Fasting has been a part of human existence since the beginning of time, the abundance of food in our modern society has made fasting out of necessity a thing of the past. In recent years, however, the concept of fasting has become more common. This is your quick guide to fasting, which will answer the basic questions of who, what, when, and how fasting may be beneficial (not necessarily in that order).


Quick guide to fasting – what is fasting?

By definition, fasting is the absence of eating. You fast daily from the time you eat your last food or drink in the evening to the time you consume your first food or drink in the morning. These hours are your “fasting window,” as it’s often referred to.

Ideally this fasting window would be at least 12 hours. This allows time for adequate digestion, decrease in insulin response to food, and quite frankly gives you fewer hours for calorie consumption.

Just to be clear, there are some common misconceptions to this. You are still fasting as long as your body doesn’t have to break anything down. No carbs, protein, fat. What you can have that still is considered fasting includes water, sparkling water, black coffee and tea, or broth. These may keep you hydrated and some provide some trace amounts of sodium that can be beneficial.

Who benefits from fasting?

In the research, fasting is beneficial for several categories of people. If you have any of these conditions you may benefit from fasting:

  • metabolic dysfunction – prediabetes, type 2 diabetes, polycystic ovarian syndrome, and insulin resistance
  • if you are trying to lose weight
  • improve heart health
  • decrease inflammation
  • fasting can be useful during chemotherapy treatments for some cancer
  • improve mental clarity
  • increase energy
  • prevent Alzheimer’s disease
  • reverse the process of aging

There are categories of people which fasting is not beneficial. Fasting is not recommended if you are pregnant or nursing, are under the age of 18 years old, are underweight or malnourished. Also if you have struggled with disordered eating patterns or have a history an eating disorder fasting is contraindicated.

Some questions remain about the benefits of fasting. Much of the research does not differentiate the difference in the benefits of men versus women. Additionally, there is no specific research for women if you are pre-menopausal, perimenopausal, or postmenopausal. Additionally, if you have thyroid or adrenal dysfunction the physiological stress of fasting may not work in your favor.

How do you set up a fasting routine?

There are various way that you can set up a fasting routine. A few things to remember – aside from your daily fasting of 12 hours – there are multiple ways to fast, none of which are right or wrong. Here are three options that may work best for you.

Intermittent fasting

This identifies hours as fasting window : eating window. These can be done with varying times.  Some common windows are 12:12 (12 hours of fasting: 12 hours of eating), which is a very basic fast. A more common fasting method is 16:8 (16 hours of fasting: 8 hours of eating), which is often referred to as time restricted eating. Lastly 20:4 is a much more restricted eating pattern. These can be varied. It’s actually beneficial to change up your fasting pattern.

Fasting mimicking diet – 3-5 day pattern

The fasting mimicking diet was started by Dr. Valter Longo, an Italian cell biologist and biogerontologist. It is based on the concept of fasting, however you can still eat, some, during the fasting window. This pattern mimics fasting by significantly decreasing your intake during your fasting time period. This fasting time is longer and typically designed for to last five days.

During fasting mimicking diet, the intake is decreased to 1090 calories for the first day, then 725 calories on the remaining days. Your body goes into a fat burning and cell “cleanup” phase. While the original fasting mimicking diet is designed for 5 days, you can still get benefits doing it for shorter periods of time, anywhere from 3-5 days.

In order to get the full metabolic benefit, this pattern should be repeated once per month for three to six months.

Fasting mimicking diet  – 5:2 pattern

Okay, so this pattern is not officially considered the fasting mimicking diet. This pattern would allow for fasting for two non-consecutive days per week. On the other five days you would continue with your usual, nutrition-based eating pattern. This allow you to introduce yourself to fasting and possibly transition to another form of fasting.

The biggest mistake with fasting

Since fasting is the absence of eating, many times there is a very common mistake that is made with regard to your drinks. As a reminder, fasting includes anything that your digestive system doesn’t have to break down. The most common mistake made is skipping breakfast, but continuing your coffee ritual. While black coffee keeps you fasting, as soon as you add any sweetener (even one without calories), coffee cream, or powdered coffee cream, you are breaking your fast. Even if you are not eating.

This guide to fasting provides you with knowledge about some basic ways to start a fasting routine for yourself.

Have you ever fasted? If so, how did it work for you?