Intermittent fasting (IF) is an eating pattern that cycles between periods of Fasting and Eating. I.F protocols are primarily based around the “eating window”, which then puts your body into large periods of fasting and this has powerful metabolic and biochemical effects within the body.
Fasting has been a practice throughout human evolution. Ancient hunter-gatherers didn’t have access to readily available food sources, as we have today. Many times they didn’t even find anything to eat for days together. As a result, humans have naturally evolved to function without food for extended periods of time. Fasting from time to time is more natural than always eating 3-4 (or more) meals per day. Fasting is also commonly followed by certain religions.
Several things happen at the cellular level that causes hunger and fatigue during the initial stage of fasting. When you are eating regularly, your body breaks down glucose to get the energy it needs to function properly. While you are fasting, your body needs to produce glucose to get the energy, so it begins a process called gluconeogenesis. During gluconeogenesis, your liver converts non-carbohydrate materials like lactate, amino acids, and fats into glucose. At this stage, you may feel drained but you will regain your energy soon.
When you consume a typical diet of carbohydrates rich foods, your body breaks down sugars and starches into glucose. However, when you fast or go into ketosis, availability of glucose becomes limited, and your body must turn to fat stores for energy. Your body fat breaks down to glycerol and fatty acids. The liver synthesizes ketones using glycerol. The glycerol is broken down by the liver for additional glucose, and finally, those ketones are used by your brain as glucose becomes less available.
There are many studies on intermittent fasting, in both animals and humans. These studies have shown that it can have powerful benefits for weight control and health of your body and brain. Intermittent fasting is also said to be helpful in reducing the risk of type 2 diabetes, one of the biggest killers of modern society. It is believed that it may even help one live longer.
Following are some established benefits of Intermittent Fasting:
The 16/8 Method means fasting every day for 14-16 hours and restricting daily eating window to 8 hours. You can include 2, 3 or more meals within this eating window. This is also known as the LeanGains protocol and was popularized by fitness expert Martin Berkhan. This is said to be the easiest approach for following Intermittent Fasting as it can be as simple as skipping breakfast directly having lunch after 12 noon and getting done with your dinner by 8 pm. So, technically it will be fasting for 16 hours from your last meal of the day to the first meal of the next day. It is generally recommended for women to fast only for 14-15 hours because they seem to do better with slightly shorter fasts. You can drink water, coffee and other non-caloric beverages during the fast; it will also help reduce hunger levels. It is very important not to include junk food or excessive amounts of calories.
Eat-Stop-Eat means a 24-hour fast, either once or twice per week. This method was popularized by Brad Pilon and has been quite popular for a few years. Water, coffee and other non-caloric beverages are allowed during the fast, but no solid food.
The problem with this method is that a full 24-hour fast can be fairly difficult for many people.
Alternate-Day fasting is a planned method where you fast or starve for 24hours followed by 24 hours of normal eating without binging on food. There are different versions of it where some allow 500 calories on the days of fasting where others stick to non-caloric beverages. Alternate-Day Fasting seems to be a bit unsustainable in the long run as becomes difficult to go to bed hungry for several times in a week.
It involves eating small amounts of raw fruits and vegetables during the day, then eating one huge meal at night. Here you fast whole day and feast during a 4-hour window at night. It is all about eating small amounts of vegetables and fruits during the day and then eating one huge meal at night. Warrior Diet was the first popular “diets” to include a form of intermittent fasting. It was popularized by fitness expert Ori Hofmekler. Food choices in this diet are quite similar to paleo diet i.e. unprocessed, whole, natural food sources.
Type of Intermittent
Star rating in terms
of fat burning
4 pm - 9 pm
9 pm - 4 am
4 am to 12 pm
( 8 hours a day)
(Day 1,3,5,7 will be Feasting days and
Day 3,4,6 will be Fasting days)
8 am - 1 pm
1 pm - 8 pm
8 pm - 8 am
(12 hours each day,
3 days a week)
8 pm - 11 pm
11 pm - 8 am
8 am - 12 pm
(4 hours a day)
Eat/ Shop/ Eat -
One day a week fast
8 am - 11 am
11 am - 8 pm
8 pm - 8 am
(one day a week)
*Fed State – Starts when you begin eating, lasts till 3-5 hours
*Post Absorptive state – It is 8-12 hours after the last meal, in this state body is not processing a meal
*Fasting state – Natural fat burning state, it is 12 hours after the last meal
Intermittent Fasting has an outstanding safety profile. There is nothing dangerous about not eating for a while if you are healthy and well-nourished overall. However, if you belong to any of the following categories, you should consult a physician before considering intermittent fasting :
The ideal form of Intermittent Fasting would be when combined with Nutritional Ketosis (NK) to help reduce inflammation and burn body fat. Which protocol you choose from the ones mentioned above would depend on your lifestyle, fitness goals and general metabolic condition. All said, with hundreds of thousands of people taking to I.F across the world, one thing is for sure; Intermittent Fasting is not a fad diet. It is here to stay.