Why We Need to Feel Hungry Again

Humans evolved in a landscape of feast and famine. Our weight vacillated with the seasons and what nature offered to us. Thankfully we’ve mostly lost the forced famine. But we now seemingly have only two variations of feasting. We’re either kind of feasting, where we maintain our weight, or we’re definitely feasting, where we add weight. Hunger is missing from our daily, weekly, monthly, and yearly wellness prescription.

Rarely feeling real hunger is a strong sign that a person is suffering from the ill effects of comfort creep, according to a surge of new scientific evidence.

The data shows that we don’t typically gain weight in a linear fashion, like a quarter pound each month for a total of three pounds at the end of the year. Most of us maintain our weight most of the year, then experience periods of gain, according to a study in the New England Journal of Medicine. Scientists have identified big stressors, like getting married, moving, and the holidays, as times where people are most likely to pack on pounds. (We often frame stress as always negative. But stress can also be positive, such as celebrations.) For example, the subjects in the study didn’t gain much weight in the fall before Thanksgiving or in the months after the New Year. They did, however, put on anywhere from one to five holiday pounds. And the critical point was that the participants never lost that weight.

Anthropologists and historians know that our ancestors experienced persistent hunger. But despite what some paleo diet books will have us believe, early humans likely didn’t go for extended stretches without a single calorie. A day at most. And that was rare, according to food historians at Yale.

But it is agreed that these people weren’t eating around the clock. The research suggests they likely ate one or two meals a day. And between meals they surely weren’t snacking on vending-­machine foods or sipping Frappuccinos.

Most modern people, on the other hand, start cramming in calories upon waking up and don’t stop until right before bed, Satchin Panda, PhD, a scientist at the Salk Institute for Biological Studies, explained. One of Panda’s studies found that the average person now eats across a 15-­ hour window. Research from the University of North Carolina discovered that we’re snacking 75 percent more than we were before 1978. Our snacks are also 60 percent larger and more likely to be ultraprocessed.

The effects of this consistent stream of sugar, salt, and fat and our two versions of feasting are compounded over time, wrote the researchers in the New England Journal of Medicine study. “As this gain is not reversed during spring or summer months,” they concluded, “[this] weight gain appears likely to contribute to the increase in body weight that frequently occurs during adulthood.” Our growing disconnection from hunger is one of the critical reasons obesity began its rocket-­like rise in the late 1970s.

Beyond weight, the trouble with rarely feeling real hunger is that our bodies evolved to leverage lean times for good. Lean times are, in fact, a necessary state for optimizing long-­term health. This is because a hungry human body undergoes a sort of cellular natural selection.

We fully metabolize our last meal after 12 to 16 hours, depending on how much we ate. That’s when our body releases testosterone, adrenaline, and cortisol: a symphony of hormones that act as signals to burn stored tissues for energy. But we don’t burn our finest tissues. “We get rid of a lot of dead and damaged cells,” said Panda.

Over the years, many people have theorized that stretches without food could help prevent and even fight back against diseases like cancer. In the early 1990s we figured out why there may be a nugget of truth in these old claims.

 

How Constant Eating Disrupts Autophagy — and Leads to Disease

In 1992, David Sabatini, PhD, MD, a biologist at MIT, discovered what’s called the mTOR pathway. He told me to think of it as a general contractor, signaling to the body to demolish its old cells and replace them with newer, healthier ones. The body’s oldest cells have all sorts of problems and are implicated in many of the diseases that end up killing us.

“You couldn’t fully renovate the old house by bringing in only a plumber, or only an electrician or roofer or drywall guy,” he said. “You’d need to hire a general contractor, who would hire all those specialists, who would then come fix all those problems that needed to be fixed.”

The mTOR pathway senses whether your body is fed or not fed. When you go without food the contractor calls in all his workers. “It’s the one way you can trigger a whole series of events that are rejuvenating and antiaging,” said Sabatini. Your body is ruthlessly efficient, and it culls the herd by consuming your oldest, weakest cells. A researcher at Cedars-­ Sinai Medical Center calls this process your body’s way of “taking out the trash.”

These trash cells are ones that no longer divide and are thought to drive aging and disease. A study in Nature said that these cells “disrupt normal tissue function.” They cause inflammation, kill healthy cells, induce fibrosis, and inhibit the function of beneficial growth cells. These trash cells “actively damage the tissues in which they reside and can be directly linked to features of natural aging,” said the scientists. They’re also associated with cancer, Alzheimer’s, infections, osteoarthritis, excessive blood sugar and blood lipid levels, and more.

The body’s “taking out the trash” process is officially called autophagy, which translates from ancient Greek as “self-­devouring.” Autophagy is, in many ways, a metaphor for what happens to all things under discomfort: Our weak links —­ whether physical or psychological —­ are painfully sacrificed for our good.

Humans probably developed autophagy in concert with day and night cycles, generating what Panda calls circadian rhythms. The research suggests that the body has programmed within it a code to crank up autophagy to repair and rejuvenate itself at night, as it burns through the day’s food.

But our 15-­hour daily eating windows disrupt the process, said Panda. They rob our bodies of the 12 to 16 hours we need to fully metabolize food and lapse into autophagy mode. Or, as the Cedars Sinai scientist put it, “If you eat . . . before bed, you’re not going to have any autophagy. That means you’re not going to take out the trash, so the cells begin to accumulate more and more debris.”

A team of scientists from 16 different institutions including Harvard and Johns Hopkins who studied the topic wrote, “For many of our ancestors, food was probably scarce and primarily consumed during daylight hours, leaving long hours of overnight fasting. With the advent of affordable artificial lighting and industrialization, modern humans began to experience prolonged hours of illumination every day and resultant extended consumption of food.”

 

Can Fasting Lead to Increased Focus and Productivity?

Daily eating marathons also may have caused us to lose a step in our mental game. Somewhat paradoxically, a lack of food typically leads to a surge of energy. “The ability to function at a high level, both physically and mentally, during our extended periods without food may have been of fundamental importance in our evolutionary history,” wrote that team of scientists. This is likely why we often define the word “hunger” as not just discomfort from a lack of food but also as ambitious drive. It’s a drive that crosses animalistic distinctions.

“During [extended time without food], the body doesn’t shut down, it ramps up,” Dr. Jason Fung, a nephrologist and author of The Obesity Code, told me. “Think about a hungry wolf versus a lion who just ate. Which one is more focused? The hungry wolf.”

According to researchers at the University of Southern California, these advantageous responses to hunger first appeared billions of years ago in prokaryotes, microscopic single-­celled organisms that were the first life on earth.

We often define the word “hunger” as not just discomfort from a lack of food but also as ambitious drive. It’s a drive that crosses animalistic distinctions.

Recall the human hunger response of spurting hormones and burning fat. This gives the body energy from fat and from adrenaline, and adrenaline has been shown to increase alertness and focus, said Fung.

Today we don’t have to worry about needing the energy and mental acuity to, say, run down, track, and kill a dik-­dik. But we can still leverage hunger’s evolutionary chemical upsides to conquer our more modern goals. Hunger may help humans be more focused and productive in the tasks of modern life, according to Panda and Fung. Other research shows that people who stop eating a few hours before bed sleep better, said Panda. “So if you sleep longer and deeper, you’re likely to be more focused the next day.”

All this research is at odds with fad diet marketing, which has programmed us to ask, “What should I eat?” when we want to improve our health. Going without food and feeling some real hunger is often far more powerful.

We’re told, for example, that breakfast is the most important meal of the day (often in studies funded by, say, cereal companies). Yet little scientific evidence shows that it has any benefit over any other meal, according to research in the American Journal of Clinical Nutrition. And simply nixing breakfast hits the “sweet spot for practicality” in reacquainting a person with hunger, said Panda. It allows the body to go 12 to 16 hours without a calorie, which goes “a long way toward preventing diseases, increasing alertness and energy,” said Panda. And if a person eats a reasonable lunch they can enjoy a good-­size dinner without worrying too much about gaining weight. Getting off breakfast often sucks at first. But that’s only because the body and mind take time to adapt to change and initially miss sucking down food upon wake-­up.

Other research shows that programming two “hungry days” per week where we eat around 500 calories delivers benefits. A study in the International Journal of Obesity found that six months of this method led to more than 10 pounds of weight loss and health improvements in obese people. The catch is that a person can’t go crazy and pound food on their regular eating days.

Another option is to string together five “hungry days” in a row, once a month, eating just 700 total calories. A study in Cell Metabolism found that approach helped rejuvenate aging organs and increase the health span of mice.

And researchers at Harvard report that occasional 24-­hour stints without food can help reduce our appetite during our normal eating hours. This decreases average levels of insulin, a hormone that may determine the body’s “set weight.” The researchers also say these longer fasts may better stimulate cleaning out our old cells.

Rewilding our eating habits won’t be easy. It requires that we step back and become aware of how much and why we’re eating. It requires us to favor the foods humans have eaten for thousands of years but not be afraid of or feel guilty for the occasional comfort food.

Of utmost importance, it requires that we embrace the discomfort of hunger. We must recognize that occasionally going without food up to 24 hours is a normal and even beneficial human state. And we must also understand and adapt to the fact that much of our hunger isn’t real physiological hunger. Rather, it’s often a cheap coping mechanism to comfort us against the discomforts of modern life.

Excerpted from THE COMFORT CRISIS: Embrace Discomfort to Reclaim Your Wild, Happy Healthy Self by Michael Easter. Copyright © 2021 by Michael Easter. Used by permission of Rodale Books, an imprint of Random House, a division of Penguin Random House LLC, New York. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

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