I come from the school of "if you don't eat, your muscle deteriorates and you'll lose it." Thus, fasting has always been out of the question until I saw a few industry leaders that I really respect trying it - so I gave it a chance.
When I came to understand the convenience and cognitive benefits - it became less weird and more practical to me. Fasting has been around for centuries in different forms. Humans are built to be able to go long periods without eating because of our ancestry. We used to hunt for food, eat a relatively big feast - then not eat until the next day. Food was not always readily available at Whole Foods, Safeway and Trader Joes (crazy, right?).
What really hooked me was the cognitive benefits. I experienced a laser focus throughout my morning fast. My longest fast was 40 hours, but we'll talk about that another time. Today our focus is a traditional intermittent fast in which you abstain from eating for 16 hours, and eat for 8.
Preface: I know what you're thinking and the answer is no. Fasting does not magically make you lose weight. Weight loss is, at its simplest form, a byproduct of eating LESS calories than you BURN on a daily basis consistently. Fasting and being in a caloric deficit do not NECESSARILY go hand in hand. You can still crush a pizza and be in a caloric surplus during a fast. If you are looking to use this for weight loss - eat less than you burn and eat real foods as much as possible.
Intermittent Fasting Fundamentals:
Don't eat for 16 hours, then eat for 8.
Eat real foods. This is NOT an escape route to eat fast food, high sugar, fat or carb diets.
Drink lots of water, .75 oz per body pound.
Have Pink Himalayan Sea Salt on hand. Most people can go 16 hours without needing electrolytes (salt), but if you feel low energy - put a pinch of Sea Salt under your tongue. If you continue to feel fatigued - eat a small balanced meal.
Your first meal should be a balanced meal of: complex carbohydrates, lean protein, lots of greens and a small amount of fat. You may feel tempted to eat the entire kitchen as you come out of the fast - DONT. Make a normal sized plate, eat that plate - then move on. Over-eating as you break the fast will put you into a hazy food coma state that is the complete opposite of our mission here.
Intermittent Fasting and Your Workouts:
If you workout during a fast, take a BCAA supplement intra-workout. BCAA's help repair muscle after we break them down during a workout.
Best practice: Finish your workout before hour 12-14, otherwise you may feel extremely fatigued during your workout.
More About My Experience:
I found it easiest to stop eating at 5 PM and continue to eat 9 AM the next day. It seemed pretty easy because I was sleeping for 7 out of the 16 hours and working for another 6.
A benefit of fasting that I did not anticipate was convenience. Thinking less about constantly packing food (I eat 4 meals per day + 2 shakes) was a nice break. When I woke up at 4:30 AM, I could roll out of bed, drink a cup of water and get to the gym to do what I love. When I got home, I was able to spend more quality time with my Fiancé.
What really made this stick was the cognitive benefits. I'm on a constant mission to feel and perform my best at work. The mental clarity I experienced was unmatched. I was able to be focused all the way to the end of the fast and sometimes even beyond the normal 16 hour window if other things came up. If you're wondering why I stopped - I'm currently training for a powerlifting meet and eating to gain weight. 8 hours simply is not enough time for me to get the amount of calories in that I need to put mass on. I do intend to go back to Intermittent Fasting once my meet is over in May. At the moment I go by feel and use IF 1x or 2x per week on my off days or days, or when I feel really slow from eating in a caloric surplus OR when my morning is slammed and there is no time to eat.
I hope this helped clarify how to use IF. Let me know if you have ANY questions.