Currently, intermittent fasting (IF) is one of the most popular wellness trends. People everywhere are praising the new way of eating to help them lose weight and improve overall health and energy.
Many studies show the benefits of intermittent fasting may have on your body, brain, and lifespan. But what exactly is intermittent fasting, and how does intermittent fasting work?
Today, we’re going to answer all of your questions and concerns so that you can decide if IF is right for you. This is your ultimate guide to intermittent fasting.
What is Intermittent Fasting?
Intermittent fasting is an eating pattern of periods of eating and periods of fasting. Contrary to popular belief, it is not a diet per se. Meaning, it does not specify what you can and can not eat but rather when you eat.
IF, as a weight loss approach, has been around for a long time, in various forms but was first popularized in 2012 by Dr. Michael Mosley.
Intermittent Fasting Methods
There are several different ways of intermittent fasting, some with more extended periods of fasting. During fasting periods, you can drink non-caloric drinks like water, coffee, and tea. Do not add any milk, cream, or sugar. If you drink coffee or caffeinated tea during your fasting period, always supplement with extra water as caffeine will dehydrate you.
16/8: the most popular intermittent fasting method, also known as the Leangains protocol, restricts your daily eating to 8 hours and fasting for 16 hours. Usually, following the 16/8 method means you skip breakfast and have your first meal after 1 pm and your last meal before 9 pm. If you love breakfast, you can try the 9 am to 5 pm window to avoid late-night snacking. This is considered the easiest, most sustainable method.
5:2: in the 5:2 diet, you consume 500-600 calories two days a week–non-consecutive. On the other 5 days of the week, you eat normally.
Eat-Stop-Eat: For this method, you fast for 24 hours once or twice a week. This could be stopping eating at 7 pm on a Tuesday and then not eating until 7 pm on Wednesday. Fasting for up to 24 hours can result in a metabolic shift that allows your body to use fat as energy rather than glucose (1)
Benefits of Intermittent Fasting
The majority of those who intermittent fast are looking to lose weight. By reducing calorie intake, all of the above methods can result in weight loss as long as you don’t binge and consume insane amounts of ultra-processed foods.
A 2014 study showed that intermittent fasting could support 3-8% weight loss over a 3-24 week period. That same study found that people who intermittent fasted lost 4-7% of their waist circumference, meaning that stubborn belly fat that builds up around your waist and organs that causes disease was reduced significantly (1).
During the fasting period, we see human growth hormone (HGH) levels increase as much as 5-old. This can help foster fat loss and muscle gain. A change in hormones can also increase your metabolic rate from 3-14% allowing your body to process calories more adequately (2).
When fasting, a couple things happen on the cellular and molecular level. When fasting, your cells promote cellular repair processes like autophagy. This is when cells digest and eliminate old waste that builds up inside the cells (3, 4).
Lowers Insulin Resistance
Research has found that intermittent fasting can lower insulin resistance and lower blood sugar by 3-6% and fasting insulin levels by 20-31% — which can be extremely beneficial for type-2 diabetes (5).
A study done by University of Alabama took a small group of obese men with prediabetes and put half of them on a form of intermittent fasting called “early time-restricted feeding”, where they ate only between 7 am to 3 pm (8 hour window). The other group had a larger window of eating 7 am to 7 pm or 12 hours.
At the end of the five weeks, both groups maintained their weight (no lose, no gain). The group that ate within a 8 hour window, though, had significantly lower insulin levels and improved insulin sensitivity in addition to dramatically lower blood pressure (6).
Intermittent fasting may promote new nerve cell growth. It also increases BDNF, an important brain hormone. Most importantly, studies suggest that intermittent fasting may help protect against Alzheimer’s disease (7, 8, 9).
Who is intermittent fasting for?
Intermittent fasting may be a good idea for anyone looking to lose weight, improve brain function, and support overall wellness.
While both women and men praise the health benefits of intermittent fasting, a study showed that while it improves insulin sensitivity in men, it worsened blood sugar control in women (10).
There are also multiple reports of women who lost their period when on IF and went back to normal when they started eating the way they previously did. If women are still interested in trying intermittent fasting, its recommended to ease into the practice and if any issues come up (like a missed period) then to immediately discontinue intermittent fasting.
Some research also found that intermittent fasting made female rats emaciated, masculinized, and infertile. Though there are no human studies on this topic, those who are having infertility issues or are trying to conceive should consider waiting to try intermittent fasting. The same goes for women who are pregnant, breastfeed, or anyone who has a history of eating disorders (11).
How to Get Started Intermittent Fasting
Many people note that the 16/8 method is the easiest and most sustainable way to begin intermittent fasting. Try easing into this practice and see how your body feels. Then, if you feel so inclined consider moving onto the other methods of intermittent fasting and experiment with which best suits you and your needs.
The key here is to remember when you are in your eating window, to nourish your body with whole foods, lots of fruits and vegetables, and to avoid processed foods and binging.