Intermittent Fasting (IF) has been on the rise as one of the hottest diets for weight loss and longevity, alongside ketogenic and paleo-style diets. Some of the most famous celebrities and comedians, including Joe Rogan, Chris Pratt, Jennifer Lopez and Beyoncé, swear by this style of eating as the main reason for their weight loss success. Proponents of IF boast that it is not what or how much you eat, but when you eat and how long you fast, that can promote weight loss, decrease fat mass, improve blood sugar levels and slow down the aging process. But, is there enough scientific evidence to support these too-good-to-be-true claims?
First, a little more on IF: IF is an eating pattern that cycles between a set time for fasting and a set time for eating within a 24-hour cycle. The idea is that this cycle will allow the body to achieve a fasted, or post-absorptive state, where fat stores are used as the primary energy source. How many hours do you need to fast in order to achieve the fat-burning fasted state? At minimum, 12 hours without any food. One of the most popular IF diet patterns calls for a little more. It is called the 16:8 cycle, where one is allowed to eat within an eight-hour window and then fasts for the next 16 hours.
According to a research study conducted by Dr. Satchin Panda, an award-winning genomics researcher, there is statistical significance in the use of IF on weight loss and other factors including improved blood sugar and cholesterol levels – in mice. A 2018 study looked at all of the most recent animal and human trials of IF and concluded that IF may in fact be beneficial on weight, body composition (the ratio of fat to muscle), heart health and aging. This article refuted, however, that the research done with humans is not robust enough for medical professionals to recommend IF as a weight management tool.
As optimistic as some of the new research may seem, IF raises some other questions such as how does this way of eating impact mood, mental focus and eating habits? And most importantly, is it safe? Time-restricted eating, as indicated in its name, is restrictive. For some, this can cause a pattern of disordered eating habits or accentuate a current eating disorder. IF is also not recommended for diabetics taking anti-diabetic medication that causes low blood sugar, as the risks for low blood sugar are increased during fasting. Additionally, low blood sugar levels can cause us to crave sweets and carbohydrate-dense foods, as our bodies send us the message to get blood sugar levels back to normal. This could result in overeating (during the allotted time of eating), counteracting any potential weight-loss benefits. Lastly, this diet can also negatively impact mood. When our blood sugar levels are low after a 16-hour fast, our brain can no longer function at full capacity. This can make us foggy, more easily irritated and much less energized, which could make it easier to skip your morning workout and be less productive at work.
Bottom line: Forcing oneself to eat within a small period of time rather than spreading out meals over the course of a day may be difficult, aggravating and lead to overeating, thus, not worth the “wait.” Additionally, if you’ve noticed, the celebrities who have sworn by IF have maintained healthy lifestyles for a majority of their careers, so it’s a bit ambitious to suggest that IF is the reason for their results. To make the most healthful decisions for you and your body, doing thoughtful research before making any dietary changes and paying attention to the way they make you feel is a must.
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Written by: Michelle Boucher, Wellness Workdays Dietetic Intern
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3. Nutrients