Let’s take a closer look at the last half century, because that’s the period over which our data are the most reliable—and during which these numbers have changed most dramatically.
by Stephan J. Guyenet
Following excerpts adapted from the author’s book, The Hungry Brain: Outsmarting the Instincts That Make Us Overeat, published by Macmillan Publishers
Stout but not quite obese, and boasting a prominent belly, Yutala would have been an unremarkable-looking man in many places. He would not have stood out on the streets of New York, Paris, or Nairobi. Yet on his native island of Kitava, off the coast of New Guinea, Yutala was quite unusual. He was the fattest man on the island.
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| Transparent skull model [Photo: Jesse Orrico/Unsplash] |
In 1990, researcher Staffan Lindeberg traveled to the far-flung island to study the diet and health of a culture scarcely touched by industrialization. Rather than buying food in grocery stores or restaurants like we do, Kitavans used little more than digging sticks to tend productive gardens of yams, sweet potatoes, taro, and cassava. Seafood, coconuts, fruits, and leafy vegetables completed their diet. They moved their bodies daily and rose with the sun. And they did not suffer from detectable levels of obesity, diabetes, heart attacks, or stroke—even in old age.
As extraordinary as this may sound to a person living in a modern society beset by obesity and chronic disease, it’s actually typical of nonindustrialized societies living similarly to how our distant ancestors might have lived. These societies have their own health problems, such as infectious disease and accidents, but they appear remarkably resistant to the disorders that kill us and sap our vigor in affluent nations.
As it turns out, Yutala wasn’t living on Kitava at the time of Lindeberg’s study; he was only visiting. He had left the island fifteen years earlier to become a businessman in Alotau, a small city on the eastern tip of Papua New Guinea. When Lindeberg examined him, Yutala was nearly fifty pounds heavier than the average Kitavan man of his height and twelve pounds heavier than the next heaviest man. He was also extraordinary in another respect: He had the highest blood pressure of any Kitavan examined by Lindeberg. Living in a modern environment had caused Yutala to develop a modern body.
Yutala is a harbinger of the health impacts of industrialization. His departure from a traditional diet and lifestyle, and subsequent weight gain, form a scenario that has played out in countless cultures around the globe—including our own culture, our own families, and our own friends. In the United States, we have a tremendous amount of information about the diet, lifestyle, and weight changes that accompanied this cultural transition. This will provide us with valuable clues as we piece together the reasons why our brains drive us to overeat, despite our best intentions. Let’s start by examining how our weight has changed over the last century.
THE COST OF PROGRESS
In New Guinea, as in many other places around the globe, industrialization has triggered an explosion of obesity and chronic disease. If we look back far enough, we can see traces of the same process happening in the United States.
In 1890, the United States was a fundamentally different place from what it is today. Farmers made up 43 percent of the workforce, and more than 70 percent of jobs involved manual labor. Refrigerators, supermarkets, gas and electric stoves, washing machines, escalators, and televisions didn’t exist, and motor vehicle ownership was reserved for engineers and wealthy eccentrics. Obtaining and preparing food demanded effort, and life itself was exercise.
How common was obesity among our American forebears? To find out, researchers Lorens Helmchen and Max Henderson pored through the medical records of more than twelve thousand middle-aged white Civil War veterans and used their height and weight measurements to calculate a figure called the body mass index (BMI). BMI is basically a measure of weight that is corrected for height so we can compare weights between people of different statures. It’s a simple measure hat’s commonly used to classify people as lean, overweight, or obese (a BMI below 25 is classified as lean; 25 to 29.9 is overweight, and 30 and above is obese). When Helmchen and Henderson crunched the numbers, they found something truly remarkable: Prior to the turn of the twentieth century, fewer than one out of seventeen middle-aged white men was obese.
The researchers then calculated the prevalence of obesity in the same demographic between 1999 and 2000 using data from the US Centers for Disease Control and Prevention. They found that it started at 24 percent in early middle age and increased sharply to 41 percent by retirement age. Side-by-side comparison of the data from 1890 to 1900 and 1999 to 2000 yields a striking contrast.
This suggests that obesity was much less common in the United States before the turn of the twentieth century, just as it remains uncommon in traditionally living societies today. Although obesity has existed among the wealthy for thousands of years—as demonstrated by the portly 3,500-year-old mummy of the Egyptian queen Hatshepsut—in all of human history, it has probably never been as common as it is today.
Let’s take a closer look at the last half century, because that’s the period over which our data are the most reliable—and during which these numbers have changed most dramatically. In 1960, one out of seven US adults had obesity. By 2010, that number had increased to one out of three. The prevalence of extreme obesity increased even more remarkably over that time period, from one out of 111 to one out of 17. Ominously, the prevalence of obesity in children also increased nearly fivefold. Most of these changes occurred after 1978 and happened with dizzying speed.
Copyright © Stephan J. Guyenet
Stephan J. Guyenet received a BS in biochemistry from the University of Virginia, a PhD in neuroscience from the University of Washington, and spent a total of 12 years in the neuroscience research world. His scientific publications have been cited more than 2,100 times by his peers. His most recent work investigates the neuroscience of eating behavior and obesity. Today, he continues his mission to advance science as a writer, speaker, and science consultant. He lives in the Seattle area, grows unreasonable amounts of potatoes, and brews a mean hard cider.
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