Intermittent fasting isn’t more effective than calorie-counting - study

A comprehensive study which lasted an entire year found that there’s no difference between this popular trend and simply limiting caloric intake. What’s the truth?

 Intermittent fasting (illustrative) (photo credit: Wikimedia Commons)
Intermittent fasting (illustrative)
(photo credit: Wikimedia Commons)

Intermittent fasting, known as 16:8, (eat within eight hours, then fast for 16)  has recently been quite trendy, but now it’s receiving serious blowback. Researchers in China found that this method used by celebrities like Beyonce or Jennifer Aniston has no significant advantages over reducing calories in trying to lose weight.

"Our data suggest that calorie restriction is the deciding beneficial factor of a time-limited eating regime," said researchers from Southern Medical University in Guangzhou, China in their research.

"Bottom line, the main cause of weight loss, as well as a reduction in body fat, abdominal fat, blood pressure and glucose and fat levels, depends on reducing calorie intake, regardless of the distribution of food and beverages consumed throughout the day," said Alice Lichtenstein, senior scientist at the Cardiac Nutrition Laboratory, Tufts University to CNN.

The principle of all diets is similar and aims to create an equation in which fewer calories are put into the body than the body burns. Intermittent fasting achieves this goal by limiting the number of calories on certain days of the week or at set times during the day. Intermittent fasting also helps in reducing appetite by slowing down metabolism.

The study, published last weekend in the New England Journal of Medicine, divided 139 people who were either significantly or moderately overweight into two study groups that were followed up for a year.

 A flexitarian diet involves eating more plant-based meals (credit: UNSPLASH) A flexitarian diet involves eating more plant-based meals (credit: UNSPLASH)

One group limited daily food intake to 1500-1800 calories a day for men, and 1200 to 1500 calories a day for women. Men and women in the second group were told to eat these amounts of calories, but to eat only between the hours of 8:00 and 16:00. To check how consistent participants were, they kept daily food diaries and photographed all the food they ate.

At the end of the year, the two groups lost between 6.4 to 8.2 pounds on average, but eating on a time-limited schedule didn’t make a significant difference in weight loss between the two groups.

There was also no real difference in other markers of weight loss such as BMI (body mass index, a popular yet less accurate way of measuring weight), waist circumference, body fat or metabolic risk factors such as insulin resistance and blood pressure.

This isn’t the first time that scientists have disproved the effectiveness of intermittent fasting, and a study published in JAMA Internal Medicine in 2017 showed that intermittent fasting didn’t cause more significant weight loss than a regular diet that includes a reduction in daily calories. Also, the dropout rate from it was high at 38%. This figure is problematic as the main goal of changing dietary habits is to create sustainable eating habits which support long-term weight loss.

Indeed, the results of a year-long clinical trial haven’t surprised many researchers who’ve argued for years that limiting time instead of calories isn’t the magic formula for weight loss. Eating a balanced and healthy diet, especially with nourishing and satisfying plant foods combined with animal proteins and exercise is the safest, most effective way to lose weight.