Eating less as a way to live longer?

APRIL 17 — The first time I heard the phrase “zombie cells” was watching the reality TV show Limitless starring Chris Hemsworth (and directed by Darren Aronofsky) in which the Thor actor underwent experiments and trials in his search for habits which promote longevity.

In the third episode, Hemsworth and longevity expert Peter Attia (see Note 1) underwent a four-day water-only fast.

It’s here that Attia explains the value of caloric restriction (or CR) — which is bio-speak for, uh, eating nothing or way less than we normally do — and mentions that enigmatic term “zombie cells.”

Killing the zombies

If you google “autophagy” you’ll see that it’s the name given to a process by which our bodies perform a clean-up of weak or dying cells.

Meaning “self-eating” or “self-devouring”, autophagy represents:

“...the catabolic side of metabolism, when the cell stops producing new proteins and instead begins to break down old proteins and other cellular structures into their amino acid components, using the scavenged materials to build new ones. It’s a form of cellular recycling, cleaning out the accumulated junk in the cell and repurposing it or disposing of it.”

It’s like, instead of going to Mr DIY to get more fixtures to fix up our house, the contractor digs through the debris from our house and tears down spare materials which he can reuse to build new parts.

One of the materials our biological “contractor” rips apart are the so-called zombie cells i.e. old proteins and/or damaged cellular structures.

The act of fasting, by restricting the production of glucose and thus cutting off their supply to these cells, prevents their further growth and invites their eventual destruction and repurposing.

Voila! Our zombie cells die.

Conversely, by NOT fasting regularly or by stuffing our guts non-stop, we could be encouraging the spread of these impaired and substandard cells, thereby weakening our bodies as whole.

Birthing the ketones

When food is scarce, some of our fat is sent to our liver where it’s turned into an alternative energy source called ketones (from whence the term “ketogenic diet” derives).

According to Attia, ketones not only provide an energy boost, they also sharpen our mental focus.

Hence, in that particular episode in Limitless, an African tribe shares about how their fasting habits (practically “forced” as they don’t have supermarkets and mamak stalls where they live) improve their hunting prowess.

The point is that caloric restriction (basically cutting down on food without suffering malnutrition) can act as a surprising pick-me-up and health-booster. — Raluca Ioana Cohn/Getty Images/ETX Studio pic

I can’t speak for everybody else but I can attest that when I go without food for about 20 hours or more, I get a sort of cognitive clarity that I don’t get on other occasions.

Yes, often in such situations I remain hungry and irritated but my mind is clearer and sharper than normal. Could that be because my ketones are kicking in?

The point is that caloric restriction (basically cutting down on food without suffering malnutrition) can act as a surprising pick-me-up and health-booster.

Note 1: Attia published a book last month which is generating some positive attention. Attia, P (2023) Outlive: The Science and Art of Longevity.

*This is the personal opinion of the columnist.