WASHINGTON - It's a question that impacts our physical health, our mental health and health systems throughout the world: What causes us to overeat?
"What's happening in this country is a matter of grave concern," says Walter Willett, chair of the Department of Nutrition at Harvard School of Public Health.
"About two-thirds of Americans are overweight or obese. No matter what, it's not acceptable to be where we are."
Willett was one of four leading health experts who recently spoke at Harvard School of Public Health's forum, "Why We Overeat: The Toxic Food Environment and Obesity."
But the cause for overweight and obesity in the U.S. cannot be limited to one factor. Experts say food engineering, food marketing, the constant availability of food and condition-driven behaviors are the drivers behind overeating and obesity.
It's not genetics
Willet explains that our nation's state of overeating, overweight and obesity "cannot be explained by genes."
That is because obesity rates 50 to 60 years ago were only about one-third of what they are today. Also, other affluent countries, such as Japan and Sweden, don't come close to obesity rates seen in the U.S.
"In some ways, that's an optimistic solution because it means potentially we could change our environment and go back to the obesity rates that are similar to those of Japan and Sweden."
Do we overeat because of our food's ingredients?
According to Dariush Mozaffarian, associate professor in the Division of Cardiovascular Medicine at Brigham and Women's Hospital and Harvard Medical School, diet is the number one driver behind our country's obesity epidemic.
Additionally, the explosion of processed foods since the 80s is a contributor to our current state of overindulgence.
"We used to think, Well, it's just how much you eat, just eat less and you'll be fine, just count calories.' But we've learned it's the quality of what a person eats that's important," Mozaffarian says, who adds that the focus needs to shift to promoting whole, unprocessed food.
"Where we do have a natural sense of sweetness and a natural sense of saltiness, we never had the high levels of sodium and salt that are engineered into our food today," Willet says. "In some ways, we're living in a highly unnatural environment."
Do we overeat because of how food is marketed?
Michael Rich, director of the Center on Media and Child Health at Boston Children's Hospital, says the increase in screen time in recent years has helped to drive a sense of "absentmindedness" that leads to overeating.
According to Rich, young people between the ages of 8 and 18 use media for seven hours and 38 minutes every day. If users eat a snack or a meal during this time, they are distracted by the media, which can cause them to eat more than intended.
"They're not eating for physiologic reasons. They're eating for comfort reasons (they're) disconnected from their body signals," Rich says.
Food's integration into media and entertainment is also a cause for concern with health experts -- especially when it comes to kids. Everything from traditional advertisements, to product placements and advergaming, are being linked to obesity rates.
Rich explains that child viewers "cannot distinguish persuasive intent." In other words, viewers absorb content in an advertisement the same way they recognize content on a show.
"We need to move towards an environment where we are honest with kids and with consumers," Rich says.
Condition-driven behavior and all factors, combined
While some health and policy experts blame obesity on the overabundance of fast food and unhealthy food options, David Kessler, former commissioner of the U.S. Food and Drug Administration and professor in the Department of Pediatrics at the University of California San Francisco, says overeating cannot be blamed on environment and availability, alone.
"I mean, if we put sawdust on every single corner, not everyone would start eating sawdust," Kessler says.
Rather, it is Americans' obsession with food -- and lack of control when it comes to eating -- that causes overeating.
"It's self-administered," he says, adding that certain products in our food, when combined, can propel our obsession with food consumption.
"If you look at the vanilla milkshake and think, What's driving the consumption of that vanilla milkshake? Is it the sweetener? Is it the flavor? Is it the fat?' You find that the most re-enforcing substance is the sweetener, and when you add fat to it, it's synergistic," Kessler says.
But perhaps the true answer lies in how food culture has evolved over the years -- socially, environmentally, behaviorally -- that is to blame.
"Why do we overeat? We took fat, sugar and salt, we put it on every corner, we made it available 24-7, we made it socially acceptable to eat at any time, we made food into entertainment we're living in a carnival. What did we expect to happen?" Kessler says.
Watch the full video of the forum, "Why We Overeat: The Toxic Food Environment and Obesity"
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