Intermittent Fasting is the latest hype in the diet and nutrition world. Intermittent fasting has many benefits which are scientifically proven. I still use intermittent fasting only in a few specific cases and only certain types of intermittent fasting. This article gives an overview of the why and how.
What is intermittent fasting?
Intermittent fasting (IF), is an umbrella term for various diets that cycle between a period of fasting and non-fasting during a defined period.
Different variations of intermittent fasting
There are different versions of intermittent fasting. The first hype in the fitness industry started over 10 years with the release of the Warrior Diet book. This initial system called for one meal per day plus some <100 kcal snacks throughout the day. This system worked well for some. In the last years the system of 8-16 has risen to popularity. That means you fast for 16 hours and eat for 8 hours. Sounds reasonable. In the end its just canceling breakfast though. 8-16 means on starts eating between 12 and 14 then stops between 20 and 22. That is just skipping breakfast.
Intermittent Fasting & Breakfast
As pointed out the 8-16 intermittent fast is mostly just breakfast canceling. Does it still have some effects, yes. Just creating awareness for something, in this case eating will have some level of benefit. Looking at this from a birds view though, how many people skip breakfast all the time, and how well do they do with that. Many and not very well are the statistically correct answers. Breakfast is actually the most important meal of the day as it effects energy level, hormones and neurochemistry for the rest of the day. Breakfast is the first meal I address and improve first with every client and athlete that works with me. I have written on my base view on breakfast in the article " Eat animal for breakfast " and " Wake up early and have a good breakfast to feel better ".
The Downsides of Intermittent Fasting
Why don't I recommend Intermittent Fasting more often? Intermittent fasting is a diet system that only addresses one aspect of food which is its timing. Which makes it a very one dimensional approach. In short, there are three major downsides of intermittent fasting:
1. Its too one dimensional - First, there is much more to nutrition than timing. Doing intermittent fasting on pasta and pizza is intermittent fasting yet it will have its obvious drawbacks just on food choice. A calorie is not a calorie. Research and empirical evidence clearly points out that food choice and macro nutrient distribution do have a major influence.
2. Calorie restriction is only a short-term solution – Second, calorie restriction in this case through intermittent fasting works only short-term and only for certain goals. The Yo-Yo Effect is the most known downside of short-term solutions. As long-term sustainable change is the major goal, isn't an ideal long-term solution.
3. The Cortisol Cascade —Third, there are two major pathways that regulate blood sugar. Food and the endocrine system. When food is eliminated as a factor the endocrine system has to do the job, primarily via the release of cortisol. Which is only a short-term solution as hyper secretion of cortisol in frequency and intensity will lead to a cascade of negative feedback. I have cover this in my “ The Insulin Myth ” article in more detail.
Next to these downsides, there are still some upsides to intermittent fasting.
My take on intermittent fasting
I am neither a fan of the Warrior Diet nor of the 8-16 system and a calorie is not a calorie. Just based on the overall results one gets. There are other options for fasting that I would prefer such a low-frequency 6-18 intermittent fast or a functional fast like the green week that I talk about at the YPSI Module 4 Seminar .
Why intermittent fasting still works for some
Results are progress, so definitely see some going from a "standard diet" to an 8-16 system and improve. 5° is warmer than 0°, yet definitely not warm by any standards. The main question for everyone who wants to start Intermittent Fasting is: "What type of Intermittent Fasting shall I do to achieve results that I am interested in?". The following three considerations will put some light on this question.
Three Considerations for Intermittent Fasting
To circle back to the beginning of the article, intermittent fasting does have some benefits. When some starts on Intermittent Fasting there are three major considerations that need to be considered to make a good decision on the how and what of Intermittent Fasting:
1. Frequency of the fasting - In 2009 I have attended a seminar on cardiovascular health by Dr Mark Houston. One of the main takeaway points for myself wasn't related to cardiovascular health directly though. dr Houston mentioned a German study that looked at the frequency of fasting in its changes in effects. And the study showed that there are no benefits between intermittent fasting on 3 days a week and 7 days a week. So why almost 7 days a week when 3 days a week give you the same benefits?
2. The length of the fast - there are different lengths of fasting. The shortest thats common is a 12-12 fat, with 12h of eating followed by 12h fasting, which mathematically somewhere in the area of eating from 7 till 19, so basically just an early dinner. The longest intermittent fast would be only one meal per day. The most common is 8-16 these days. Different lengths of fasting have different advantages and disadvantages. The main advantages of fasting come from longer fasts. Yet, the longer the fast the higher the stress response to fasting. So, the sweet spot lies somewhere in between. Almost long enough to get benefits. Don't almost so long that the stress response diminishes the benefits. I see an 6-18 fast as the best solution for most when choosing a fast that brings the great advantages while minimizing the stress response.
3. Total nutrient intake – It is simple math, when one eats and digests food less hours per day, one will consume less nutrients per day. Consuming less nutrients can have benefits in some scenario, yet, consuming enough nutrients is major challenge in many scenarios and many clients that I see as a coach. Eating enough is a hurdle for the athletic population and clients that have rather serious goals. Many eat way too little to fuel recovery and supercompensation. With high training volume especially towards strength and hypertrophy goals the intake of a high amount of nutrients is crucial. If you want to build a big and strong house you need plenty of concrete.
To sum up my position, intermittent fasting does not equal intermittent fasting. Same as protein does not equal protein. And a calorie is not a calorie.
There are systems of intermittent fasting that do work well in certain scenarios and for specific goals. Modify the length and frequency of the fast. 6-18 works better than 8-16 for many as those 2 hours extra actually increase the time of the fasted state after the post-absorptive state which ends about 8 to 12 hours after the last meal quite a bit. Also consider the frequency of fasting. Why do it 7 days per week if 3 days per week get the same results? More is often not more. You are not deadlifting 7 days per week either as 1 to 2 deadlift sessions per week lead to much more progress and results.
In the end, pragmatism prevails. If it really works for you, do it. If it doesn't work, don't do it. Now figure out the if and what. In theory and practice.
All the Best with choosing the if and what of Intermittent Fasting!
Picture: An empty plate.