Let’s Move (Our Thinking) on Childhood Obesity
Wednesday was the one year anniversary of First Lady Michelle Obama’s “Let’s Move!” initiative to blunt the epidemic of obesity in children. It marks an important fight against a wave of future chronic disease that threatens our national security, our economic growth and the solvency of our health care system.
The obesity epidemic began just about three decades ago. What I reflect upon this anniversary, however, is the much more recent sea change in public health thinking that “Let’s Move!” signifies.
At the core of the White House work to curb obesity — as well as the work of the Centers for Disease Control and the Robert Wood Johnson Foundation — is the now accepted view that changes to our children’s environment, particularly around food and physical activity, have been key factors triggering the epidemic.
These include, for example, saturation marketing of unhealthy foods high in sugars, fats and calories, to the youngest of children — who, of course, lack the cognitive capacity to weigh the short-term pleasure of these snacks against the longer-term harm of diets so dominated by them. And they include school food environments which, while improving, still are not as healthy as they should be. They include community food environments for many children where convenient, walkable full-service supermarkets with fresh produce are a mirage. About 23.5 million urban and rural Americans live in these “food deserts,” without access to healthy foods
If environmental and policy change helped bring about this epidemic, then it makes sense that the CDC and other public health experts now see changes to government policy as one of the most effective ways to make sustainable, healthier changes to our children’s food environment. Change can be driven by policies at the local level, or at the national level like “Let’s Move!” or the upcoming 2012 Farm Bill. Building support for these common sense policies in the health community is a key aim of an initiative I’m working on called Healthy Food Action.
Not everyone accepts the public health perspective. Sarah Palin, for example, has suggested that “Let’s Move!” is tantamount to government interference in our lives. But it’s a core public health principle of the CDC and the world’s leading obesity experts that individual eating behavior doesn’t take place in a vacuum. Rather, unhealthy environmental and policy changes influence and constrain individual behaviors. One cannot walk to school when there are no sidewalks, where it’s unsafe, or where the neighborhood school has been closed. Similarly, school children are unlikely to choose drinking water where water fountains have been dismantled, vending machines only offer soda, or where the soda is cheaper than healthier alternatives.
Let’s Move!” has galvanized moms, doctors, school officials, Wal-Mart and soda companies to start acting as part of a community-wide effort to make our kids’ environments healthier.
Voluntary efforts are great. But so long as public policy supports unhealthy environments, we will make limited progress. Now that we’ve moved our thinking, let’s move public policy.
Brain’s response to sugars may explain obesity
Two very similar sugars — fructose and glucose — cause quite opposite reactions in some regions of the brain, according to a new study. Fructose stimulates brain activity in those regions, while glucose decreases them.
The findings support the idea that an increase in Americans’ fructose consumption over the past decades has helped fuel the nation’s obesity epidemic, the researchers said.
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Although scientists don’t fully understand the link between fructose and behaviors that lead to obesity, the fact that the brain scans show the sugars affect some regions differently supports the idea that such a link exists, said study researcher Dr. Jonathan Purnell, a professor of medicine at Oregon Health & Science University.
The areas of the brain affected by these sugars “have been implicated in our decision-making process about what foods we like and don’t like,” Purnell said.
While fruits and sweet beverages generally contain both sugars, sweetened beverages generally contain a higher ratio of fructose to glucose than other foods.
Your brain on sugar
No one had looked at the human brain before to observe the direct effects of these sugars, Purnell said. The findings will appear in the March issue of the journal Diabetes, Obesity and Metabolism.
The researchers used a functional magnetic resonance imaging (fMRI) scanner to observe the brains of nine people receiving an IV infusion of glucose, fructose or saline solution. The subjects were of normal body weight and had an average age of 29.
Two regions of the brain’s cortex — the orbitofrontal cortex and the cingulate gyrus — were found to react much differently to the two sugars.
“Brain activity in these regions went up with glucose and went down with fructose” from baseline measurements, Purnell said. The magnitudes of the sugars’ effects were equal — brain activity rose in response to glucose by the same extent that it fell in response to fructose.
“That’s a 200 percent difference in brain signaling,” Purnell told MyHealthNewsDaily.
Previous research on animals had shown that another brain region, the hypothalamus, reacted to these two sugars differently. The new study did not find such a difference in the human hypothalamus, Purnell said, but the methods used in the two studies differed, so there may be a reaction difference in people, too, that was not apparent in the brain images.
The study didn’t measure changes in appetite or eating behaviors. Making a direct comparison to soda consumption is difficult, but the amount of sugar given by IV in the study is “certainly much more than you’d get in a can of soda,” Purnell said.
The researchers used an IV instead of asking the study participants to drink sugar solutions because the act of drinking can further affect the brain. Drinking triggers a release of hormones by the intestines, and other changes in the body. To observe the effects of only the sugars, IV transfusions were needed.
What the findings mean
The study does not directly speak to a difference in the way the body processes regular sugar compared with the way it processes high-fructose corn syrup, Purnell said. Table sugar consists of sucrose, and sucrose molecules are basically one glucose molecule and one fructose molecule linked together.
“Other studies have shown, from an epidemiological standpoint, that a marked increase in processed foods, whether they’re sweetened with fructose sweeteners or sucrose, which contains fructose, coincides with weight gain,” he said.
Still other work has shown that among sugars, fructose has unique effects on the body, Purnell said. In a 2009 study reported in the Journal of Clinical Investigation, participants who consumed fructose had a greater increase in belly fat and triglyceride levels than those who consumed glucose.
The new study may explain why those effects were seen, Purnell said. “The question that needs to be answered is: Do these brain changes predict changes in food preference, and in food intake ?”
The answer is likely yes, he said. “I think these signal changes in the brain do represent what we’re seeing, but we need to look at other areas, too. What we’re picking up here is playing a role, but [we] need to get more specific with it, and see how the brain controls food-seeking behavior.”
