This is one of the most talked about approaches to eating nowadays. It has been widely practiced for millennia across all races and religious beliefs. In the Eastern Hemisphere, fasting has been used for decades to help treat numerous degenerative diseases like rheumatoid arthritis, high blood pressure, type 2 diabetes, and high cholesterol. In the last decade the Western World has slowly been catching up with more scientific research on this intriguing topic helping to create new patterns of fasting to help modernize this ancient practice for everyone. So what exactly is Intermittent Fasting, and more importantly will it work for you?
Intermittent Fasting, or IF, is defined as a pattern of consumption that involves no eating for an extended period of time, then a period of normal eating. It's that simple! Now the complexity of IF comes in how you approach it. For simplicity I'm going to discuss the two main types and the most commonly used techniques in each.
There are two main types of IF, Alternate Day Fasting (ADF), and Time Restrictive Fasting (TRF). The first type, ADF, is a pattern of eating involving a 24 hour fast, followed by a normal day of eating. Some types of ADF involve easier fasting days, allowing for minimal calories on those days. The most popular types of ADF are the 5:2 Diet and the "Every Other Day Diet". The "Every Other Day Diet" was popularized by a book written by Krista Varady. This diet allows 25% of your normal calories on your fast day, then no restrictions of eating on your free day. The 5:2 diet consists of fasting two days a week followed by five days of non restricted eating. Now both of these diets are liberal approaches to IF and are much easier to stick with, but they also could encourage binge eating among certain populations. Therefore, if you're someone who can't easily control food cravings then these types might not work for you. When following ADF, I always recommend normal eating on your non fasting days. If you want to have a couple cheat days a month, then that should be fine.
ADF, in my personal experience, is a temporary pattern of eating. It's an easier approach to fasting for beginners but can be harder to maintain longterm for most people due to its extreme caloric restriction on your fast days. TRF, on the other hand, can be a solution to those who struggle with maintaining a fasting lifestyle.
The second major type, Time Restricted Fasting (TRF), is a pattern of eating within a a certain number of hours per day. The most common practice is fasting for 16 hours, then eating within an 8 hour time frame. This was popularized by the book, "The 8-Hour Diet" by David Zinczenko. This diet has no restrictions on the foods you eat during the 8 hour window of consumption, but does emphasize controlling your food portions. My personal experience is that with this diet you can still over-consume on a daily basis. So I would recommend keeping a food journal to make sure you’re still limiting your calories (if your goal is weight loss) and also make sure to consume healthy foods, not sugary refined ones. Now there are wide ranges of TRF out there today. Some are more strict, such as eating within a 1 hour window per day, or some have a more relaxed pattern, like eating within a 12 hour window per day. If you’re a beginner, I always recommend starting with a 12 hour window fast first, then increase you fast by 1 hour per week until you get to the 16 hour a day fast goal.
The benefits of IF are still being studied, but preliminary data suggest that it can help reduce the risk of cancer, improve immune function, increase energy, reduce inflammation, increase human growth hormone production, and increase your basal metabolic rate! It can also help with degenerative diseases, like Alzheimer’s , dementia, heart disease, type 2 diabetes, and rheumatoid arthritis. With new studies being conducted everyday, I'm sure we'll see more positive research being published in the near future.
Now, will Intermittent Fasting work for you? I personally believe everyone can benefit from some type of intermittent fasting in their life, but it's up to you to determine what type of IF works for your lifestyle. So, experiment with all the different types of IF out there and see what works best for you.
Before you start fasting, always consult your physician before making any major changes to your diet. Intermittent Fasting is not recommended for children, the elderly, and underweight people.