Intermittent fasting and aging slower

The benefits of restricted eating are myriad and powerful, if done right.

I’ve noticed that a lot of the online advice about intermittent fasting and its cousin, caloric restriction, is based on research on non-human organisms — mice, worms or yeast — or small groups of humans that the researchers invariably describe as “young and healthy.”

But what if you’re old and healthy? Or just older and deeply invested in staying as physically, mentally and physiologically strong as possible into your 50s, 60s and beyond? Is intermittent fasting, or caloric restriction, a practice you should embrace?

Some experts aren’t convinced intermittent fasting, or IF for short, does anything except help you drop a few pounds. I disagree with them, based on my and others’ experience, and in a brief audio follow-up to this post, I explain my reasons.

So, to the question about whether to embrace specifically IF, I think the answer for most healthy adults is a big, fat (pun intended), slightly qualified¹ Yes. Here’s why.

Intermittent fasting (IF) vs. caloric restriction (CR)

Intermittent fasting is the practice of limiting eating to within a specific daily range — say, 6 to 12 hours. Caloric restriction, by contrast, refers to reducing the overall amount of food you eat each day to a minimum, without limiting essential nutrients.

IF and CR each seem to emulate how humans have been wired to eat from the beginning: only when and if food became available.

Benefits and risks of CR

CR is more difficult to maintain over time and sort of rides the edge of human tolerances about what is, for many people, considered healthy. It’s not for dilettantes or most athletes (who need sufficient daily protein to avoid cannibalizing muscle tissue). CR is an advanced technique for people in good health who know their body’s needs very well².

But if you’re able and healthy — and even if you’re 45, 50 or 70 — several more recently studies have shown even modest levels of CR (12-15% reductions in daily food consumption) can lead to powerful health and longevity benefits, including:

• improved muscle strength even as it reduces muscle mass

• aging slower (though not necessarily reducing biological age)

• an increase in cellular housekeeping and repair functions (known as autophagy) that keep the bits of our cells, called organelles, functioning

• a reduction in oxidative stress that increases with, and causes us to, age

• lowered blood sugar, cholesterol and inflammation

But CR done wrong can lead to health problems, including an overkill of autophagy that can have harmful effects at a cellular level. For most of us, a more achievable, less onerous alternative with many similar effects on reducing the rate of aging is intermittent fasting.

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A note about my experiences with CR and IF: For a long time, before I knew there was a term for it, I practiced a casual form of daily CR — eating just enough to avoid feeling irritably hungry — on the theory that it just might, as early studies suggested, slow down my biological aging process. CR certainly made me leaner (and sometimes meaner, unfortunately, due to being “hangry”) with steady, durable levels of energy; I never felt midday fatigue or a need for an afternoon coffee. I was eventually persuaded by a coach to stop CR and start eating more, and more often, because I was most likely damaging my athletic performance and my ability to keep, much less build, lean muscle.

I’m now an IF devotee, not eating after 6:30pm and usually not before 10am, unless I’m hungry, in which case I listen to my body. I find IF, which takes a while (weeks, if not months) to fully acclimate to, very effective at staying lean, strong, durably energetic and sharp and, I hope, aging slower than my actual years.

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Benefits of intermittent fasting

If you can manage to not eat for even 12 hours (say, 7pm to 7am), you can succeed at IF. (In my non-expert experience, a daily eating window smaller than about 6 hours starts to feel like hardcore CR, especially if you’re exercising regularly.) Once you work your way up to 14 or 16 hours of fasting, eating only between mid-morning and mid-evening, your body begins burning stored fat and glucose for energy — yay! You may well lose a few pounds of flab, and then you’re on the glide path to many of the same benefits CR provides, including:

• improved brain health that, in research on animals, led to…

• a reduced risk of Alzheimer’s disease, Parkinson’s disease and stroke

• a reduced risk, according to research on animals, of cancer (perhaps the result of losing weight and lowering blood sugar and inflammation)

For women over 50, in particular, IF can have specific benefits that include weight loss and mitigating the effects of menopause. But show me a 50-year-old guy who isn’t also interested in having IF’s cellular-level housecleaning function slow down his aging process, and I’ll show you Wilford Brimley.

Practitioners in praise of IF

Moran Hermesh, a functional medicine dietician based in Santa Monica, Calif., practices IF herself and recommends the practice to her clients — regardless of gender. “It creates a lot of health benefits,” she told me in an interview for this article. “It really cuts out those extra calories after dinner that contributes to weight gain and inflammation.”

Can you practice IF and still exercise regularly, train hard, build muscle and operate and peak physical, mental and physiological levels? Definitively, yes, you can — if you eat the right foods and nutrients. To succeed at IF, eating consistently is crucial, Hermesh said. “In this 8-hour window, you do need to eat every two to three hours, 25 to 30 grams of protein.”

This is a process of learn-and-adapt that requires time to figure out. Hermesh says she teaches her clients to “only eat what your body needs” and “to be never hungry and never full.”

1. I’m not a doctor and this post is not medical advice. But if you’re pregnant, diabetic or have a compromised immune system or any other health issue, talk with your doc about all this.

2. see footnote 1.