-calorie diets can lead to weight loss, they differ in their approach and the body’s metabolic response.

Fasting helps with weight loss by boosting your metabolism through the stimulation of certain hormones and the utilization of stored fat for energy. This process, known as lipolysis, involves breaking down stored fat into molecules called fatty acids, which can be used to produce energy. When fasting, your body remains in a fat-burning mode and actively taps into fat stores for energy.

During a water fast, you naturally consume fewer calories than usual, which also contributes to weight loss. As your body remains in a fat-burning mode and utilizes fat stores for energy, you can expect to lose up to 1 pound per day.

Cellular health and autophagy that rebuilds your body

Autophagy is the body’s cellular repair system, responsible for transforming unusable, damaged cells into new, healthy ones. This process plays a crucial role in maintaining cell health and can help prevent the development of various chronic diseases.

Chronic diseases that may be mitigated by autophagy include diabetes, liver disease, autoimmune diseases, cardiovascular diseases, and Alzheimer’s disease. Moreover, the effects of autophagy are currently being explored in cancer chemotherapy treatment and may contribute to reducing cancer risk.

Both intermittent fasting and multi-day extended fasting can initiate autophagy. This occurs because hormone levels fluctuate during fasting, enabling cells to break down and eliminate damaged proteins and organelles.

Balanced insulin and blood sugar levels

Insulin is a hormone crucial for maintaining normal blood sugar levels. When blood sugar levels are too high, the pancreas releases insulin to lower them.

Elevated insulin levels can result in insulin resistance, while low insulin levels can cause hypoglycemia.

Maintaining balanced insulin and blood sugar levels is essential for preventing chronic diseases such as type 2 diabetes, cardiovascular disease, and inflammatory disorders.

Keeping your insulin and blood sugar levels stable can also help regulate your weight. Blood sugar imbalances, on the other hand, may lead to cravings for high-sugar foods and overeating.

A 7-day water fast prompts your body to rely on stored fat for energy instead of a consistent supply of glucose from carbohydrates. Fasting lowers insulin levels, which can help improve insulin sensitivity.

Simultaneously, the body breaks down fat cells and releases fatty acids into the bloodstream. These fatty acids are essential for generating and sustaining energy levels while reducing the amount of glucose that insulin must remove from circulation.

It’s important to note that balanced insulin and blood sugar levels can aid in suppressing hunger.

Reduced appetite and cravings

During or after the 7-day water fast, you may notice a decrease in cravings and a suppressed appetite, which can be attributed to several factors.

Firstly, fasting improves insulin sensitivity, which in turn helps to suppress appetite. Greater insulin sensitivity allows the body to effectively respond to insulin and absorb glucose from the blood, contributing to stable blood sugar levels and reduced appetite.

Secondly, fasting lowers the levels of ghrelin, a hormone that stimulates hunger. As the stomach remains empty for an extended period, the body begins to interact with other appetite-regulating hormones, such as leptin.

In addition to these physiological changes, completing the 7-day fast can provide psychological benefits, and the sense of achievement upon finishing the fast can help to reduce further cravings and feelings of hunger.

Risks and Side Effects of 7-Day Fasting

Prolonged fasts, like the 7-day water fast, can lead to significant changes in your body’s essential functions. Naturally, water fasting may present some risks you should consider before deciding to take on this challenge.

Possible muscle loss

Muscle loss refers to the thinning of muscle mass, which can manifest as numbness, weakness, or tingling in your limbs.

During a 7-day water fasting period, your body enters ketosis and relies on fat stores for energy rather than carbohydrates. However, it may also break down muscle tissue for energy, leading to muscle loss. This risk increases as the duration of the fast extends.

To minimize this side effect, consume plenty of protein before starting the fast. After the fast, you can regain lost muscle mass through regular exercise and proper nutrition.


Even though it may seem counterintuitive, it is possible to become dehydrated during a water fast. Throughout the day, your body loses fluids through sweat, urine, and regular bodily functions like breathing.

Approximately 20-30% of your daily water intake comes from the food you eat. As a result, it’s essential to drink enough water during the 7-day water fast to compensate for the loss of fluid from food. To do so, aim to drink at least eight 8-ounce glasses of water per day.

Dehydration can cause symptoms such as nausea, constipation, dizziness, headaches, and low blood sugar, which may also be attributed to an imbalance of electrolytes. To avoid these issues, make sure to stay adequately hydrated throughout your fast.

Imbalance of electrolytes

Electrolytes are crucial in various bodily functions, including nerve and muscle function, hydration, and blood pH balance. They also help maintain the equilibrium between fluids inside and outside your cells. The primary components of electrolytes are sodium, magnesium, potassium, and calcium.

During a 7-day water fasting period, your body’s electrolyte levels may become imbalanced due to the loss of fluids and minerals through urine and sweat. This imbalance can lead to symptoms such as fatigue, headaches, nausea, and other issues that may disrupt your fasting schedule and make it more challenging to fall asleep at night.

We’ll look into tips to mitigate these symptoms in the upcoming section of the article.

May affect the quality of your sleep

A 7-day water fast may impact your sleep quality because it can disrupt the body’s circadian rhythm. This internal biological clock regulates sleep-wake cycles, and any disruption can result in insomnia and difficulty sleeping.

Additionally, fasting can cause stress hormone levels, including cortisol, to rise, which may further disrupt your normal sleep-wake cycle.

Dehydration or electrolyte imbalances during the fast can also lead to weakness, exhaustion, and muscle cramps, all of which can interfere with your sleep.

Fortunately, there are strategies you can employ to minimize the likelihood of experiencing these adverse effects.

Take a
1-minute quiz

and discover how much weight you can lose with DoFasting!

Tips for a Successful 7-Day Fast

Fasting for prolonged periods may have some uncomfortable side effects, but that doesn’t mean that following this eating pattern is an impossible task. Here are the 7 ultimate tips to help you complete your 7-day water fasting period.

Choose your timing wisely

Choosing the right time for your water fast is crucial, as minimizing distractions can help you stay focused on your goal. Select a week without dinner parties, social gatherings, or any events that involve tempting food.

Your concentration might also be affected during the fast, so it’s best to avoid scheduling major work presentations or critical tasks during this time.

If you’re a woman, avoid fasting during your period and refrain from water fasting the week before it begins, since cravings can be exceptionally hard to overcome.

Eat enough food before you start fasting

Eating whole, well-balanced meals rich in vitamins and minerals can help you prevent nutrient deficiencies during or after your 7-day water fasting period.

This approach also ensures that your body has sufficient energy reserves to rely on during the fast. Consuming adequate food can help stave off symptoms of weakness or lightheadedness that might emerge when the body is undernourished.

To effectively plan your meals before starting the water fast, you can use the DoFasting app. This app offers approximately 5000 different well-balanced and nutritious meal recipes for you to choose from, including meals under 10 minutes, stews, salads, pasta, soups, and more.

Additionally, DoFasting allows you to easily track your nutrition: simply select a meal or ingredient from the list, and the app will incorporate it into your daily meal plan, complete with a calorie count.

Stay hydrated with calorie-free liquids

Staying hydrated can help suppress hunger and avoid headaches, dizziness, and other side effects. The National Academies of Sciences, Engineering, and Medicine of the United States found that the appropriate daily water consumption is:

  • About 15.5 cups (3.7 liters) of fluids a day for men
  • About 11.5 cups (2.7 liters) of fluids a day for women

You can monitor your hydration level by observing your urine color. A pale yellow indicates you are well-hydrated, while dark yellow or amber may suggest dehydration.

You can use the DoFasting app‘s water tracking tool to track your water intake. Simply input the glasses or bottles of water you consume, and the app will calculate how much more you need.

Remember that during this kind of fast, you should only consume calorie-free drinks such as water, green tea, or black coffee.

Take supplements to replace lost electrolytes

An electrolyte imbalance can result in a variety of unpleasant side effects. As mentioned before, electrolytes, which are minerals that dissolve in the body’s fluids, are necessary for maintaining adequate fluid balance, muscle and neuron function, and heart health.

To prevent electrolyte imbalances before and during a fast, consider consuming electrolyte-rich fluids such as coconut water or sports drinks, or taking electrolyte supplements. These can help ensure your body receives the minerals it needs to function optimally.

In addition to electrolyte supplementation, consider taking nutritional supplements to support overall health during fasting.

Meditate to cope with possible food cravings

Water fasting requires abstaining from food for a week, which can understandably lead to intense hunger.

Meditation can help clear your mind of thoughts about food and provide a sense of calm before bedtime or in the morning as you start your day. Establishing a meditation routine can be beneficial for self-control.

Find a quiet space, sit in a comfortable position, close your eyes, and begin meditating. If cravings become too intense and meditation doesn’t help, there are other options to consider.

For instance, the DoFasting appetite suppressant is a fiber complex containing glucomannan and cellulose. This science-backed product is specifically designed to help curb cravings during your fasting period.

Get back into your eating window light meals

After 7 days of fasting, it is essential to reintroduce food gently to your body to avoid overeating. Begin with light meals, such as soups, salads, and fruits, which can help ease the transition back to regular eating.

Eating lighter meals can also help prevent digestive issues or stomach upset. Opt for easily digestible foods to smoothly reactivate your digestive system and minimize discomfort. You can use the DoFasting app to plan your meals, explore recipes, and ensure you are prepared for when the fasting period ends.

Take a
1-minute quiz

and discover how much weight you can lose with DoFasting!

7-Day Fast: Final Thoughts

A 7-day water fast is an intense fasting experience that lasts for a week, and some individuals may find it challenging to complete.

This type of fast can offer numerous benefits, such as improving cellular health, balancing insulin and blood sugar levels, and promoting weight and fat loss.

However, this eating pattern also has certain drawbacks. If you haven’t abstained from food before, it is advisable to try other more manageable intermittent fasting styles first.


Profile Picture
DoFasting Editorial
Leave a comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Please note, comments must be approved before they are published

See how DoFasting will improve your life

Find out what works for you with this 60-sec quiz approved by our experts and get your personal revolutionary fasting assistant.

Start the Quiz

This is an evidence-based article that includes scientific citations. DoFasting’s professional writers and editors prepared the content, which a team of medical experts verified to be accurate.

Take a 1-minute quiz and discover how much weight you can lose with DoFasting!
Start the quiz