Why Intermittent Fasting Might Not Really Work, According To One Study

Intermittent fasting is currently a popular trend for people looking to lose weight. According to Monique Tello, MD, MPH, of Harvard Health, intermittent fasting is the concept of eating within a shorter window of time while eating nothing for the remainder of the day. The idea behind this dieting method is for the body to utilize its already stored fat to fuel itself instead of food. The science explains that fasting for longer periods allows insulin levels to fall, forcing the body to use that stored fat to keep active.

Dieters can customize their fasting plan to meet their schedule, but the general rule is to eat for just eight consecutive hours during the day and fast for the remaining 16 hours. Intermittent fasting can also involve one or two days a week where you don't eat at all, followed by five days of normal eating (also known as 5:2 fasting). Studies about the diet have been performed primarily on rodents, where data reveals the benefits of the trend. However, that doesn't guarantee that humans will have the same success.

Does intermittent fasting really work?

A 2022 study published by The New England Journal of Medicine looked at 139 human patients, half of whom dieted with a daily calorie limit and half of whom dieted with both limited calories and time-restricted eating (or intermittent fasting) over 12 months. The team examined changes in factors like body weight, BMI, and body fat among the two groups. Their conclusion suggested that for obese patients, time-restricted eating did not influence any of those factors more than the calorie restricting alone did; both groups had similar results in terms of weight loss. Though some human studies have shown beneficial results, other professionals find that intermittent fasting is concerning due to its restrictive qualities and effects on mood.

What does this contradicting information mean? Combined with the fact that most other studies about intermittent fasting have been done on animals, it suggests that we have more to learn about the diet before touting its benefits. According to Manpreet Mundi, MD, of Mayo Clinic, intermittent fasting may be more beneficial to people with "conditions associated with inflammation," such as arthritis. Meanwhile, those who are pregnant or breast-feeding may want avoid time-restricted eating. Dr. Mundi suggests consulting a doctor before beginning intermittent fasting, regardless of your medical condition. Whatever you decide, the CDC recommends a balanced diet containing fruits, vegetables, whole grains, seeds, nuts, eggs, beans, lean meat, protein, and low-fat or fat-free dairy.