What is intermittent fasting (and why you shouldn’t fall into the trap)?

Given the diet-obsessed world that we live in, I am sure that you’ve heard the term “intermittent fasting” thrown around in conversation once or twice. Besides knowing it’s the newest diet fad, how many of us really know what it is? If you ask me (disclaimer: anti-diet dietitian to-be here), intermittent fasting is just another way for you to deprive your body of food (under the guise of science and “health”). Anyhow… more technically speaking, intermittent fasting is a diet strategy that involves alternating between periods of eating and fasting. There are three main methods of intermittent fasting: time–restricted, modified and alternate day fasting. The time-restricted approach includes only eating during a certain period of the day, such as 16/8, where you eat within an 8 hour window and then fast for the remaining 16. The modified method, or 5:2 approach, involves eating regularly five days a week and then limiting yourself to a whopping 500 (!!) calories for the other two days. The last approach involves alternating fasting days (no eating) with non-fasting days (eating whatever you want). These fasting periods can last anywhere between 24 and 72 hours. 

This “trendy” diet is claimed to help you lose weight, burn fat, reduce risk of diabetes and lower blood pressure. The first claim can be applied to any diet nowadays… of course you can lose weight when you are depriving yourself of calories. Further, when you deplete your body of energy for 10+ hours, your body will start to use its fat stores for energy, which is where the glorified “fat loss” comes into play (and if it sounds too good to be true, it is). The thing is, unless you are a unicorn and a total outlier, the vast majority of people who lose weight by dieting (this includes IF), regain the weight they lost and often more within 5 years. The remaining purported benefits are limited to majority animal studies; therefore, further investigation in humans is needed, especially in long-term studies. The thing with rat studies is just that; they aren’t humans. Lab rats are confined to their cages, without the regular access to food, complex lifestyles and emotions that we humans have in our daily lives. Not only this, but when interpreting any diet intervention study, we must keep in mind the study duration (usually quite short), study participant dropouts, and the fact that a research study is carefully designed and not representative of the real world. While this emerging research touts some benefits, what is certain are the many downsides of intermittent fasting. Like any diet, these plans promise a lot, and under-deliver. They may “work”....until they don’t.

So, why should we steer clear of this newest trend? Without getting into the nitty gritty science, your body naturally fasts while you sleep, hence the word breakfast: breaking the fast. We can derive the benefits of fasting simply by going to bed, sleeping, waking up and having breakfast within an hour or so. Therefore, there is absolutely no need for voluntary fasting (i.e. self-imposed starvation) during the day to somehow better yourself and your health. 

The restrictive nature of this diet can also spiral into disordered eating. If you wait until your allotted “time” to eat, then you are more likely to overeat because you have been restricting yourself earlier in the day. This phenomenon is known as the restrict-binge cycle. When you deprive your body of food on certain days or during certain hours, your hunger can become urgent and often leads to eating large amounts of food, making you feel chaotic and out of control. After eating this food, you begin to fixate on it and then come the waves of guilt, the guilt that forces yourself into a period of restriction again. But because restriction isn’t sustainable, the toxic cycle starts all over again, only making you feel more uncomfortable, physically and mentally. During restriction periods, your body is so hungry that food is all you can think about; these food thoughts can become obsessive and all encompassing. While you are shaming yourself for that eating experience, your mind is simultaneously planning your next binge. Not only does this restriction-binge cycle mess with your head, but it also can lead to digestive issues and discomfort. As opposed to giving your body consistent nourishment and fuel throughout the day, your body is now trying to break down, digest and absorb nutrients all at once. The consequence of consuming such large amounts of food in a small window of time is constipation, diarrhea, bloating, and indigestion. So once again, it may “work”...until it doesn’t. Fasting may “work” in the sense that it can provide structure, lead to temporary weight loss due to energy insufficiency, and may provide a sense of increased energy (hello stress hormones), but for most humans, this can very quickly backfire and become self-sabotaging. 

Based on what you’ve read thus far, I’m sure you can assume that you’re not always going to be the best version of yourself when participating in this restrictive cycle. The side effects of intermittent fasting can (shockingly) be extreme, such as fatigue, headaches, weakness, irritability, hunger and low energy, which isn’t too far fetched considering you are quite literally robbing your body of energy. Being “hangry” is a real thing. And it's distracting constantly doing mental gymnastics with food. Beyond being hungry all of the time, and restricting calories can result in significant menstrual, fertility and reproductive issues in women. When your body does not get enough energy it first shuts down non-essential functions, such as our reproductive system, in order to conserve energy. Ignoring hunger cues and going long periods of waking hours not eating can also increase physiological and perceived stress, and while adrenaline and cortisol can keep us going somewhat, eventually our bodies will crash from insufficient nourishment from food. Due to the restrictive nature of this diet and increased likelihood of underfueling and elevated cortisol, intermittent fasting may result in the loss of a menstrual cycle. In order to maintain a healthy menstrual cycle, and therefore regular ovulation, women need to consume an adequate number of calories, which (unsurprisingly) cannot be achieved by diet culture’s newest culprit. While I am emphasizing folks with menstrual cycles right now, people of all genders can certainly be negatively impacted by IF (and any intentional pursuit of restricting energy intake). 

Moral of the story: you should eat when you’re hungry, and if that happens to be outside of your self-imposed window, then eat. No questions asked. You deserve to go out to spontaneous brunch or dinners with your friends and ENJOY the food regardless if it's in your “eating window” or not. You deserve to live a life where food does not dictate every move you make. You deserve to live a life of complete and utter food freedom!!

And a gentle, friendly reminder: coffee is not a meal!

References

Freire R. Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets. Nutrition. https://www.sciencedirect.com/science/article/pii/S0899900719301030. Published July 4, 2019. Accessed March 10, 2022. 

Intermittent fasting: What it is, types and how it works. Cleveland Clinic. https://health.clevelandclinic.org/intermittent-fasting-4-different-types-explained/. Published March 3, 2022. Accessed March 10, 2022.