Intermittent fasting (IF) ― a way of eating that includes set periods of eating and not eating ― has long been studied in rats and other animals with positive results on health-related biomarkers and longevity. Recently this idea has caught on as a possible weight and health management tactic in humans. If you’re thinking about trying intermittent fasting, here’s what you’ll want to know.
What is Intermittent Fasting (IF)?
On this diet, you systematically select blocks of time in which you eat very little or nothing and and blocks when you eat normally. There are a number of different methods for pacing the periods of eating and fasting, some more challenging than others. The most popular is the 16:8 method where you fast for 16 hours per day and eat whatever you want during the other 8 hours of the day. For many, that means skipping breakfast and only eating between the hours of 12-8 p.m., but the hours are flexible based on what works best for you and your schedule. Other methods include fasting every other day for 24 hours or the 5:2 method, meaning 5 days per week you eat normally and 2 days you eat 25 percent of your calorie needs.
What can I eat?
All foods are on the table. Instead of restricting specific foods, IF emphasizes when or how much you should eat. However, it’s always recommended to eat a balanced diet when on IF and emphasize whole foods so that you get all of the nutrients you need to thrive.
What’s off limits?
No one food is off limits as long as you follow the guidelines of when you should eat.
Is there anything else to consider?
When deciding whether or not to try IF, you’ll want to consider how it affects your quality of life. Some people find the schedule of when to eat to be helpful in managing mindless snacking that may tend to happen in the evening. However, others find the limited hours to be a challenge either at work (when breakfast is skipped) or socially (if dinner is scheduled early). Mood swings, low energy, and irritability are a known side effect of IF, especially on the 5:2 or 24 hour plan due to little to no eating on certain days.
If you want to know the science…
The majority of the studies on intermittent fasting in humans have been conducted in controlled environments (i.e. all meals provided and supervised) and for short periods (weeks to a few months). So, we don’t know the long-term effects (positive or negative) of such a diet, or whether or not it’s really a sustainable way of living. While it may lead to health improvements and weight loss, intermittent fasting doesn’t appear to be any better than consistent calorie restriction, which has also been tied to living longer.
Disclaimer: The information in this article is not intended to be medical advice and if you are considering starting a new diet, work with your healthcare team to find the best approach for you.
Read about other popular diets in this series: