Alternate Day Fasting (ADF)

Eat one day, fast the next day. It’s basically that simple and doesn’t get any easier. Imagine finishing dinner today and not eating anything until the day after tomorrow. Gosh, you just have to become hangry, don’t you? There’s just no way that you’ll be going to bed fasted, waking up the next morning without blinding headaches and the strong urge to kill for food. No, no way, right? The funny thing here is, it’s the complete opposite. Most of the time, you won’t feel hunger at all and be constantly focussed as hell. Don’t believe me? Then let me get a little more scientific here.

After fasting for approximately 24–36 hours, your liver glycogen stores have run out and as a result, your body starts producing new glucose from amino acids in a process called gluconeogenesis. At the same time, insulin (a hormone which is usually increased when you eat and serves as a signal for your body to store some of the excess food energy as fat for later use) gets lower. Now, if insulin levels are low enough, lypolysis sets in which results in your body using fat for energy production. Basically, your body starts to eat up itself, but in a good way, getting rid of body fat. It’s also clear that a state of low-insulin in our bodies not only helps with fighting off type-2-diabetes and regaining insulin sensitivity, but also gives our body the needed time to burn off its own fat stores while blunting any hunger pangs by reducing ghrelin, our body’s hunger hormone. Eventually, ketone bodies are produced which are used by the brain for energy usually resulting in a feeling of mental clarity and higher focus throughout the day.

Contrary to popular belief, fasting for a couple of days doesn’t even slow down your metabolism, but can rather boost it up by up to 14 percent. In fact, it’s because your body starts to produce more adrenaline which is used to release all of the stored glycogen. That process eventuates in you feeling fairly energized and therefore stimulates the metabolism, too.

Finally convinced by the facts? Then give it a try, fast for at least 36 hours and see it for yourself. If you’re more adventurous and not feel hungry which you most likely won’t be as we’ve just learned, you could extend the fasting period until lunch or even dinner. Usually, it really helps when you fast at least until midday, so you’re able to eat bigger portions at the second part of the day. It also helps you to feel fuller after finishing your bigger meals.

Interestingly enough, it seems that most of the current scientific findings even stemmed from a slightly modified way of alternate day fasting where test subjects were allowed to eat 500 kcal on fasting days. Something like that is usually called a fasting mimicking diet which is an attempt to maximize the benefits of caloric restriction while minimizing the downsides.

Be aware though that you have to stick to only drinking water during your fast if you want to gain all the benefits of autophagy, a mechanism in your body which helps to recycle certain cell components and gets rid of unneccessary and dysfunctional cells by apoptosis. Apparently, drinking anything else than water still requires digestive enzymes for your body to process, so technically, it would break a fast. However, if black coffee, herbal tea or bone broth make fasting more enjoyable for you, definitely stick to them. Just pay attention not to steep your tea for too long because the tannins in tea can make you feel nauseated on an empty stomach. Moreover, add some salt to your drinks if you start feeling dizzy or light-headed during your longer fast.

Time-Restricted Feeding (TRF)

Fast for 14–23 hours and just eat during a specific feeding window. That’s it. Unfortunately, most of the previously mentioned benefits of fasting only apply to longer periods of abstinence from food. However, shorter fasting periods have been also shown to increase HGH (human growth hormone) which helps to preserve muscle mass, but won’t really increase stem cell production or allow for the clearing away of damaged cells as you’ll see with prolonged fasting due to autophagy. Yes, THE growth hormone which you can also find in mother’s milk and bodybuilders usually love to use in *cough* appropriate manners. Did you also know that intermittent fasting can increase brain-derived neurotrophic factor (BNDF) which grows new neurons in your brain?

If you want to dive deeper into the beautiful world of fasting, you should definitely check out the work of Dr. Valter Longo, Dr. Jason Fung, Dr. Satchin Panda and Dr. Krista Varady. Brad Pilon also offers excellent information about the topic. These are the leading researchers in the scientific field of fasting and will help you understand the impact fasting has on health, well-being, cognition, longevity, cancer cells, metabolism and more.