Calorie restriction vs. intermittent fasting

When I was in law school twenty-something years ago, a landlord tried to keep my full $2,000 security deposit by claiming I had broken some flimsy freestanding cabinet in the bathroom. Her approach always struck me as naïve. She knew I was a law student, and that I would be itching to try out my new legal skills. The end of the story is she didn’t show up at the small claims court hearing — an automatic default — and she mailed back my security deposit a few days later.

Something similar is happening on social media over disagreements of every kind. On Twitter in particular, you have the algorithm picking up and blasting out the opinions of high-profile generalists. Lurking in the background are fanatical niche experts who are itching to draw attention to themselves and increase their follower count. Influencers who fire off careless tweets risk 1) crossing in front of some random buff and his area of specialization, and 2) getting debunked by devil’s advocates who can google around and query ChatGPT to source evidence to the contrary.

As an aside, there is growing popularity around the idea of having a physical venue in Las Vegas where online adversaries can settle their beefs in person. The 24/7 streaming of confrontations between keyboard warriors would be the most popular broadcast of all time.

In any event, a lightning rod issue on health Twitter is whether intermittent fasting delivers any additional metabolic benefits compared to plain calorie restriction (a diet). The calorie restriction side is genuinely hostile towards those, like me, who fast. I think they feel so strongly because they see intermittent fasting as a conspiracy theory.

Just yesterday, I came to the aid of a small account on Twitter. He was under siege from a guy with 200k followers — a massive account who boasts about having a PhD in Nutritional Sciences (whatever that is), and whose followers include celebrities like Joe Rogan. This influencer was punching down because the poor guy suggested that fasting could slow aging. The nutrition doctor replied tersely: “There is no evidence to support your claim.”

Well, let’s take a deeper look.

For starters, few studies exist on intermittent fasting, and there are almost none on how intermittent fasting compares to a low-calorie weight loss plan. The reality is that researchers struggle to recruit large cohorts willing to go hungry for weeks or months.

If there was ever a moment to adopt my paradigm of common sense observations, this is it. Here’s what I see:

  1. For all of human history, food was scarce, difficult to obtain, and hard to preserve. The custom of three meals per day emerged only during the industrial revolution when workers ate a meal before leaving for work.
  2. Going long periods without food will have a more profound impact on insulin and autophagy than several reduced calorie meals daily. Every time you eat you’re going to trigger an insulin response (unless it’s fructose or pure fat). The fewer meals you eat each day, the less insulin your body will produce. Autophagy, the body’s cellular renewal process, is triggered when the body shifts its energy metabolism from glycogen (the stored form of glucose) to ketones. If you’re eating multiple meals, you’re interfering with this process.

I tweeted at the bully doctor of nutrition: “There is a lot of evidence to support intermittent fasting to boost autophagy, and fewer insulin spikes/lower fasted insulin … all important for slowing aging.”

The doctor replied: “Ok. Cite them. And cite the ones that show it’s better when compared to normal calorie restriction & exercise. I’ll wait [laughing emoji].”

At which point I broke out the bibliography in Dave Asprey’s book Fast This Way, and asked ChatGPT about studies that compared intermittent fasting to calorie restriction.

After about 30 minutes, I was ready to respond to the nutrition doctor.

I replied: “Not many studies exist on IF vs. calorie restriction because it’s difficult to get subjects to adhere to an IF diet long term. However —

Women in both groups lost a similar amount of weight, but those on the 5:2 [fasting two days per week] diet lost more abdominal fat and exhibited a greater improvement of insulin sensitivity compared to those on daily calorie restriction.

Nevertheless, intermittent fasting resulted in beneficial effects that met or exceeded those of caloric restriction including reduced serum glucose and insulin levels and increased resistance of neurons in the brain to excitotoxic stress. (Mice study)

We demonstrate for the first time in humans that eTRF [early time-restricted fasting] improves some aspects of cardiometabolic health and IF’s effects are not solely due to weight loss.

In conclusion, these preliminary findings highlight underlying differences between IER [intermittent energy restriction] and CER [continual energy restriction], including a superiority of IER in reducing postprandial lipaemia [post-meal circulating fat], which now warrant targeted mechanistic evaluation within larger study cohorts.

I guess I’ll see this guy in Vegas.

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