Key Takeaways

  • Intermittent fasting can be used to lose weight, reduce insulin levels and inflammation and improve memory and cognition
  • There are many different methods of intermittent fasting, making it a highly flexible and personal lifestyle choice
  • Angela Fitch, MD, FACP, FOMA, associate director of the Massachusetts General Hospital Weight Center, shares tips for creating a healthy intermittent fasting plan

Intermittent fasting (IF) is a popular lifestyle choice for those trying to lose weight and live a healthier lifestyle. Fasting for 12-16 hours is thought to decrease insulin levels, inflammation and encourage weight loss.

According to Angela Fitch, MD, FACP, FOMA, the associate director of the Massachusetts General Hospital Weight Center, IF can be adjusted to fit your personal schedule and preferences. She outlines three popular methods of IF and tips to create a healthy IF plan.

What is IF?

IF is an eating pattern that separates periods of fasting and eating in your day. During the fasting periods you do not consume any calories, and only drink water, black coffee or tea. A 12-16 hour fasting period each day may cause beneficial metabolic changes, including weight loss, decreased insulin levels and cholesterol, and improved memory and cognition. IF primarily works by keeping insulin levels low throughout the day, which promotes the use of fat for energy instead of storage.

Different Versions of IF

Dr. Fitch presented on IF in a recent Facebook Live, and provided information on different versions of IF and ways to personalize it.

One of the greatest benefits of IF is its flexibility. There are many different versions of IF that allow you to customize the timing of your fasting periods. Some individuals prefer an earlier window for eating, which might work if you wake up early or find yourself hungriest in the mornings. Or, perhaps you work late hours or enjoy going out to dinner with friends in the evening. In that case, a later eating period might work best for you. IF can be highly personalized, and Dr. Fitch encourages individuals to adjust the timing to work best for them.

The Most Popular Versions of IF

Time-restricted Feeding
The classic form of IF, in which you consume your daily calories during an 8-12 hour block each day, and fast for the remaining 12-16 hours

  • This method can be adjusted to different periods in the day depending on personal preferences. For example, you can have an earlier eating period between 7 am and 5 pm, with a 14 hour fast for the remainder of the day. You could also choose a later window, eating between 12 pm and 8 pm, fasting for 16 hours. Any version of timing, so long as you are fasting between 12-16 hours, will provide the same benefits. It is also important that you do this every day for the most part. Doing this one day and not the other doesn’t help

The 5:2 Method
Eat normally for five days each week, and limit consumption to 500-600 calories for the remaining two days

  • This method might work for you if fasting every day is too difficult, or you prefer to get your fasting periods out of the way all at once. An example of this method could be eating normally during the workweek (Monday through Friday), and fasting on the weekends (while consuming 500-600 calories each day)

24-Hour Method
Consume no food for a full 24 hours, once to three times each week

  • Like the 5:2 method, this might work for you if you prefer to fast all at once and only commit to it a couple of times a week. This method differs from the 5:2 method in that during the fasting day you consume no calories at all, whereas 5:2 allows you to consume a small number of calories

In any of these versions, it is important to try to consume healthy, unprocessed foods, Dr. Fitch suggests. While there are no restrictions on what you can and cannot eat, keeping a healthy, balanced diet will enhance the benefits of IF.

Tips for Creating a Healthy IF Plan

  • Go slow: Start off with a 10 hour fast, which can be in the morning or evening. Play around with the time frame you choose to fast and find one that works best with your schedule and preferences. Try to increase the amount of time you fast by one hour each week, with the goal of eventually reaching a 14-16 hour fasting period
  • Make healthy choices: During the time that you are eating, make sure to get enough protein in your diet to avoid a deficiency. Additionally, try to get most of your carbohydrates from non-starchy vegetables, fruits, and nuts, to get enough fiber, vitamins, and minerals each day
  • Stay positive: Don’t feel guilty if at first you find IF challenging. IF is an adjustment if you are used to eating three meals spread out in the day. If you don’t stick to the fast one day, just try again the next

IF may not be for you if you have an eating disorder, are pregnant or breastfeeding, have diabetes, are taking certain medications or are under 18 years old. Consult with your physician if you have any of these conditions before trying IF.

Related article: How Intermittent Fasting Can Help You Live a Healthier Lifestyle