Study finds intermittent fasting doesn't actually increase weight loss

  • A clinical trial found that intermittent fasting didn't help much with weight loss.
  • It achieved largely the same results as traditional eating plans.
  • It posed the risk of losing lean body mass, instead of fat mass.

Intermittent fasting – not eating for certain regular intervals in order to lose weight – has become increasingly popular over the last few years. 

The idea is that it helps you expend more energy and burn more calories than you consume, without putting in too much effort.

While not advised for everyone, earlier studies have found that it has some health benefits, such as improving heart conditions, lowering cholesterol and increasing focus. 

But new research is now refuting these claims and stating that you won't lose much more weight compared to the weight you'll lose when sticking to a three-meals-a-day diet.

READ | Study recommends combo of Mediterranean diet and intermittent fasting for the heart 

Study participants

Published in JAMA Internal Medicine, the small randomised clinical trial included 116 overweight and obese men and women between the ages of 18 and 64.

They were split into two groups – the control cohort eating a normally structured three meals a day, and those on a time-constrained diet. The latter could eat what they needed between 12:00 and 20:00, but fasted for the rest of the time and were only allowed noncaloric drinks.

The researchers believed skipping breakfast was easier than skipping dinner and did not provide any guidance on calorie intake.

Besides measuring their weight, they measured fat and lean mass; insulin levels; glucose; blood sugar; and energy intake and expenditure during and outside fasting times. 

READ MORE |5 reasons why intermittent fasting may not be right for you


While there was a decrease in the weight of 1.17% in the intermittent fasting group, there wasn't a significant difference compared to the control group that lost 0.75% of their total weight. Most of the loss was also lean mass and not fat mass, which serves as a reminder not to neglect protein intake while fasting intermittently.

They also found no significant difference between the groups when it came to the measured metabolic markers.

The researchers believe easy and straightforward weight loss measures and adherence to lifestyle changes are necessary for health benefits. While intermittent fasting seemed like a good fit, the results indicated otherwise.

"The [time-restricted eating plan] seems attractive as a weight-loss option in that it does not require tedious and time-consuming methods, such as calorie-counting or adherence to complicated diets," write the authors.

"Indeed, we found that self-reported adherence to the [time-restricted eating] schedule was high. However, in contrast to our hypothesis, there was no greater weight loss with [time-restricted eating] compared with the [consistent meal timing]."

READ | 10 Health benefits of intermittent fasting diets

Image credit: Getty Images

We live in a world where facts and fiction get blurred
In times of uncertainty you need journalism you can trust. For 14 free days, you can have access to a world of in-depth analyses, investigative journalism, top opinions and a range of features. Journalism strengthens democracy. Invest in the future today. Thereafter you will be billed R75 per month. You can cancel anytime and if you cancel within 14 days you won't be billed. 
Subscribe to News24
Voting Booth
Have you entered our Health of the Nation survey?
Please select an option Oops! Something went wrong, please try again later.
27% - 9950 votes
73% - 26266 votes