Intermittent fasting, including food deprivation for 16 consecutive hours, is regularly recommended for weight loss. On the TikTok social network, the hashtag #jeuneintermttent has more than 92 million views.
The book “How to Fast” states that fasting releases natural healing forces in addition to being a treatment and anti-aging. Dr. Èvelyne Bourdua-Roy, co-author of the book and family physician certified in obesity medicine, answered our questions.
How to start intermittent fasting? Is it effective for losing weight? What are the effects on the body? Depriving your body of food for a period of time is becoming more democratic on social networks. Some apply it as part of a “detox cure”, others to lose weight or even as a spiritual experience.
According to Dr. Èvelyne Bourdua-Roy, co-author of “How to fast”, published by Thierry Souccar, fasting allows good metabolic health.
From Montreal, the founder of Clinique Reversa, a non-profit clinic for the reversal of chronic disease related to lifestyle based on low carb diet and fasting, answered questions from ETX Studio.
Are there different forms of intermittent fasting?
You have to start by distinguishing fasting” including intermittent fasting from a restricted eating window. Most people who talk about intermittent fasting are talking about skipping breakfast and eating two meals within a window of about 8 hours or less.
For example, we eat at 2 p.m. and have dinner at 8 p.m. We don’t eat anything until 2 p.m. the next day. The eating window is between 2 p.m. and 8 p.m., and the no-feeding or fasting window is between 8 p.m. (after the last bite of dinner) and 2 p.m. the next day. This is called the “restricted eating window” or TRE (Time Restricted Eating), but people often refer to it as “intermittent fasting”.
This is different from true fasting which is a hormonal metabolic state in which blood sugar levels are low, blood insulin levels are low, and the liver’s stores of sugar (glycogen) are empty or nearly empty. At this time, the body performs a kind of seesaw and various changes in the “mechanics” take place. The timing of this switchover varies from individual to individual, but on average it is about 18 to 36 hours.
Whether we’re talking about a restricted eating window (which many people call intermittent fasting) or actually talking about a physiological state of fasting, there can be some interesting benefits for metabolic health. For example, fasting lowers blood sugar (blood sugar) and insulin (blood insulin). When practiced regularly, it can help reverse insulin resistance and all the chronic diseases that come with it, like type 2 diabetes and idiopathic high blood pressure.
How many hours a day should you fast in a day to experience the benefits of intermittent fasting?
To know how many hours one should fast per day or per week, one must first have an idea of one’s insulin resistance or current metabolic health, determine one’s goals, and establish what one is capable of and interested in doing. You also have to take into consideration your body mass index (people with very low body fat should fast for less time and less often than people with an index above normal, for example), the drugs that the you are taking (there are contraindications or medications that will require close monitoring and possible adjustments) and your current overall state of health (it is not recommended to fast during pneumonia on antibiotics, for example ).
There is no universal recipe, and that’s what’s great. Finding your own fasting pattern and practicing it on a regular basis allows you to obtain the benefits of fasting and maintain them over time.
Is intermittent fasting effective for weight loss?
It can be, but it depends on the people. We see great inter-individual variability in our patients and participants. There are several reasons why fasting can help with weight loss: the metabolic shift that promotes a physiological state of catabolism and lipolysis (burning of body fat stores), the rebalancing of hunger and satiety hormones after fasting, improved insulin sensitivity (insulin is the master hormone of fat storage, so the more you secrete it because you are resistant, the easier it is to store fat fats and difficulty burning them), reduced calorie intake, etc.
Fasting, unlike low-calorie diets, does not lower basal metabolic rate. It even makes it slightly increase during the duration of the fast. By the way, we explore several misconceptions or myths about fasting in “How to Fast”, along with the relevant science.
However, if fasting is practiced by a person who has an eating disorder or food addiction and they lose control of their diet after the end of their fast, it will not be effective in losing weight and will be harmful to the mental health of that person. Fasting is then not indicated or at least not if it is of long duration.