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Am I Technically Intermittent Fasting When I’m Sleeping?

I might be snoring, but I’m definitely not eating

One of these days, I’m going to learn not to discuss the food-oriented statements of my friends with my amazing wife, who is a dietitian at Duke University Hospital. Bringing my feeble meathead brain to a conversation with someone who has taken several graduate-level chemistry classes focused on nutrition is like showing up prepared to thumb wrestle and then getting taken down by a 7th degree jiu-jitsu black belt — I don’t stand a chance.

Case in point: On one occasion, I made the mistake of greeting my wife with the intermittent-fasting plan proposed by a friend of mine on Facebook as part of her surefire weight-loss strategy for the New Year. “I’m sick of people saying that they’re doing intermittent fasting,” grumbled my wife. “Everything is intermittent fasting! When you’re asleep, you’re not eating for long stretches of time, right? That’s intermittent fasting! You’re already not eating for eight straight hours during the night; why would you stretch it out even further?”

I totally backed off, and I refused to argue with my wife’s logic. After all, “breakfast” is literally breaking a fast imposed by your sleep schedule. So as far as I could tell, my wife was technically correct: Getting your ideal numbers of sleep every night is an acceptable form of implementing an intermittent-fasting strategy, inasmuch as intermittent fasting is impossible to concretely define.

Why is intermittent fasting so hard to define?

Primarily because no one ever had complete control over its definition, and its many different adherents were free to apply the term to many different dietary circumstances in an unregulated manner. A brief journey through the history of the way “intermittent fasting” has been applied will reveal exactly what I’m referring to.

The first popular use of the term I was able to track down was wedged into an edition of The Brooklyn Daily Eagle from February 1873. In an explanation of the healthy side effects to the Catholic practice of “eating eggs, fish and all kinds of vegetable food” during Lent, the unnamed writer of the section titled “The Secular Influences of Lent” referred to the 40-day practice of consuming one daily meal of approved food varieties as “intermittent fasting.” 

Despite the fact that this initial reference applied to the practice of abstaining from consuming food only for a specific period of time each day while still eating a solid meal on each of those days, the second major reference was utilized in a small November report from an 1899 edition of The Daily Independent of Coffeyville, Kansas, where a man’s attempt at a 120-day fast was referred to as “intermittent fasting.” Apparently, the fact that the man’s fast had a set beginning and ending was what qualified it as “intermittent.” 

From that point onward, the “intermittent fasting” appellation was casually assigned to any form of prescribed fasting. A 1902 report in The Seattle Star spoke of the intermittent fasting engaged in by a man who lost more than 200 pounds in one year by ingesting only one weekly meal for a year straight (and also reducing his cigar usage from 20 per day down to just one). I don’t know which I find harder to believe: The fact that this guy only consumed 52 meals in one year, or the fact that anyone would refer to such a practice as intermittent fasting. If anything, since this gentleman’s daily norm was to not eat anything at all, his lifestyle would have been more accurately described as “intermittent non-fasting.”

Okay, but these are all references from more than 100 years ago. Is there anything more recent?

I’m getting there! Sheesh…

The 1960s appears to have been when extreme dieting hit the mainstream. In an Associated Press story from 1962, it was reported that Dr. Garfield G. Duncan addressed his peers at the American Medical Association’s annual meeting and praised the effectiveness of medically supervised periods of intermittent fasting lasting up to 10 days, primarily because day one of the fast dispensed with the appetites of most of his patients. 

Perhaps seizing upon Duncan’s advice, Dr. Marshall Mercer opened the Bermuda Inn in Lancaster, California, where he was interviewed by The Boston Globe four years later regarding the weight-loss success his patients had achieved while having their caloric intake restricted to a scant 100 calories per day.

When Mercer was interviewed again in 1971 — this time by the Cincinnati Enquirer — he took credit for helping to cure more than 10,000 overweight patients of their obesity. The restrictions previously imposed by Mercer’s program had been loosened by that time — patients were permitted two days of 150-calorie consumption followed by an “eating day” of 800 calories. The weight-loss plan called for patients to consume no more than 3,000 total calories per week. But with no requirement given as to the times in which those calories could be eaten, this form of intermittent fasting appears to have been characterized more by its prescribed period of strict calorie limitation as opposed to the specific duration of time in which food consumption was prohibited. 

For what it’s worth, Duncan amended the definition of intermittent fasting by 1965 so that it would usually apply to just one day per week of strategic fasting, as reported by The Hartford Courant.

It sounds like they were still working out the definition of “intermittent fasting” even then.

Whoever “they” is, they still don’t have a consistent definition for “intermittent fasting” worked out to this day.

In a 2009 edition of the L.A. Times, during an article discussing the benefits of occasionally suffering through entire days without food, endocrinologist Marc Hellerstein stated that when it comes to intermittent fasting “the idea is that maybe you can trick the system to think it’s starving, but not make it starve every day.” Four years later in the Chicago Tribune, it was unequivocally stated that intermittent fasting is the practice of eating regularly five days a week, but then consuming a drastically reduced number of calories two days per week. This definition was attributed to Mark Mattison, chief of the laboratory of neurosciences at the National Institute on Aging, and it was implied that his definition of intermittent fasting didn’t require any specific abstentions from food at set times, and merely necessitated severe caloric restrictions two days out of the week.

The extent to which the waters of intermittent fasting had been muddied is evidenced by a 2014 editorial from McKenzie Hall in The Environmental Nutrition Newsletter. In a statement that appears to have been one part appeasement and two parts acquiescence, Hall writes that “intermittent fasting” can take many forms, “including significant restriction of one’s daily caloric intake, skipping a few meals during the week or completely avoiding food for up to 24 hours during a specified period of time.” 

With this level of open-endedness, “intermittent fasting” can be used to label nearly any form of dieting as long as it results in a significant overall reduction in daily calories, or concludes with at least one meal being skipped or forces the dieter to endure identifiable stretches of a day that are marked by a notable lack of eating.

So there is no one-size-fits-all definition of intermittent fasting?

That’s precisely the point: There is no consensus as to what constitutes intermittent fasting, and many of the definitions for intermittent fasting play fast and loose with the definitions of both “intermittent” and “fasting.” 

So to my wife’s point as to whether or not someone is engaged in intermittent fasting while they’re sleeping: Since bedtime represents a stretch of one-third of the day in which no food consumption is taking place — or at least it should — there’s no reason why that can’t be considered intermittent fasting. 

After all, per the definitions for “intermittent fasting” provided above, anyone who habitually oversleeps and then hurries off to work without eating breakfast is engaged in intermittent fasting, as is the workaholic who rarely breaks for lunch. If seemingly every other form of “dieting” gets subsumed within the intermittent-fasting category, why not a category for those who simply enjoy making the most of their beauty rest?