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World’s Best Diet Part 9–Fasting

If you google the word diet, you will come up with over 200,000 results.  Every week, month, year, and decade a new study or article comes out claiming certain foods are killing us, or that some other food or nutritional approach will lead us to the promised land.  Unfortunately, articles are written to create traffic, so scientific research is often misreported or spun to sell magazines or generate website traffic.  The truth is, there are many ways to skin a cat.  All of the evidence on nutrition (in regards to weight loss) points to two undeniable truths.  First, that dietary adherence is king.  It doesn’t matter how perfect or evidence based a nutrition plan is, if you can’t follow it, it doesn’t matter.  Before starting any eating plan, you must ask yourself how easy it will be to maintain long term.  Second, you must achieve an energy deficit to lose weight (eat less energy than you expend each day).  Though “calories in, calories out” may be slightly over simplified, it is still the underlying rule to any weight loss success.   For any weight loss plan to work, you must consistently follow the pla, and you must be in a caloric deficit.  This series will highlight the nine most popular current nutrition approaches, and the pros and cons of each.


Claims: There are a ton of different approaches to fasting.  The most common are ADF (alternate day fasting) and IF (intermittent fasting).  ADF simply means that one day you eat nothing, followed by a day of standard eating.  IF is a restricted eating format where you don’t eat for a given period of time (16 hours being the most popular) followed by a feeding window where you eat regularly (8 hours in the 16 hour example above).  Every person fasts when they sleep by default, the various fasting protocols simply extend this fast one way or the other.  Purported benefits include improved insulin sensitivity, improved heart health, weight loss, better brain function, and some eve claim better performance.

Reality:  There is nothing magical about fasting.  When calories are controlled for fasting protocols seem to offer many of the health benefits that other diets show (improved heart health, improved insulin sensitivity, weight loss, etc.).  One unique potential benefit is that of life extension.  Several animal studies have shown this to be the case, but more research is needed.

Pros:No off limit foods.  Even without tracking food directly many people will eat less food by reducing the window of time in which they eat food.  This is probably one of the simplest plans to follow in concept.  If you can tell the time you can follow this plan.

Cons: No emphasis on food quality, or protein intake.  May not get enough vitamins and minerals in if you aren’t sure to emphasize getting a large amount of whole and unprocessed foods since you aren’t eating on a daily basis.  May be harder to maintain muscle mass (though research hasn’t shown this yet).  Could lead to binge eating behaviors during the feeding window in some individuals.  If this is you, this plan is not right for you.

Jeff Tirrell, CSCS, CFSC, Pn1