What is Intermittent Fasting all About?
By Julia Liber, Registered Dietitian
All of your friends are talking about Intermittent Fasting. You’ve seen it on Instagram and you’re genuinely curious about it. Maybe your family and friends have tried it out. You may be curious to see if this diet would work for you. Yet before jumping on the bandwagon, let’s cover some essentials.💡
What is Intermittent Fasting?🕐
Just as the name suggests, this diet is based on the principle of having set fed and fasting periods. To some extent, most humans fast intermittently by consuming food during the day and sleeping at night. What this diet does is offer a more regimented structure around your fed and fasting periods , by regulating which hours of the day are allocated to eating. Any hours outside of this period are considering fasting hours, in which no food can be consumed. There are different variations of this diet, including:
1️⃣The 16:8 method, where you consume food over an 8-hour period and fast for a 16-hour period.
2️⃣ The 5:2 method, where twice a week, you reduce your calorie intake to 25% of your needs.
3️⃣Alternate day fasting: every second day, you reduce your calorie intake to 25% of your needs.
4️⃣Eat Stop Diet: You fast for 24 hours once or twice a week.
A fast consists of consuming no foods. Fluids such as water, coffee and tea (without adding milk, cream, sugar or sweetener) are permitted. During the eating period, there are no restrictions on what can be consumed.
Reasons to try this diet
The main reason why people turn towards intermittent fasting is to lose weight.
How Does it Work?🤨
What Intermitting Fasting does is reduce the time period that you're eating, either in the course of a day or in the course of a week. It assumes that if you restrict the hours in a day(or the days in a week) in which you are allowed to consume food, you would consume less food than if you did not have fasting periods. This can work for some people, yet for others, fasting can cause extreme hunger, which can be uncomfortable. Furthermore, when entering a meal while being in a very hungry state, some people tend to overeat, leaving them feeling uncomfortably full afterwards. If entering a meal while being extremely hungry becomes a habit, this can lead to overeating on a regular basis, which in turn can cause weight gain. The attribution of fasting to extreme hunger has been demonstrated mostly for the alternate day fasting, yet a study on time restriction has shown that methods similar to the 16:8 method did not increase hunger and in fact decreases the desire to eat in the evening(Sutton et al.,2018).
Does it actually work❓
Research studies have examined the effect of intermittent fasting on weight loss and biological markers such as cholesterol, triglycerides(Tinsley et al.,2015) and fasting glucose(Patterson et al.,2017). The results of the studies have demonstrated that alternate-day fasting and whole-day fasting can reduce body weight and improve health markers, but it’s no more effective than calorie restriction. (Patterson et al; Tinsley et al.,2015). Furthermore, alternate-day fasting may not be feasible due to the side effect of extreme hunger associated with this regimen(Patterson et al., 2017).
Another study(Sutton et al.,2018) has shown that early time-restricted feeding, a variation of the 16:8 method, can improve health markers in men with prediabetes by lowering factors such as blood pressure and improving insulin sensitivity when keeping body weight stable. This study demonstrates that health markers can be improved in the absence of weight loss.
When not to go this route🙅♂️
This diet is not for children, nor pregnant and breastfeeding women, people with a history of eating disorders, people suffering from chronic disease(such as diabetes among others) as well as people on medications.
Before trying a new diet, always consult with your doctor or dietitian to find out if the diet is safe for you.
Should you try it out?
Overall, research has shown that there may be some benefits associated with this diet. Yet, current evidence suggests that it is no more effective in weight loss than the conventional caloric restriction method.
Furthermore, restriction, whether caloric, time-restricted eating, eliminating foods to name a few can have a negative impact on your relationship with food. It is possible to consume a healthy and balanced diet without following strict food rules. To find out more about my position on weight-loss diets, you can check out my previous article. The approach I take with my clients is focusing on developing healthy eating patterns while being mindful of factors that can affect your eating habits: including emotions, social factors and mindfulness.
We focus on nutrition for physical as well as for mental health. If this approach is something that speaks to you, you can book a call with me.
Davies et al., (2018, January 31). Intermittent Fasting. Vancouver Dietitians. https://www.vancouverdietitians.ca/post/2018/02/05/intermittent-fasting.
Dietetically Speaking. (2017, February 12). Intermittent Fasting Diets. Dietetically Speaking. https://dieteticallyspeaking.com/intermittent-fasting-diets/.
Gunnars(2020, January 1). 6 Popular Ways to Do Intermittent Fasting. Healthline. 6 Popular Ways to Do Intermittent Fasting.
Hall (2015, December 15). Intermittent Fasting. Science. https://sciencebasedmedicine.org/intermittent-fasting/.
Patterson et al., (2017). Metabolic Effects of Intermittent Fasting. Annual Review of Nutrition, 37(1), 371–393. https://doi.org/10.1146/annurev-nutr-071816-064634
Patterson et al., (2015). Intermittent Fasting and Human Metabolic Health. Journal of the Academy of Nutrition and Dietetics, 115(8), 1203–1212. https://doi.org/10.1016/j.jand.2015.02.018
Poinier et al ,. (2019, December 11). Healthy Eating: Recognizing Your Hunger Signals. HealthLink BC. https://www.healthlinkbc.ca/health-topics/zx3292.
Sutton et al., (2018). Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism, 27(6). https://doi.org/10.1016/j.cmet.2018.04.010
Tinsley et al., (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, 73(10), 661–674. https://doi.org/10.1093/nutrit/nuv041
The information presented in this article is intended for informational purposes only. They are not intended to treat, diagnose, or give specific medical advice. The information in this article is not intended as medical advice, medical nutrition therapy, or individualized nutrition. No content on this should ever be used as a substitute for direct medical or nutritional advice from your doctor or Registered Dietitian.