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  • Writer's pictureAndy De Santis, RD MPH

Intermittent Fasting – The Most Popular Trend of 2021?

As I mentioned in my first piece for Nutrioso, intermittent fasting has indeed surpassed the keto diet as the most popular “diet trend” – at least according to a survey of dietitians anyway.

This revelation doesn’t particularly surprise me, given the natural ebb and flow of such trends and also the relative sustainability and dynamism that intermittent fasting entails as compared to the ketogenic diet which, by default, removes access to about half of the foods in the food system.

My goal with today’s article is to provide a brief insight into how I broach the topic of intermittent fasting with clients and also to highlight some of the more recent and higher quality studies done on fasting in an experimental setting.

Independent of your default views on intermittent fasting, it remains a hot topic in modern nutrition discourse and the ability to speak about it at a high level will surely enhance your reputation among clients who wish to cover it with you.

Let’s get right into it.

Intermittent Fasting – My Views

The rise of local pro-fasting medical figures like Dr. Jason Fung has made it increasingly likely that your clients have been exposed to fasting content in some capacity, and as a result harbour some curiosity about it.

This is certainly my professional experience.

In practical terms, the most popular and commonly utilized form of fasting is the sort of cliché 16:8 daily fast which ultimately amounts to not much more than skipping breakfast.

Rarely may clients be intrigued by longer periods of fasting and I always make a point to underline that one’s dietary pattern as a whole will always supersede the presence or absence of a fasting regimen. Even so, some individuals are compelled to incorporate fasting into their routine and many do so with some measure of success depending on its appropriateness for their lifestyle and their own personal characteristics.

Certainly, there are individuals for whom this paradigm facilitates a different way of looking at arranging one’s day, around which could lead to benefits for the right person.

I also will be honest in saying that the current state of the evidence (as well as the importance of good mental health and a strong relationship with food) does not justify bending over backwards to engage in intermittent fasting when it isn’t abundantly clear that it leads to an improvement in one’s quality of life and dietary pattern.

Intermittent Fasting – Recent Experimental Evidence

As most nutrition trends do, fasting has ridden a wave of anecdotal and theoretical scientific inquiry that promises certain benefits such as cellular revitalization, enhanced “fat” burning and just about everything in between.

But as we move away from theory to practice, some of the early experimental studies on fasting have been less than compelling.

Multiple randomized controlled trials (1,2) have failed to demonstrate a unique effect of fasting on body weight or cardiometabolic markers when the host of other relevant variables were properly controlled for.

It is very hard to say right now, (individual preferences aside) that an equally strong dietary pattern will be enhanced by intermittent fasting.

Yet proponents of fasting do allude to other unique benefits. Although I’ve not yet encountered high quality experimental evidence to support these claims, it has been demonstrated in a limited capacity that intermittent fasting may alter less traditionally studied biomarkers such as lipid metabolism, gene expression and mitochondrial functionality – but better evidence will be required to before such claims can be made with any level of confidence.

Final Thoughts

The state of the evidence suggests fasting is not an essential tool to promote good health and will probably never represent a more important consideration than one’s dietary pattern unless for a particular individual an intermittent fasting regimen drastically alters how they interact with food for the better.

Hope you enjoyed today’s article!

-Andy De Santis, RD MPH


  1. Templeman I, Smith HA, Chowdhury E, et al. A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults. Science Translational Medicine. 2021;13(598). doi: 10.1126/scitranslmed.abd8034 (Abstract only)

  2. Kunduraci YE, Ozbek H. Does the Energy Restriction Intermittent Fasting Diet Alleviate Metabolic Syndrome Biomarkers? A Randomized Controlled Trial. Nutrients. 2020;12(10):3213. doi: 10.3390/nu12103213 (Abstract only)


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