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With a growing number of trials exploring intermittent fasting in people it’s not clear what this mice study brings to the table


2 Star

On-and-off fasting helps fight obesity

Our Review Summary

This news release describes a study about intermittent fasting in mice, in which the mice that fasted weighed less four months later than the mice that did not fast. The finding described in the news release only applied to mice being fed a high fat diet (45 percent from fat), whereas when on normal chow and intermittent fasting on normal chow, there wasn’t much difference.

The release was short on numbers and descriptions of measurements used, and implied that the mouse studies could benefit people, without any caveats that such a transfer of mouse discovery to practical application in humans often fails.

The release did name the funders and avoided sensationalizing obesity.


Why This Matters

Obesity is an enormous public health problem. But this release misleads the reader into thinking its conclusions will transfer from the mice in the study to human patients with obesity.

We were disappointed by this quote from one of the researchers: “Intermittent fasting without a reduction in calorie intake can be a preventative and therapeutic approach against obesity and metabolic disorders,” says Kyoung-Han Kim.” Based on the published study, we don’t find any evidence that this has been proven for human patients.

A more accurate quote would be, “Intermittent fasting without a reduction in calorie intake can be a preventative and therapeutic approach against obesity and metabolic disorders in mice being fed a high fat diet.”


Does the news release adequately discuss the costs of the intervention?

Not Applicable

The release doesn’t discuss costs of the mice chow used in the study but we’ll still rate this Not Applicable since our emphasis is on human interventions. People wanting to embark on a semi-fasting program could do so without purchasing any products.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The benefits are given very sketchy treatment. For example, the release says, “Four months later the mice in the fasting group weighed less than those in the control group who continued to eat the same volume of food.”

The release never tells us how many mice were in the study nor how much less they weighed than the control group at the end of the trial.

The release also provides what it calls molecular detail about benefits to the experimental fasting mice vs. the control mice. But again, the quantities and context are not there.

“Through an analysis into the underlying biology involved, the researchers found that such intermittent fasting tempers an immune reaction in fat cells. There are changes in certain gene pathways involved in the immune system and the body’s reaction to inflammation. A type of white blood cell known to play a role in fighting inflammation is triggered. Known as anti-inflammatory macrophages, these cells stimulate the fat cells to burn stored fats or lipids by generating heat. This happens during periods of intermittent fasting because there is an increase in vascular growth factor (VEGF) that help form blood vessels and activate anti-inflammatory macrophage.”

What are the changes? How were they measured? We don’t see any numbers in this description to help the reader evaluate the credibility of the data.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The release does not mention any potential harms that could exist for intermittent fasting.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

While the published study discussed the study limitations and the “practicality” of doing similar experiments with humans, the news release doesn’t acknowledge any limitations or explain to readers that animal studies are rarely replicated in humans and that much more study was called for by the authors to examine if “(1) beneficial effects of IF last after stopping the fasting (i.e., if there is a rebound effect); (2) whether there is any potential harm of IF; and (3) whether IF benefits apply to all generations (i.e., an age-dependent issue) and disease conditions.”

Does the news release commit disease-mongering?


There was no disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The research was funded by a variety of grants which were listed in the sidebar of the EurekAlert! site, but not in the news release text. The authors declared in the journal article that they had no conflicts of interest.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

While the release is written as if it could help inform human obesity treatment or prevention, there is no discussion of how obesity is treated or prevented now and the many alternatives available. These include changes in exercise and diet patterns and bariatric surgery.

Does the news release establish the true novelty of the approach?


The release does not make a claim of novelty. In the journal article, the authors write that others have established the ability of intermittent fasting to promote weight loss. They do say that they have identified a mechanism that might explain why weight loss occurs in fasting mice which could be considered novel.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Not Satisfactory

We think the headline is stretching things by stating “On and off fasting helps fight obesity.”

The average reader likely assumes the obesity referred to is in humans and not mice. The release doesn’t clarify that the study was only in mice until the fourth sentence.

“Up to sixteen weeks of intermittent fasting without otherwise having to count calories helps fight obesity and other metabolic disorders. Such fasting already shows benefits after only six weeks. This is according to a study by Kyoung-Han Kim and Yun Hye Kim in the journal Cell Research which is published by Springer Nature. Intermittent fasting in mice helped to kick-start the animals’ metabolism and to burn fat by generating body heat. The research team was led by Hoon-Ki Sung of The Hospital for Sick Children in Ontario, Canada.”

Total Score: 3 of 8 Satisfactory


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