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Fast Facts & FAQS: Frequently asked questions about Fasting


Frequently Asked Questions About Fasting

  1. What is Fasting?

    According to the dictionary, fasting is abstaining from all or some kinds of food or drink. But more accurately, fasting is a tool that can help you tap into your body’s innate healing and fat-burning potential by selectively refraining from caloric-food or drinks either part or all of the day. 

  2. What Does Science Say About Fasting?

    Whether you try intermittent fasting, 24-hour fasts, or prolonged fasts, the science is overwhelmingly in favor of most fasting practices. Research indicates that fasting improves 
    • arterial health
    • cognitive health
    • digestive health
    • longevity
    • DNA
    • body composition
    • sleep quality and duration
    • and numerous other aspects of health.
Many of the benefits of fasting come from the cellular clean-up process known as autophagy. Science shows that this process reduces inflammation, increases immunity, and is even important for fighting cancer.


  1. Is Fasting A Diet or a Lifestyle?

    Doctors regard most fasting methods as lifestyle changes – not a diets. When you practice intermittent fasting, there are no limits as to what type of foods you can eat, and you can eat as much or as little as you need to during your eating window. (Active people usually have to eat more, and sedentary people are advised not to overeat on any fasting protocol.)

    That said, most people tend to eat fewer calories while fasting as a lifestyle.


  1. What are the Most Popular Fasting Methods

    Researchers have focused mainly on alternate day fasts (also called Eat-Stop-Eat) and Time Restricted Eating. But the 16/8 method, the 5:2 method, and the fasting-mimicking diet are popularly used for weight loss and health gains.

    What’s the best fasting method? That depends on your current state of health, your activity levels, and your calorie needs. Make sure to consult your doctor to see which one is right for you.
  • Heart problems
  • Liver or kidney insufficiency
  • Epilepsy
  • Pregnancy or breast-feeding
  • Eating disorders
  • Hypothyroidism

  • Is Fasting Safe?

    Fasting has been part of every human culture and religion since time immemorial and is generally recognized by the medical establishment as being safe. There have even been yearlong fasts (doctor-supervised, of course) that were not found to be damaging in any way!

    But there are certain conditions that people should always check in with their doctors before attempting fasts of any kind:

  • What Are The Benefits of Fasting

    The benefits of fasting are many and multi-faceted. As for health, you can expect increased energy, a better physique, a better relationship with food, better immunity, greater cancer-fighting ability, improved coordination, better mood, and enhanced digestion. (This list could go on for days!)

    But the benefits of fasting aren’t limited to the body. Many religions have used fasting as a way to improve people’s spiritual lives and inner peace. And many workers have found their lives to be more focused and less distracted when they aren’t constantly eating.
    1. What are the Risks of Fasting?

      Though fasting does have potential dangers, these risks are mostly limited to people who are sick, undernourished, and who have eating disorders. (Remember, we all practice some level of fasting every time we sleep or go without food!) Read on to find out what risks are possible when fasting: 
      • Prolonged fasts of three days and up have been linked to refeeding syndrome — a dangerous electrolyte/fluid imbalance. But this most often occurs in people who are severely malnourished.
      • Pregnant women aren’t advised to practice fasting because of potential pregnancy complications.
      • Dehydration can occur while fasting. People who fast need to consume more water than usual, because food alone can account for 20-30% of total fluid intake.
      • Headaches are a very slight but common issue at first.
      • Eating disorders can be magnified in those with anorexia or bulimia.
      • Electrolyte imbalances can happen if you go too long without enough minerals – which could lead to dizziness, heart palpitations, and feeling weak. (Doctors recommend taking a multi-mineral tablet and/or adding salt to water during longer fasts.)
      • Hunger is a standard risk for all fasters. But it doesn’t last! Studies actually report less overall hunger when participants adhere to an IF practice.
    1. What to Expect During A Fast

      People who’ve never fasted typically experience very mild and brief periods of discomfort, ranging from gnawing hunger to headaches, irritation, and low energy. But if you stay busy and hydrated, you, like many others, may find that your fasting periods are happier and more productive than when you’re eating!

      The most basic form of fasting involves nothing more than an early dinner or a late breakfast, which may be nothing to you at all. As you attempt longer fasts, your relationship with food will be challenged. You’ll have to be mindful in assessing whether the feelings you’re experiencing are actual hunger, thirst, or a need for fulfillment.
    1. Can I Gain Muscle Mass While Fasting?

      It’s a popular misconception that you can’t build muscle while fasting, but studies show that muscle growth happens at the same rate for both fasters and non-fasters. Why? Simply put, most people aren’t actually starving themselves during a fast. Even when muscle is being used for fuel mid-fast, your body preferentially selects damaged or old muscle tissue that your body would function better without. Improved insulin sensitivity makes it easier for your body to store calories as muscle, too.
    1. How Long Should I Do Intermittent Fasting?
    Humans have evolved under periods of food shortage, both acute and prolonged. This means that our bodies are equipped for intermittent fasting (IF). (Many studies indicate that we’re healthier when fasting regularly.)
    You should always consult your doctor before making major dietary or lifestyle change. But you can (and should!) practice intermittent fasting for as long as you feel good doing so. Doctors are approaching IF not as a short term dietary intervention, but as a long-term way of life.


    1. Will Fasting Help Me Reach Ketosis?

      During prolonged fasts – over 24 hours – the body briefly breaks down muscle for ketones, then quickly crosses over to fat-based ketone production. The transition to fat-based ketosis happens more quickly as you become adapted to fasting.

      But even during shorter fasts or intermittent fasts, your body is being conditioned to use fat for fuel (ketones) when you don’t have access to carbs and other sources of energy – especially when you exercise.


    1. How Does Fasting Help Me Lose Weight?

    There isn’t just one way that fasting helps you lose weight, but we’ll start with the most obvious: you’re not eating. Studies show that calorie restriction is one of the most reliable ways to lose weight and keep it off, and that’s true whether you cut portions daily or fast weekly. Fasting also primes your metabolism to burn fat for fuel, which gives you energy and focus without the daily carb cravings. Last but not least, fasting improves insulin sensitivity – this helps you lose weight in several ways.


    1. Discover What Experts Are Saying About Fasting

      David Perlmutter, author of ‘Brain Maker’: “Fasting is baked into our evolution and our physiology and it can yield benefits to our brains and bodies, at a biochemical level, that we’re only just beginning to understand.”

      Dr. Peter Osborne, author of ‘No Grain, No Pain’: “It’s of the cheapest and easiest health tools you can access. Fasting has been shown to be beneficial for a variety of different diseases and health problems including rheumatic diseases, chronic pain syndromes, hypertension, and metabolic syndrome, obesity, cancer, digestive disorders, and more

      Dr. Rhonda Patrick, Ph.D. health researcher: “Most people who practice fasting report feeling energized and more alert at the end of their fast, which may represent a “resetting” of their body’s natural metabolic rhythms.”

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