What is Intermittent Fasting?

Intermittent fasting is a method of eating (for either health or weight loss reasons) that restricts calorie consumption to a specified period of time. A common intermittent fasting diet is the 16:8 plan in which you consume your daily calories only in one 8 hour window per day and then fast for the remaining 16 hours. Some fasting plans require that you abstain from all food for one to two days per week while eating normally on the other days.

How Does Intermittent Fasting Work?

There is little contention on the fact that intermittent fasting works but how it works is still up for debate. Some studies point to the differences in how your body burns energy when you’re in a fasted state versus a non-fasting state: “During fasting, the body uses up glucose and glycogen, then turns to energy reserves stored in fat… in the form of chemicals called ketones. These chemicals help cells—especially brain cells—keep working at full capacity” (National Institute on Aging).

Other researchers have suggested that there are other reasons that intermittent fasting works: “Intermittent fasting regimens are hypothesized to influence metabolic regulation via effects on (a) circadian biology, (b) the gut microbiome, and (c) modifiable lifestyle behaviors, such as sleep” (Patterson & Sears, 2017). For example, if you’re only eating from the hours of 10 AM to 6 PM, that compulsion to go in the fridge for that late-night snack won’t be as strong.

Is Intermittent Fasting Safe?

There is very little debate on the safety of intermittent fasting diets simply because it has been studied extensively over a number of decades. Intermittent fasting may also have a variety of other health benefits, including extending your lifespan: “In many experiments, calorie-restricted feeding delayed the onset of age-related disorders and, in some studies, extended lifespan” (National Institute on Aging).

Other studies suggest that there are more potential benefits to intermittent fasting, especially for insulin-related health issues like diabetes: “An [intermittent fasting diet] may provide a significant metabolic benefit by improving glycemic control, insulin resistance, and adipokine concentration with a reduction of BMI in adults” (Cho et al., 2019).

It should be noted that more studies need to be conducted on human patients as many studies have been conducted on animals. Because researchers were able to almost perfectly control their animal subjects’ caloric intake, the data is considered accurate in most cases. However, in human studies, there is no guarantee that the human subjects actually adhered to either the fasting intervals or to the caloric restrictions, if there were any. There may be some interactions that are adverse for some people who try intermittent fasting so, as always, speak with your doctor before you start on any diet plan.

Types of Intermittent Fasting

There are a number of different intermittent fasting programs that you can implement to help you lose weight. It’s important to do your own research to find out which fasting plan is best for you and your life, your weight loss needs, and your health. Please note that there are other methods of intermittent fasting in addition to these but these tend to be the most popular.

• 16:8 Intermittent Fasting: The 16:8 intermittent fasting plan (sometimes called the 16:8 diet) states that you eat all of your daily calories in the 8-hour window while abstaining from anything with calories (water, black coffee, and plain tea are okay) for the remaining 16 hours in the day. For example, your window to consume food might be between the hours of 11 AM to 7 PM. This would allow you to consume lunch and dinner within the normal eating hours while skipping breakfast.
• 5:2 Eating: Another type of intermittent fasting is called 5:2 eating (also known as alternate day fasting). This means that you’ll eat normally for five days per week and then on two days, you restrict your caloric intake to around 500 calories per day. For example, you might eat normally on all days except for Mondays and Thursdays.
• Periodic Fasting: Periodic fasting is done sometimes for varying periods of time, hence the name. Some people like to fast for a weekend or for several days to jump-start their weight loss while others go on extended fasts. “The results from 1422 subjects showed for the first time that Buchinger periodic fasting lasting from 4 to 21 days is safe and well-tolerated. It led to enhancement of emotional and physical well-being and improvements in relevant cardiovascular and general risk factors, as well as subjective health complaints” (de Toledo, 2019).

Tips for Intermittent Fasting

For a lot of people, the thought of not eating for an extended period of time can be off-putting. Thankfully there are a number of tips to help suppress and/or control your hunger

• Drink More Water: Many times, when you think you’re hungry, you’re actually just thirsty. Whenever you think you’re getting the stomach grumbles, drink a large glass of water and then wait around half an hour to see if you’re still hungry.
• Enjoy Cinnamon Tea: Cinnamon has been shown to help reduce body weight, namely as an appetite suppressant (Mousavi et al, 2020). It should be noted that cinnamon also has antioxidant, anti-inflammatory, anti-microbial, and lipid-lowering effects (Kawatra & Rajagopalan, 2015). Here are the top-rated cinnamon teas from Amazon.
• Eat More Protein: Consuming more protein can help you feel fuller longer and deter you from snacking outside of your eating hours (Westerterp-Plantenga, Lemmens & Westerterp, 2012).

Pros of Intermittent Fasting

• No Calorie Counting – Unless You Want To: Numerous studies have proven that just limiting the hours in which you consume food on a daily basis can help you lose weight, even without counting calories (Gabel et al., 2018). Of course, you’re still welcome to count calories or combine intermittent fasting with another diet like the Atkins diet or the Mediterranean diet.
• Tons of Research: Intermittent fasting has been studied extensively for many decades, meaning that there are a ton of studies out there on the benefits and risks. (Note all of the citations in this article alone!) Thankfully, the vast majority of studies point to the vast number of potential health benefits and relatively few risks.
• Numerous Potential Health Benefits: Aside from weight loss, there are a number of other health benefits to intermittent fasting including “increased resistance against oxidative stress, decreased inflammation, and promoting longevity” (Stockman et al., 2018).

Cons of Intermittent Fasting

• Periods of No Food: For some people who enjoy eating and enjoying food, intermittent fasting may be tough to adhere to simply because there are periods of time where you can’t eat anything.
• Potential Temporary Weakness: Especially in the early days and weeks of intermittent fasting, you may feel sapped of energy for a time. Ideally, your body will adjust to the changes and this should only be a temporary drawback.
• More Studies Needed For Some Groups: More studies need to be conducted for certain subsets of the population, including premenopausal women, the elderly, those with type 2 diabetes, and normal-weight subjects (Harvie & Howell, 2017).

Books on Intermittent Fasting

• Delay, Don’t Deny: Living an Intermittent Fasting Lifestyle (Gin Stephens & Dr. Kenneth Power): “Tired of counting calories, eliminating foods from your diet, or obsessing about food all day? If so, an intermittent fasting lifestyle might be for you! In this book, you will learn the science behind intermittent fasting, and also understand how to adjust the various intermittent fasting plans to work for your unique lifestyle.”
• The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting (Dr. Jason Fung & Jimmy Moore): “Fasting is not about starving oneself. When done right, it’s an incredibly effective therapeutic approach that produces amazing results regardless of diet plan. In fact, Toronto-based nephrologist Dr. Jason Fung has used a variety of fasting protocols with more than 1,000 patients, with fantastic success. In The Complete Guide to Fasting, he has teamed up with international bestselling author and veteran health podcaster Jimmy Moore to explain what fasting is really about, why it’s so important, and how to fast in a way that improves health.”
• The Obesity Code: Unlocking the Secrets of Weight Loss (Dr. Jason Fung): “Everything you believe about how to lose weight is wrong. Weight gain and obesity are driven by hormones—in everyone—and only by understanding the effects of insulin and insulin resistance can we achieve lasting weight loss.”
  

Evidence-Based Studies on Intermittent Fasting

• 16:8 Intermittent Fasting and Weight Loss: “These findings suggest that 8-h time restricted feeding produces mild caloric restriction and weight loss, without calorie counting. It may also offer clinical benefits by reducing blood pressure” (Gabel et al., 2018).
• Intermittent Fasting and Weight Loss: “All studies reported significant weight loss for [intermittent energy restriction] groups. Average weight loss was approximately [0.44-1.7 lbs.] per week” (Davis et al., 2015).
• Numerous Health Benefits: “At the cellular level, IF may also increase resistance against oxidative stress, decrease inflammation, and promote longevity” (Stockman et al., 2018).
• Intermittent Fasting and Cardiovascular Health Benefits: “The IF diet limits many risk factors for the development of cardiovascular diseases and therefore the occurrence of these diseases” (Malinowski et al., 2019).
• Intermittent Fasting on the Lipid Profile: “Normocaloric and hypocaloric intermittent fasting may be a dietary method to aid in the improvement of the lipid profile in healthy, obese and dyslipidemic men and women by reducing total cholesterol, LDL, triglycerides and increasing HDL levels” (Santos & Macedo, 2018).