What I’ve Learned About Longevity — And Why I Now Eat Once a Day Nutrition and Our Hybrid Bodies In 1950, my friend Bill — a brilliant engineer — built an unusual car.

Its primary fuel was electricity, with gasoline used only when available as a backup.

It was perfectly fine to use gasoline once every couple of days or even less often.

But people kept running it on gasoline about 90% of the time.

As a result, the car broke down frequently.

Bill kept telling everyone, “Use it the way it was designed!” Despite his advice, people came up with their own theories about the “right” way to operate it.

Eventually, Bill went bankrupt and left the car industry.

This situation my poor (imaginary) friend Bill found himself in is exactly like our modern health environment.

How did eating become so complicated?

Most of us just want to feel good, look good, and live a long life.

You’d think that by now there would be clear consensus on what our eating habits should look like.

Instead, we’re faced with countless competing ideas.

Should we follow Diet ABC, Diet XYZ, or something in between?

One of the earliest known diets was proposed by a man named George Cheyne in 1724.

Today, you can find over 50,000 different books on the subject on Amazon.

Like Bill’s car, there must be a simple way to fuel our bodies that best matches how they were designed.

We’re obviously not engineers, but we are Homo sapiens.

We’ve been around for about 200,000 years, and for most of that time, our food environment looked nothing like it does today.

Agriculture didn’t exist for the first 190,000 years of that period.

Even the fruits and vegetables we eat now are nothing like their wild ancestors — we’ve selectively bred them to suit our tastes.

Just 700 years ago, bananas looked completely different.

So what kind of eating pattern were we adapted to?

For most of human history, the environment chose our diet for us.

Your choices were simple: eat what was available, or die.

The idea that our bodies adapted to a certain mix of nutrients available in the environment isn’t new.

It’s become well-known recently thanks to the “Paleo diet.” But what I want to get at is that our bodies also had to adapt to when food was available.

There must be a natural frequency of eating that promotes health and longevity.

Where to Begin?

It seems logical that more food would make you healthier and help you live longer.

But let’s look at this from “first principles,” as Elon Musk describes it: “It’s easier to reason by analogy rather than from first principles.

First principles is a kind of physics way of looking at the world.

You boil things down to the most fundamental truths and say, ‘Okay, what are we sure is true?’ And then you reason up from there.

It takes a lot of mental energy.” So what do we know for sure about longevity?

Besides exercise, words like “superfoods” might come to mind.

Maybe more omega-3s, some red wine, taking supplements, or drinking less alcohol will help us live longer.

There are many factors, but science has identified one reliable way to consistently increase lifespan: If you take any creature on Earth — from yeast cells to spiders, insects, rabbits, or dogs — and reduce their calorie intake by 30%, they live about 30% longer.

The one creature that hasn’t been rigorously tested this way yet is modern humans (Homo sapiens).

Let’s start there.

For a long time, conventional wisdom said you needed three balanced meals a day to stay healthy.

Since childhood, “breakfast, lunch, and dinner” has felt as natural as sleeping or going to the bathroom.

Breakfast was the most important meal, you needed a good lunch to focus during the school day, and going to bed without dinner was considered child abuse.

It’s the same in Japan, where I now live, and around the world.

If we want to reduce calories for longevity while sticking to three meals, the only option is to eat less at each meal, right?

But where did the idea of three meals a day come from?

As food historian Abigail Carroll explains in her book Three Squares: The Invention of the American Meal, eating three meals a day was largely a cultural invention.

When European settlers arrived in America, they found Native Americans eating whenever they felt like it, not at set times.

The Europeans saw the lack of scheduled meals as uncivilized and changed it.

In short: the three-meal model is not based on our biological needs.

How Our Environment Designed Us In hunter-gatherer cultures, it was completely normal to eat a big kill and then go for long periods with very little or no food until the next major source of fat and protein appeared.

In fact, if our ancestors couldn’t handle that, we probably wouldn’t be here reading about diets today.

The Pirahã people, an indigenous group in the Amazon rainforest studied extensively by anthropologist-linguist Daniel Everett, don’t eat every day — and they don’t even try to.

They knew about food storage techniques but rarely used them except to trade with Brazilian merchants.

When asked why they didn’t store food for themselves, they replied: “I store meat in my brother’s belly.” Before agriculture, eating three meals a day — or even eating every day — was often impossible.

Some might point out that life expectancy in the Stone Age was much lower (around 33 years) as proof that modern eating habits are healthier.

However, infant mortality was a huge factor dragging that number down.

Thanks to modern civilization and technology, even those who are less resilient or have weaker genetics can survive.

As Doug McGuff notes about life expectancy back then: It wasn’t about metabolic balance or long-term health benefits.

Fossil evidence from elderly survivors — based on ligament attachments, bone wear, and mineral density — shows they were extremely robust and strong.

Glucose Metabolism and How “Conventional Wisdom” Has Hurt Us A widespread misconception is that stable blood sugar is essential for survival, which supposedly justifies the biology of three meals a day.

Bear with me for a bit of biochemistry to understand why constantly consuming carbohydrates to maintain blood sugar isn’t just unnecessary — it can create a harmful, vicious cycle.

When you eat carbohydrates (bread, pasta, sweets, whatever), glucose enters your bloodstream and insulin is released to distribute it properly.

Through insulin receptors, glucose enters cells to produce energy.

This can only happen at a certain rate, so to avoid flooding the cells or leaving excess glucose in the blood, about 70 grams can be stored in the liver and 200 grams in the muscles.

So after eating bread in the morning with your coffee (or whatever vanilla latte nonsense you have), you store all the glucose you can.

The excess has to go somewhere — into your body fat.

Your body stores it there because fat cells have less complex mechanisms than other cells.

Excess glucose can also bind to proteins, interfering with cellular function in a harmful inflammatory process called glycation.

It’s like pouring sugary syrup into a car engine.

The problem is that when your energy levels drop, you can’t easily access the energy stored in your body fat because the hormone responsible (hormone-sensitive lipase) is inhibited by insulin.

High insulin from processing all that glucose prevents you from burning fat for energy.

If you have a lot of insulin circulating and now need energy, you’ll feel intense hunger.

You’ll need a quick snack to raise blood sugar and restore your energy levels short-term.

This is why, if you follow the standard recommended American diet, you often get stuck in a constant cycle of craving food whenever blood glucose dips — making three meals a day feel absolutely necessary.

Even Dr.

Peter Attia fell into this trap: Despite exercising 3–4 hours a day and following the food pyramid to the letter, he gained a lot of weight and developed what’s known as “metabolic syndrome.” The Rescue: Ketosis If you stop consuming glucose for 10–12 hours, your glucose stores run out and your body begins breaking down fat.

The liver then produces molecules called ketones.

Ketones provide energy to cells through similar pathways as glucose, but they are more stable, efficient, and don’t cause the complications we discussed.

You may have heard ketosis referred to as “starvation mode” in school, but that doesn’t mean you’re on the verge of actual starvation.

I don’t like that term because it implies glucose/carbs are the body’s primary fuel, when humans can live perfectly well without any carbohydrates.

“Humans have no dietary requirement for carbohydrates.

Not even one gram.

We have this amazing liver that produces glucose whenever we need it.” A striking example: A 27-year-old Scottish man weighing 456 pounds fasted for 382 days, consuming only water and vitamin supplements.

He lost 276 pounds and completed the fast with no ill effects.

Technically, he was in “starvation mode” the entire time, yet his body used its fat stores for energy.

(Note: Nutritional ketosis is very different from diabetic ketoacidosis.) Several years ago, when I first heard about low-carb diets, I was skeptical.

Honestly, when I learned that my close friend’s mother was trying the Atkins diet, I was worried about her.

But after understanding the biochemistry behind it, I started following the Paleo diet.

I felt great overall, my fitness improved with less effort, and my energy levels became much more stable.

The downside was that planning meals was annoying, so I cheated quite often.

The Benefits of Fasting Even in environments where people could eat multiple times a day, the concept of fasting for health benefits has persisted for a long time.

There’s an inscription on an Egyptian pyramid from around 3800 BC that says: “Humans live on one-quarter of what they eat; the other three-quarters live on the doctor.” Plato fasted to increase mental efficiency.

“Medical Luther” Philippus Paracelsus called fasting “the greatest remedy.” Mark Twain suggested fasting was more effective than any medicine.

The Romans even believed they could cure people possessed by demons by locking them in a room without food.

Fasting and Aging To simplify an incredibly complex process: Aging is essentially the accumulation of damage to your DNA.

Geneticist Professor David Sinclair and his team found that not eating activates sirtuin proteins, which are directly responsible for DNA repair and are considered a key factor in longevity.

Neuroscience professor Mark Mattson at Johns Hopkins University has shown how fasting stimulates the growth of new neurons in the brain.

This helps explain why fasting is linked to protection against neurological diseases like Parkinson’s and Alzheimer’s.

This information got me excited about intermittent fasting.

With 16:8 intermittent fasting, you don’t eat for 16 hours a day.

This gives your body time to deplete glucose stores, start burning fat, and reap the benefits discussed above.

Many sources suggest that the key factor — whether through prolonged fasting, intermittent fasting, or simply eating less — is giving your body a chance to exhaust glucose stores and enter ketosis, leading to the health benefits mentioned.

I realized I could achieve similar effects to the Paleo diet with more dietary freedom.

The problem with intermittent fasting was that I still craved food outside the 8-hour eating window, and I had to be somewhat strict about what I ate — though not as strict as with three meals a day.

Trying One Meal a Day Upton Sinclair (born in the late 1800s and lived into his 90s) published a book in 1911 called The Fasting Cure.

It was inspired by the personal experiences of 250 people who reportedly cured various ailments through prolonged fasting — from colds and headaches to constipation, arthritis, heart valve disease, and even cancer.

Dr.

Alan Goldhamer described how in 2012, a 42-year-old patient with stage 3 lymphoma went into remission after a 21-day fast.

All of this inspired me to try my first week-long fast… but I stopped on day four, even though I didn’t feel bad.

Although I missed my goal and didn’t notice huge differences immediately, a few days later I realized something: I used to enjoy refined sugar occasionally, but after the fast, I had no interest in it.

It was like my taste buds had been reset.

Around this time, I discovered a book by Dr.

Yoshinori Nagumo titled Kuufuku ga hito o kenkou ni suru (“Hunger Makes People Healthy”).

It makes an incredibly compelling case for limiting yourself to one meal a day.

The book covered many of the points I’ve discussed here, plus some I hadn’t, and dispelled worries like malnutrition.

It was also easy to trust him — he’s about 30 years older than me but looks younger.

I decided to try eating once a day for two weeks.

For the three weeks before starting, I was showing my sister around Tokyo and eating anything and everything that looked good.

I started the Nagumo plan the day after she left.

The first three days were definitely the hardest.

Around 11 a.m., I realized I wasn’t getting the usual pleasure from food at that time of day and felt a strong urge to eat.

My stomach wasn’t actually hurting — it was more like not being allowed to play video games after school.

By about 4 p.m., I was convinced I was really hungry and needed food.

Waiting another 30 minutes until 4:30 felt like the final reps of a brutal squat set.

The next two days were a bit easier.

On day four, I noticed I wasn’t constantly checking the clock thinking, “Ah… only four more hours until food!” After a week, I tested the system by cycling 50 km from Tokyo to Atsugi.

I wasn’t training much at the time — my usual bike rides were only about 3 km.

It was tough, as expected, but I didn’t feel physically weak.

I felt hunger pangs earlier than usual, but I didn’t feel any loss of strength from lack of food.

That convinced me to stick with one meal a day.

It’s now been a month since I started, and I feel fantastic overall.

My energy levels are extremely stable, I feel more focused, and strangely, I have fewer hunger issues than with intermittent fasting.

Even if I don’t eat a perfectly healthy meal, I can now feel confident that my body has plenty of time to clear out excess glucose or any toxins I consumed.

The only time I crave unhealthy food is when I’ve had some alcohol.

Looking back, it’s hard to imagine stuffing my stomach with food multiple times throughout the day.

Beyond the health benefits, another reason I do this is the same reason Steve Jobs wore the same outfit every day: it simplifies choices and frees up mental energy to focus on other things.

At least for me, the amount of new information I gain has only a small effect on behavior change.

For example, if my knowledge of alcohol’s harms increases by 60%, I might only reduce my consumption by 30%.

With this article alone, I don’t expect you to suddenly start eating once a day.

But I hope it encourages you to give your body a break and eat when you actually need to — not just because the clock says so.

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