Intermittent fasting

Intermittent fasting (IF) is a method of time-restricted eating which is most commonly seen in the fitness industry in the form of a 16-hour fast and an 8-hour eating window. Most commonly, the eating window begins around noon which practically means that you just skip breakfast.

Initially, this might seem completely counterintuitive because we are taught that breakfast is the most important meal of the day, we are taught to eat many smaller meals throughout the day and that this is the only “healthy option”. The scientific literature has shown this to be very far from the truth. Studies have been done on alternating days of fasting meaning that people ate one day and then fasted the entirety of the next day. Imagine having no calorie intake every other day, yet studies show no negative effects on health. However, there are some impractical facets of IF such as the adjustment period and combating hunger which can be a huge issue if you have a job or even worse if you work out multiple times a week after work. Obviously, alternate day fasting is only one of many varieties, most of which are less extreme. I mentioned one option in the introduction, there’s also a 15-hour fast with a 9-hour eating window and 14/10. On the other end of the spectrum, we have the warrior diet whereby you have a 20-hour fast and a 4-hour eating window or the most extreme variant called OMAD (one meal a day) which obviously entails eating only once a day. Before giving our final verdict on IF, let us look at the unique benefits it provides:

All of the aforementioned variations of IF are fantastic tools to help you deal with insulin resistance. However, insulin is not the only hormone receiving beneficial treatment from IF, growth hormone and glucagon also work better. Glucagon is responsible for mobilizing fat and converting it into energy. Just to avoid any confusion, that doesn’t mean that you will magically lose fat, because the main cause of weight loss is a calorie deficit. IF and improved glucagon secretion can help people who have already damaged their body with bad eating habits or with extreme diets. Some people talk about incredible improvements to their cognitive ability, but that seems to be a case-specific thing, there’s no scientific consensus on this. Some people benefit from time-restricted eating in terms of managing their caloric intake because they simply don’t have the time nor the appetite to overeat which in turn helps them stick to their diet.

All of this sounds peachy, but there are some arguments against IF. Some people fear that hunger will be insurmountable and for some it really is, but most commonly that is not the case because hunger doesn’t function in a linear fashion. In other words, hunger does NOT increase the longer you stay without food because the hunger hormone ghrelin which makes you hungry comes and goes like waves. The adjustment period lasts anywhere between 4 and 10 days on average. This causes the secretion of ghrelin to synchronize with your new meal pattern. The second argument usually comes from gym-goers who fear the infamous catabolic stat. They fear that they will lose all of their hard-earned muscle. Again, this couldn’t be further from the truth, your muscle mass is usually safe up to 40 hours and fasting on IF usually tends to last less than 24 hours. The third, also unfounded, complaint is that your metabolic rate will slow down and this is wrong on every level imaginable. A slightly more advanced version of this (also wrong), is that the thermic effect of food (calories required to process the food you eat) decreases due to a lowered meal frequency. This is wrong because the thermic effect of food operates on a total calorie basis rather than meal number.

A solid argument against IF is that in practice people often tend to jump on the bandwagon and think that IF is magical and in doing so they forget the importance of the caloric intake. They start overeating on calorie-dense food thinking that IF will fix everything. Another good argument against IF is that some people cannot overcome the adjustment period and they simply quit. The last argument is tied to protein absorption and its uptake in muscle tissue which is only pertinent to those hitting the gym hard. It’s generally better to spread your protein intake into several medium-sized portions of protein rather than two huge portions which is the case with people practising IF.  

Lastly, I’d like to leave you with a several practical takeaways:

• If is not superior to conventional methods of dieting, it has its advantages and disadvantages

• If can be combined with other diets, usually it’s combined with the ever-so-popular keto diet

• Don’t expect fast and magical results

• If you want to try IF start with a wider eating window, for example, 14/10 then work your way towards a narrow window like 18/6

• For most people the process of adapting can be difficult so if you want to try IF be aware of the fact that the first couple of days might not be easy

• IF is a great tool to help you combat insulin resistance

• IF is an excellent tool for people who have a big appetite and can’t be satisfied by many smaller meals

• IF can be a good choice if you find it hard to measure all your food because you’ll end up in a calorie deficit anyway since you don’t have less time to overeat

• Try to keep your windows and meal pattern consistent, if you start eating at 1 p.m. and your eating window ends at 9 p.m. then do it that way every day

• The point above doesn’t mean that you should stress over every second nor does it mean that you should be overly excited about the beginning of your eating window. IF is designed to help you get your mind off of food

• During the time you’re awake and fasting focus on something other than food, like your job or something productive in order to make the most out of the potential benefit of improved cognitive ability that some people experience

• Don’t be too restrictive whilst practising IF because the idea is not to waste all of your willpower and energy on resisting hunger AND on resisting cravings

• Don’t forget that the best diet is the diet you can stick to

• Don’t forget the lessons from my earlier post on eating healthy