Super Mega High Quality Data on Intermittent Fasting?

We found plenty of buzz words in this press release: mega-analysis, intermittent fasting, high-quality evidence. Who knew that “mega-analysis” was even a real thing? Well it is, but the use of it here to describe an umbrella review of meta-analyses deviates from the most common usage. Nonetheless, it sounds impressive. Setting all that buzz aside, JAMA Open Networks has a new review of the evidence for intermittent fasting and its quality available up to the beginning of this year.

The bottom line is quite simple. Intermittent fasting can work in the short term to help persons with overweight or obesity lose some weight.

An Umbrella Review of Meta-Analyses

Chanthawat Patikorn and colleagues have put together a very credible review of 11 meta-analyses of randomized clinical trials. They looked at 104 different different clinical outcomes with intermittent fasting and found six for which moderate to high quality evidence supported a benefit. These outcomes are all about body weight, composition, and cardiometabolic risk factors. Mostly they are relevant to persons with overweight and obesity.

What is important with this paper is that the authors have carefully analyzed the quality of evidence from all of these meta-analyses. Because intermittent fasting has stimulated so much research, grading the quality of evidence is an important task for understanding how confident we can be about the potential benefits it offers.

However, though this umbrella review brings together a big body of research, that doesn’t really make it a “mega” analysis. In fact, the most common definition of a mega-analysis is one that combines raw data from multiple studies into a single, large data set. Some have described this as a “gold standard” for empirical research. It’s not very common because of practical challenges it presents.

Sometimes Helpful, but No Magic

Stepping back to view the big picture, we can simply say from this study that intermittent fasting can be helpful. It clearly helps some people lose weight in the short term. Thus, it may also help with cardiometabolic risk factors. There’s no magic and no evidence it is intrinsically superior to other techniques for losing weight through dietary restriction. We still have much to learn about it.

For now, though, it’s merely an option that can work well for some, but not for others.

Click here for the study and here for the press release. For further perspective, click here and here.

Above Lake Superior, painting by Lawren Harris / WikiArt

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December 20, 2021