Intermittent Fasting

The purpose of todays blog is to breakdown intermittent fasting and to explain what it is, why use it, whos’ it for, what are the benefits and what are the different types.


So what is it?


Intermittent Fasting (IF) relates to any diet that cyclically restricts energy intake for a predetermined period of time. In other words, a person takes on a diet of time restricted feeding. There are many proposed physiological benefits to IF, however most of them are based on animal studies therefore may not be truly applicable to humans.


So why use it?


Simply put it is a more pleasant way for some people of creating an energy deficit in order to facilitate fat loss.


Who is it for and can anyone use it?


The two situations where IF should not be used are 1) when you are pregnant and 2) when it simple doesn’t suit your routine. Remember any diet needs to be sustainable to be successful. IF is not magic, it is just another way to create an energy deficit that some people like because it suits their goals and lifestyle.


Wrongly Placed Negativity


There is also some wrongly placed negativity surrounding IF for two main reasons. One of which is “skipping meals will put your body into starvation mode and you will gain weight.” This is a false statement. “There is no evidence that weight loss on hypoenergetic diets is altered by meal frequency.” Bellisle et al. (1997) Another is “breakfast is the most important meal of the day.” Also a false statement. “A recommendation to eat or skip breakfast had no discernible effect on weight loss in free-living adults who were attempting to lose weight” Dhurandhar et al. (2014)


Potential Danger


The main danger associated with IF is that it could conceivably be called “Meal Skipping” in many instances. However the idea of the “windowed eating protocol” is that you would aim to hit your target amount of calories as you would otherwise, just in a shorter space of time making it easier for you to manage. The issue can be that people would remove a meal or two and their calories would drop too low too quickly.


Unique Benefits


On the other hand, there are some potential unique benefits. The main two are with regards to constipation and appetite regulation. Many people will tell you they get disruption in their gut and with bowel movements when dieting. There seems to be some positive research that IF can help prevent this in a large portion of people.


 Also a period of abstaining from food intake may retrain habits or even physiological perceptions of hunger that may make a continued calorie reduced diet more sustainable. Often people can be afraid of hunger and at the first sign of it they reach for a snack when simply abstaining from food because of IF would lead to the feeling of hunger passing for another couple of hours.


Let’s talk about the different types


There are many but in this blog I’m going to concentrate on the 3 most commonly used. Alternate day fasting, 16:8 and 5:2.


Alternate day fasting is eat Monday, fast Tuesday, eat Wednesday, fast Thursday etc. This has been extensively used in particular with obese populations. As you can probably imagine people get very hungry but do lose weight if they can stick to it. Like a lot of diets this does seem only to be sustainable short-term.


16:8 which is the most popular. This consists of fasting for 16 hours including sleep and eating for 8. This is definitely shown to be more sustainable especially for those who are not habitual breakfast eaters. The 8 hour window can be whatever time of the day that suits you best. e.g between 10am-6pm or 12-pm-8pm.


5:2 is quite an interesting variation. It involves completing two very low calorie days per week with the other 5 being calorie controlled at your maintenance. The 2 very low calorie days can be any of the 7 week days but need to be low enough to create a deficit that will result in fat loss at the end of the week.


Summed up


At the end of the day all IF protocols are a means to achieve fat loss but will only be successful if they help you achieve a negative energy balance. For some they are helpful and one type may suit an individual much more than another. Choosing one over another should be based on the amount of fat loss needed to occur and the timeframe.


The alternate day fasting is clearly more restrictive the 16:8 version. Although there are a couple of unique benefits which I have gone through earlier I wouldn’t look at intermittent fasting much deeper than a means to create a calorie deficit overall. There are many different tools you can use to create this so be careful what you choose. The one that is most sustainable will inevitably be the best one for you. Everyone is different