We live in a culture obsessed with food. It's everywhere. Buildings formerly known as "gas stations" now tantalize customers with racks of junk food. On the same block, you can order stay-seated-on-your-tush fast food from your car. In every direction, you'll encounter Big Gulps, super sizes, and Extra Value Meals—more for less. But always more.
Health experts have a name for this environment: obesigenic. It's when food advertising, sedentary lifestyles, and often poverty conspire in a perfect storm to make us gain weight. And it works: More than two-thirds of adults in the United States are overweight or obese. Healthcare economists put the public toll of our expanding waistlines at nearly $210 billion per year, 21 percent of all health-care spending.
And that's just the tip of the iceberg. Some experts predict that soaring rates of diabetes and other weight-related ills could crater the U.S. economy by 2030. Worldwide, the McKinsey Global Institute places obesity directly behind smoking and war as the planet's most expensive bad habits—about $2 trillion per year.
Kinda tempts you to scream: "C'mon people! Quit shoveling down the calories!"
Except calorie reduction is not the answer. In fact, there's scant evidence that gluttony is our problem. Convincing data point to the other side of the calories in/calories out equation—physical activity. We're not eating too much, we're moving too little.
RELATED: Drop pounds, get fit, and eat better with the New Year, New You Challenge!
Last fall, determined to cut through the swirls of confusion surrounding the root causes of obesity, I read a half-dozen metabolism tomes and about 100 research papers on exercise, nutrition, and obesity. When my research was complete, I booked a flight to the Pennington Biomedical Research Center in Baton Rouge, Louisiana. The center has a worldwide reputation for its all-star faculty and meticulous studies.
My first day began at 6 a.m. when Pennington's executive director, Will Cefalu, M.D., met me for a pitch-black run around the research campus. Cefalu is a short, soft-spoken diabetes expert with a smooth stride who had, just 36 hours earlier, run Pennington's first Doc's Dash 5K. "Obesity is at the epicenter of the metabolic diseases, including diabetes, high blood pressure, and heart disease," he says. "That makes it a huge area of interest to all of us here."
After a quick shower and breakfast, I fiddled nervously before my first interview. For the last five years, I've been referring to Eric Ravussin, Ph.D., as "Public Enemy #1," even though I've never met him. He's a metabolism expert, who in 2009 told Time magazine: "In general, for weight loss, exercise is pretty useless."
Ravussin is not alone in his thinking. Among obesity experts, it's a nearly universal belief: Exercise is not a great tool for weight loss. Still, I secretly hoped that Ravussin would be asthmatic and wide as a piano bench. He's not. He's a spry 64-year-old with a lively glint in his eyes. That day, however, he hobbled toward me, one leg dragging behind the other. Even before we could greet each other, he offered an explanation. "I pulled a calf muscle at the two-mile mark of the Doc's Dash on Saturday," he says. "It was so bad I had to stop."
Hmmm, maybe I should re-evaluate his bad-guy status. An injured runner? Sounds honorable to me. Moments later, Ravussin was regaling me with stories about his track days in Switzerland. Ravussin, it turns out, is actually a big fan of running and exercise. "Exercise is great for your metabolic health, and for your weight maintenance down the road," he tells me.
However, he won't back off his Time statement. "Exercise isn't very useful for weight loss," he says. "You just can't burn enough calories—not as many as you can eliminate by diet."
This fact is illustrated in a popular YouTube video. One guy is running hard on a treadmill while his sidekick downs thick slices of pizza. Both count calories aloud. "That's five calories burned," pants the runner. A few moments pass: "That's 10 calories." Meanwhile, after each swallow, his friend crows: "That's one hundred calories, that's two hundred, that's three hundred, that's. . ."
The video is true to a point: We can consume calories faster than we can burn them. But diets don't work; they have a failure rate of 80 to 90 percent. It's not because people can't lose weight on them; it's because they can't stop the pounds from creeping back. As the researchers like to say: "Anyone can lose weight, but few can keep the weight off."
So okay, exercise doesn't work. Diets don't work. What, pray tell, does? The answer might be a thing called energy flux, where the secret is to move (read: run) more.
RELATED: Lose weight (and keep it off!) with Run Your Butt Off!
Energy flux is a new term for an old hypothesis. In the early 1950s, Harvard nutrition professor Jean Mayer, Ph.D., investigated the diet, exercise, and weight of 213 male laborers at the Ludlow Jute Company in West Bengal. The workers were divided into five groups according to the physical demands of their jobs: from sedentary (1), to light work (2), all the way up to "very heavy" work (5).
Mayer's results, published in 1956 by The American Journal of Clinical Nutrition, showed workers in groups 2 through 5 weighed about the same. These men somehow achieved a natural balance between calories in and calories out. The content of their diets didn't matter—what mattered was they ate just enough to satisfy their needs. Their weight remained healthy.
The sedentary workers in group 1 found no such balance. Despite sitting all day, they ate more than they needed, and grew fatter than the others.
Mayer deduced that humans have evolved to exercise a certain amount every day. When we do, all is well. A balanced body tells us how much to eat, just as it tells us how much to drink.
Unfortunately, the weight-control system appears to malfunction without daily exercise. When you sit most of the day, everything falls apart. "In his hundreds of thousands of years of evolution, man did not have any opportunity for sedentary life except very recently," Mayer wrote. "An inactive life for man is as recent (and as abnormal) as caging is for an animal. In this light, it is not surprising that some of the usual [metabolic] adjustment mechanisms would prove inadequate."
As obesity specialists have struggled to explain the failure of diets, they have increasingly championed Mayer's work, referring to it now as the energy flux hypothesis. The hypothesis says: Don't focus on reducing the number of calories you eat, or calories in. Focus instead on increasing the number of calories you burn, or calories out (by, of course, running more). In doing so, your body will find an ideal balance point that naturally promotes weight loss and will help you maintain a healthy weight.
James O. Hill, Ph.D., has spent 30 years in the exercise and obesity field. Back in 1994, Hill cofounded the National Weight Control Registry, and he's been tracking successful long-term weight losers ever since. On average, registry members have lost 66 pounds, and kept it off for more than five years. There is considerable variety among them, but most follow a low-fat, low-calorie diet. They also exercise a lot—more than an hour a day in many cases, which has led Hill to conclude that exercise represents the best way forward. "We believe that those who rely more on increasing physical activity than food restriction will be more successful in long-term weight-loss maintenance," he wrote in a 2006 analysis for Endocrine Reviews.
In a 2014 review of energy flux, epidemiologists Gregory Hand and Steven Blair agreed with others that exercise only slightly improved weight-loss results. In their paper in European Endocrinology, they noted that exercise nevertheless has an even more important health benefit: It has a profoundly positive effect on visceral fat and insulin sensitivity, two of the most important markers of metabolic well-being. "Energy flux, therefore, has an impact not only on weight change, but also on general health," they wrote. "An understanding of energy flux is crucial to the design of interventions to combat obesity. In fact, high energy flux appears to be an optimal strategy for maintaining weight while improving metabolic strategies."
In short, according to the energy flux theory, we shouldn't cut calories. Rather, we runners should increase total calorie turnover—calories in and calories out—to help our body find its balance point.
To understand why our future depends on moving more, consider our past. Specifically, the evolution—over 2 million years of human history—of the "work day," the roughly nine hours when humans scratch out a living. For 99.5 percent of those 2 million years, work (aka survival) meant hunting and gathering. Ten thousand years ago, we switched to subsistence farming; about 200 years ago, to industrial labor. A mere 35 to 40 years ago, we entered the digital age, and nothing will ever be the same. Now everything happens faster, we are all interconnected, and there's little reason to get up and move.
To a physicist, work is Force x Distance. Movement must happen, and it can be measured in calories burned. As hunter-gatherers, then as farmers, then as laborers, we burned lots of calories. Today we don't. It's inaccurate to say that we "go to work." In fact, we go to sit. We are not office workers; we are office sitters.
As a result, we burn far fewer calories during the work day than our ancestors did. Let's do the math. Physiologists measure relative work with a unit called the MET. When you are sitting, you expend 1 MET per hour, when walking slowly, 3 METs, when running slowly, 7 METs. Between sitting in the car, in meetings, and in front of the computer, the typical office person expends about 1.5 METs per hour.
It's safe to assume our forebears expended at least another MET per hour doing their real-work labor. What's the calorie out difference of one additional MET per hour over a 10-hour period? If you weigh 170 pounds, it's 765 calories. If you weigh 140, it's 630 calories. That's a lot of daily calories your grandparents burned that you don't. To compensate for your office "work," you'd have to run about six miles every day.
Researchers have only recently begun scrutinizing the data around daytime calorie burn. In 2011, Pennington's Timothy Church, M.D., M.P.H., Ph.D., found that U.S. private industry jobs now require 142 fewer calories per day than they did 50 years ago. Church and colleagues, many from Pennington, also determined that this drop in calories out explained 88 percent of the national weight gain over the four-plus decades. In 2013, Edward Archer, Ph.D., then from the University of South Carolina, showed that mothers of young children now burn 225 fewer calories per day than they did in 1965, thanks to labor-saving devices like dishwashers and washing machines that, in turn, have enabled more TV watching.
The most startling revelation appeared last August in The American Journal of Medicine. After analyzing trends in caloric intake, physical activity, and obesity from 1988 to 2010, Uri Ladabaum, M.D., of Stanford University found that Americans 18 and older exhibited increased rates of obesity—particularly belly fat, the most dangerous kind—during a 22-year period when calorie intake "did not change substantially." In fact, over that stretch, calories in actually decreased for some groups: Women ages 18 to 39 reported eating 68 fewer calories per day in 2010 compared with 1988, but the percentage of that population who were overweight increased by more than 20 percent, while those who were obese soared by 56 percent (see table on next page). In his paper, Ladabaum wrote: "Our findings do not support the popular notion that the increase in obesity in the United States can be attributed primarily to an increase over time in the average daily caloric intake of Americans."
Find it hard to believe we're not eating more? Consider another 2014 study, this one in the British Journal of Nutrition. Researchers with the widely respected Framingham Heart Study assessed the same 2,732 individuals over a 17-year period, and found their daily calories in had increased by just 10 calories.
How is this possible? If we're not eating significantly more, why are we getting significantly fatter? Simple. We're not burning enough calories on a daily basis. In fact, a depressing number of Americans do little physical activity at all. In a 2008 study, National Institutes of Health researcher Richard Troiano put accelerometers on a sample of adults in the U.S., and found that only 3.7 percent reached the recommended 150 minutes a week of moderate activity.
In other words, our energy flux is out of whack. Our sedentary lives have pushed our calories out so low that we can't locate the appropriate balance with calories in.
No reputable doctor or metabolism expert would ever suggest that exercise alone can stop obesity. It must be paired with a simple, healthful diet that focuses on a reduction of low-hanging calories—the high-fat and high-sugar ones. It's just that exercise has been undervalued, and diet overexposed. Consider diet's dismal track record. Why are we so intent on repeating past failures?
Just before noon on my last day at Pennington, I manage to squeeze into Tim Church's office. It's not easy. He's been in meetings all morning, keeps getting calls about meetings, and is grumbling about his computer and smartphone, which aren't syncing calendars.
Church figures he has performed more maximal aerobics tests than anyone else—as many as 200,000. After conducting all these tests, he and colleagues correlated the results with a dizzying array of health outcomes, including obesity. The power of exercise never fails to impress him. "It's just so freakin' protective against so many things," he tells me.
Church has less enthusiasm for weight-loss theories. There are said to be a thousand weight-loss programs at loose in the land, and Church has fielded media calls about most of them. This hasn't slowed the rate of calls, or lessened his frustration over the lack of simple answers. "I'm not sure we have a clue about obesity," he tells me.
Of course, I have traveled all the way to Baton Rouge to ask him the same tired questions. I worry that he's going to bark at me, but force myself to carry on. "What do you think is causing so much obesity?" I ask.
Church sighs, takes a long breath, sighs again, and then his face unexpectedly brightens. "I'll tell you the one thing I've learned about diets and weight loss," he says. "Diets are like politics and religion. People believe what they want to believe, and nothing is going to change their minds. The best diet is the one a person happens to believe in, because that's the only one they might stick to."
The same is true for exercise: Do whatever excites you, be it yoga, Cross-Fit, strength training, 5Ks, triathlons, or around-the-block walks with the mutt. If you get tired of one exercise, switch to another. Just don't stop—ever. As Joseph S. Alpert, M.D., editor in chief of the American Journal of Medicine, says: "You only have to exercise on the days that you eat."
Move more at work, too. You've heard it all before, but it bears repeating: Take the stairs, take short walks, stand, stretch, fidget. Sitting is the new smoking, and we all need to cut back—way back. Exercise does so much more than burn calories; it also releases a cascade of hormones, enzymes, and proteins that improve your glucose control, blood pressure, heart health, mood, and more. The key to lifelong weight control is finding the right balance between diet and exercise, with plenty of exercise.
Eight years ago, writer Michael Pollan added pith and insight to the national nutrition debate with his often cited seven-word coda: "Eat food. Not too much. Mostly plants." Short, simple instructions have great power; we remember them, and they move us to action. Whether we admit it or not, we all seek a few maxims to guide our chaotic lives.
Pollan didn't intend it, but he ignited a modest parlor-game competition among other health advocates. Many have mimicked his effort, always trying for fewer words.
Since this is a parlor game, anyone can play. You. Me. Here's my contribution—four words relating to diet, health, weight, and exercise. The words include, importantly I think, a nod to the eternal cycles of Nature.
Food. Feet. Water. Repeat.
* * *
Ready to start? For seven great ways to lose weight, check out this slideshow.
