Intermittent fasting — the trendy dieting technique favored by celebs like Jennifer Aniston, Kourtney Kardashian and Gwyneth Paltrow — may actually be unhealthy.
That’s what a recent study revealed after examining the effects of the popular diet, in which people restrict their eating to a limited window of time during the day.
The research, published in the International Journal of Epidemiology, tracked the eating habits of more than 103,300 adults (79% of whom were women) for an average of seven years.
There were 963 new cases of Type 2 diabetes among the participants during the study. And people who regularly ate breakfast after 9 a.m. had a 59% higher rate of Type 2 diabetes than those who ate breakfast before 8 a.m.
“Biologically, this makes sense, as skipping breakfast is known to affect glucose and lipid control, as well as insulin levels,” Anna Palomar-Cros, lead author of the study, said in a news release.
“This is consistent with two meta-analyses that conclude that skipping breakfast increases the risk of Type 2 diabetes,” Palomar-Cros added.
Another behavior that seemed to increase the risk of Type 2 diabetes was regularly having a late dinner (after 10 p.m.). Conversely, eating more often during the day — about five times throughout the day — lowered the risk of the disease.
Prolonged fasting seemed to be beneficial only when it was done by having breakfast before 8 a.m. and having an early dinner.
“We know that meal timing plays a key role in regulating circadian rhythms and glucose and lipid control, but few studies have investigated the relationship between meal timing or fasting and Type 2 diabetes,” Palomar-Cros said.
This latest study adds to a growing body of evidence calling out the intermittent fasting craze as little more than a fad diet.
A 2022 study, published in the journal of the Academy of Nutrition and Dietetics, found that skipping breakfast was associated with a higher risk of dying from cardiovascular disease.
Other studies have found that intermittent fasting is about equal to counting calories when it comes to weight loss.
For example, a study published in the Annals of Internal Medicine found that people who participated in intermittent fasting and ate all of their calories within an eight-hour window lost the same amount of weight as those who ate whenever they wanted but counted calories.
Nonetheless, the intermittent fasting diet does have its fans, and some research supports its effectiveness.
A recent study among people with Type 2 diabetes found that those on a time-restricted eating diet lost 3.55% of their body weight over six months, while a calorie-restricted group lost none.
“Many people find counting calories very hard to stick to in the long term, but our study shows that watching the clock may offer a simple way to decrease calories and lose weight,” Vicky Pavlou, a doctoral student at the University of Illinois Chicago, said in a news release, as reported by US News.
“There are multiple types of medications for those with Type 2 diabetes, some of which can cause low blood sugar and some that need to be taken with food,” Pavlou added. “Therefore, it is important to work closely with a dietitian or doctor when implementing this dieting approach.”