What is a 168 hour fast?
A 168 hour fast, also known as a 7 day fast, involves not eating any food for an entire week. This means going without any calories from food for 168 consecutive hours. During this time, you can only consume water, black coffee, tea, and other zero-calorie beverages.
Some people do this type of prolonged fast for health or weight loss reasons. Proponents claim that an extended fast gives the digestive system a rest, triggers autophagy (the body’s self-cleaning process), and prompts the body to burn through glucose and start accessing fat stores for energy.
Is it safe to fast for 168 hours?
Fasting for a full week without supervision can be dangerous for some people. Potential risks include:
- Severe hunger and food cravings
- Fatigue, dizziness, headaches
- Electrolyte imbalances
- Dehydration
- Nutrient deficiencies
- Gallstones
- Irregular heartbeat
- Fainting
Prolonged fasting may also be unsafe for people with:
- Diabetes
- Eating disorders
- Gastrointestinal issues
- History of disordered eating
- Malnutrition
- Pregnancy or breastfeeding
If you have any underlying health conditions, it’s important to talk to your healthcare provider before attempting an extended fast.
What are the benefits of a 168 hour fast?
Some potential benefits of fasting for 168 hours include:
- Weight loss – Going a full week without food generally leads to a significant calorie deficit and weight loss, provided you don’t drastically overeat when you finish fasting.
- Reduced inflammation – Fasting may decrease markers of inflammation like c-reactive protein (CRP).
- Lowered disease risk – Animal studies link prolonged fasting with a reduced risk of some cancers and autoimmune disorders. More human research is needed.
- Heart health – Fasting significantly improves cardiovascular risk factors like blood pressure, total cholesterol, triglycerides, and fasting glucose.
- Increased longevity – Research shows fasting can extend lifespan in rats and mice. The effects on longevity in humans remain unclear.
According to some small studies, longer fasts may be more effective than intermittent fasting or short fasts for achieving certain benefits like improved insulin sensitivity. However, more research is still needed.
What are the risks of a 168 hour fast?
Despite some potential benefits, prolonged fasting comes with several risks:
- Nutrient deficiencies – Going a full week without nutrients can lead to temporary deficiencies in vitamins, minerals, protein, essential fats, and more.
- Muscle loss – Fasting for 168 hours is likely to cause some loss of lean muscle mass as your body breaks down protein stores to make glucose.
- Binge eating – Some people overeat when they finish an extended fast, which can undermine weight loss efforts and have negative health effects.
- Electrolyte imbalances – Low sodium, potassium, magnesium, and other electrolytes can cause side effects like fatigue, muscle cramps, dizziness, and abnormal heart rhythms.
- Dehydration – It’s easy to become dehydrated when fasting for a week, especially if you’re being physically active.
- Gallstones – Rapid weight loss from fasting can increase your risk of developing painful gallstones.
- Digestive issues – Breaking a long fast can disrupt digestion and cause diarrhea, bloating, cramping, and nausea.
The risks tend to be higher if you have certain pre-existing medical conditions. Fasting for a week or longer should only be done with medical supervision.
What does science say about 7 day fasting?
Here is what the research has found so far on fasting for 168 hours or longer:
Animal studies
Studies in rodents and other lab animals have found prolonged fasting may:
- Extend lifespan
- Improve insulin sensitivity and glucose metabolism
- Enhance cardiovascular health
- Stimulate autophagy
- Reduce inflammation
- Have anti-cancer effects
However, results in animals do not always translate well to humans. More research is needed.
Human studies
Small clinical studies in humans suggest 7-day fasting may:
- Lead to 7-9% weight loss
- Lower blood pressure
- Reduce oxidative stress
- Decrease markers of inflammation like CRP
- Improve asthma symptoms in overweight people
Larger, longer-term human studies are still lacking. Potential health risks like muscle loss, nutrient deficiencies, gallstone formation, and disordered eating patterns also need further investigation.
Expert opinions
Most mainstream dietitians and healthcare providers recommend against prolonged fasting without medical supervision. Potential benefits tend to be small and transient, while risks may be severe or even life-threatening in vulnerable populations.
However, some fasting advocates believe the benefits outweigh the risks for most relatively healthy people. Proper refeeding practices can help prevent issues like binge eating when the fast is over. Electrolyte supplementation may reduce side effects.
But experts agree more rigorous, large-scale human research on extended fasting is still needed.
Should you fast for 168 hours?
Here are some things to consider if you’re thinking about doing a 168 hour fast:
- Talk to your doctor first, especially if you have any medical conditions or take medications.
- Consider your health history – prolonged fasting is riskier for people with a history of disordered eating.
- Try shorter fasts first to see how your body responds.
- Stay hydrated by drinking water, herbal tea, broth, etc.
- Supplement with electrolytes if you start feeling lightheaded or fatigued.
- Break your fast slowly and mindfully – don’t binge.
- Focus on nutritious whole foods when you start eating again.
- Listen to your body’s cues and stop fasting if you feel unwell.
168 hour fasting is not for everyone or even most people. You may get similar benefits from intermittent fasting a few days per week or trying occasional 24-48 hour fasts. Higher risk individuals should focus on safer weight loss strategies like improving their diet quality and exercising more.
Should you do a 168 hour fast every day?
Fasting without food every single day is an extreme practice that comes with substantial risks:
- Increased malnutrition as vital nutrients are missing from your diet.
- Greater loss of muscle mass and strength.
- Higher likelihood of refeeding syndrome when breaking the fast.
- Severe electrolyte imbalances.
- Greater impact on hormone levels.
- Higher risk of gallstones.
- Increased tendency for binge eating.
- More severe effects of dehydration.
- Greater burden on your liver to produce glucose.
- Higher chance of fainting.
Going a full week without food is physiologically stressful. Doing it every day may lead to chronic health problems.
Research has not looked at the effects of 7 day fasting periods back-to-back for weeks or months. However, experts warn against such an extreme dietary practice.
Your body needs essential proteins, fats, vitamins, and minerals from food to function properly. Taking in zero calories for days on end does not seem to be a sustainable, healthy lifestyle for most people.
If you are looking to improve your metabolic health, lose weight, or achieve other benefits, there are safer fasting protocols to consider. Many people find success with intermittent fasting just 1-3 days per week. Or you could try occasional 24-72 hour fasts each month.
speak with your healthcare provider to develop a fasting routine that is safe and appropriate for your situation. Avoid prolonged periods of zero calorie intake unless medically supervised.
Conclusion
In summary, 168 hour or 7 day fasting is an extreme intervention that may offer some benefits, but also carries significant health risks. More research is still needed on the long-term effects in humans.
While occasional 168 hour fasting periods done carefully may be well tolerated by some relatively healthy people, regularly fasting for a full week does not appear advisable or sustainable for most. Instead of daily prolonged fasting, safer alternatives like intermittent fasting or 24-48 hour fasts every so often are likely to provide health benefits without as many risks.
As with any major dietary change, be sure to consult your healthcare provider before attempting prolonged fasting. Very low calorie intakes for days on end could be dangerous without medical supervision, especially for those with certain pre-existing conditions or a history of disordered eating.