For as long as we can remember, people have been swooning over the magic of intermittent fasting. The hype told us it was a natural way to eat whatever we want and lose weight. That hype even suggested it could help us live longer and prevent cancer!

Pish posh says the Cochrane Collaboration. The sum and substance of a new and very thorough review says there’s no magic in intermittent fasting. It’s just a diet. Luis Garegnani was the lead author of this review. He explains the implications:

“Intermittent fasting just doesn’t seem to work for adults with overweight and obesity trying to lose weight. It may be a reasonable option for some people, but the current evidence doesn’t justify the enthusiasm we see on social media.”

Methods and Findings

Garegnani and colleagues examined whether intermittent fasting helps adults with overweight or obesity lose weight and improve health outcomes, compared with traditional dietary advice (calorie restriction or eating healthier) or no advice. They also looked for evidence for effects on quality of life, unwanted side effects, and other health measures like diabetes markers.

To do this, they systematically searched major health research databases for randomized trials up to November 2024. They included 22 clinical trials involving 1,995 adults with overweight or obesity, conducted in various regions around the world. Participants in these studies received random assignments to follow intermittent fasting, traditional “regular” dieting advice, or no treatment (e.g., assignment to a waiting list).

The numbers told them intermittent fasting probably doesn’t lead to more weight loss than traditional dieting advice. The difference in weight loss between these approaches was very small or negligible. Compared with doing nothing, intermittent fasting also likely doesn’t improve weight loss.

They also found little to no difference in quality of life when intermittent fasting was compared with traditional diets or no treatment. The evidence was inadequate for drawing conclusions about unwanted effects or long term outcomes.

Probably Not the Last Word

It is, however, safe to say that this will not be the last word on intermittent fasting. Too many researchers and people living with obesity have found that it can have value in their experience. For instance, Adam Collins at the University of Surrey says:

“This robust review and meta-analysis of intermittent fasting (IF) focuses specifically on weight loss and quality-of-life benefits. The headline finding that intermittent fasting is no better (or worse) than standard dietary advice or doing nothing is attention-grabbing, but should, I feel, be interpreted with a little caution.

“Whilst this review is of interest and will generate clicks, it should not distract from the consensus from other studies in the scientific literature that IF regimens are an effective tool for weight loss.”

Once again, for weight management one size does not fit all. And neither can a single study sum up the value of a tool for dealing with it.

Click here for the study, here, here, and here for further perspective.

The Church Scene in Much Ado About Nothing, painting by Alfred W. Elmore / Wikimedia Commons