It's no secret that there are some bold claims around Intermittent Fasting (IF). Much of it is bro-science, but there is also extensive research supporting it's use.
But the real question is, "Why on earth would you want to do it?"
Decades of research has high-lighted that sustained calorie under consumption (60 - 80% of daily intake) can have significant health benefits and can delay the onset of many age related diseases.
According to Harvard Education, prolonged very low calorie diets can cause physiological changes within your body that causes it to adapt to the reduction in calories, and preventing further weight loss from happening, so you'll want to use it intelligently.
How it works
Common methods consist of fasting on alternate days for the whole day (with a specific frequency per week), or during a set time frame (I chose the latter). Here are some examples,
How I did it
I opted for Time Restricted Feeding (TRF), simply because it is simple, easy to execute and fitted in with my lifestyle. I find the common mistake is people choose a version of IF that doesn't quite match their lifestyle, so they give up before achieving any of the benefits.
Initially my window for eating was 4pm - 9pm, I struggled to get my calorie intake of 3,170kcal - 3,635kcal, so I adjusted my time frame to
3pm - 9pm
Here's What I found..
Before I had started (IF) I had noticed my weight had crept up to 107kg, and I was not happy with the changes in my body, especially as the additional weight hadn't materialised into improvement in performance.
At competition I come in at 105kg and my usual walking around weight is 100kg - 103kg (a weight I naturally sit at when eating healthy and staying active).
I found the first 3 - 4 days extremely challenging, both mentally and physically. The hunger pangs were strong, and brain fog ensued as my body began to regulate my blood sugar levels through different mechanisms.
But I began to enjoy the mental challenge, feeling a sense of achievement knowing I had the discipline to do it despite the mental and physical discomfort. Also the physical hunger reminded me of my boxing days, and tapped into that mentality. My mind soon became sharper and as the days went on, it was these times of fasting that were my most productive work wise.
I adjusted my eating window so that I could get sufficient calories in, as prior to that it was a struggle. Unlike most forms of IF I didn't aim to restrict my calories (as essentially that's how the weight loss happens), it happened as a natural process of becoming full prior to going to sleep and having a shorter time frame to get the calories in.
My weight began to drop a bit too rapidly, so after the first week I began to track my calorie intake and ensure that I was at least hitting the 2,900kcal - 3,200kcal mark. So far, as of writing this article my weight has stabilised at 104.5kg, with no decrease in strength - which is pretty cool.
I'm no stranger to Intermittent Fasting. I first did it many years ago when I was full on carnivore, and I decided to try The Warrior Diet. This time around was the first time I had done IF on a plant based diet, this means zero animal products, and to be honest this time was a lot more nutrient dense, so I'm guessing that's partially why my energy levels were not as depleted
I did make adjustments to optimise my training though. Strength sessions were either the first part of the day, or in the afternoon, just prior to breaking my fast, and I kept all MetCon or HIIT training in the afternoon (so I could break my fast just after and optimise nutrient uptake).
I'm pleased with results so far, both physically and mentally, and intend to continue with this experiment for three months, providing no negative effects occur.
What the research says
According to a systematic review of over forty studies, IF is effective for weight loss, with a typical drop in 7 - 11lbs over ten weeks. The size of participants groups in the studies varied, as too did the IF protocol that was used.
While drop out rates were 0 - 65%, when compared to calorie restriction group there was no significant difference. So it's worth considering the IF protocol you use and making sure it's sustainable for you.
A randomised control trial (RCT) that followed 100 obese participants for one year did not find any significant weight loss to those that were on a calorie restriction diet.
In this trail, for the first 6 months, groups were divided into alternating days of fasting at 25% of calorie intake then 125% of of baseline calories split over 3 meals.
The other groups was set a calorie restriction of 75% split over 3 meals. Then at 6 months, a maintenance phase was introduced, with calories increased by 25% in both groups.
There was no significance in differences achieved in weight loss or body composition. Nor was their significant differences in fasting blood glucose, fasting insulin, or blood pressure.
But what the study did find however, was that there was a 38% drop out rate in the fasting group versus 29% in the calorie restriction group.
Pitfalls of IF
While there are numerous benefits from IF, Harvard Education suggests that it is not appropriate for everyone, as it can cause complications for
those with certain medical conditions or disordered eating.
So who is it not appropriate for?
IF in a Nutshell...
Ultimately the benefits of weight loss achieved through IF are the results of a calorie deficit, which can have subsequent metabolic, and hormonal benefits. IF hasn't been shown to be that much more significant or effective than simple calorie restriction over time.
That said, IF is a great way for some people to structure their nutrition and achieve similar results as standard calorie restriction, with bonus affects not necessarily captured in the research (which I have outlined in my experience).
I for one will be continuing with IF as and when it suits me. When it stops working for me, I'll no longer do it - and that's the important lesson, whatever you do, you have to make sure that is is sustainable and safe for you.