The investigation, conducted by economists at the University of California, Berkeley and Columbia University, followed a large population of schoolchildren over almost a decade. The data they collected were so detailed that researchers were able to observe changes in the years before and after new fast-food stores opened near schools. Their conclusion: rates of obesity in ninth graders were 5 percent higher in schools within one-tenth of a mile of a a pizza or burger joint, compared to students at schools farther away from temptation.

Not surprisingly, the National Restaurant Association attacked the findings, calling them “slapdash.” But economist Enrico Moretti, one of the papers’ authors, defended the study’s conclusions. “We’re quite confident that these are credible and unbiased estimates of the causal effect of fast food on obesity for the group we focused on,” he told The New York Times.

In a related part of the study, the scientists analyzed data from millions of women who gave birth over the past 15 years in New Jersey, Michigan, and Texas. Those who lived within a half-mile of a fast-food restaurant were more likely to gain more than 44 pounds during pregnancy, the data showed.

Obesity researchers were quick to say the findings support zoning law restrictions on fast-food restaurants near schools. Good luck. Our recommendatons: spend more time at school teaching kids about healthy food choices and the lifelong dangers of getting fat. Make more healthy food choices available at schools. And increase the number of after-school physical activities.

© 2009 PDQhealth

The latest findings come from a study of 17 obese men and women conducted at the Monell Chemical Senses Center in Philadephia. The volunteers were fed meals on two separate occasions. The menus were identical except that the beverages were sweetened with glucose at one meal and fructose at another. Testing the participants’ blood after the meals, researchers found that the total amount of triglycerides over the next 24 hours was almost 200 percent higher after consuming fructose-sweetened beverages.

Here’s why that’s cause for concern. Triglycerides are tiny fat particles transported in the blood. Although triglycerides are essential to health, abnormally high levels of these particles are strongly linked to artherosclerosis and heart disease. “Increased triglycerides after a meal are known predictors of cardiovascular disease,” explained metabolic physiologist Karen L. Teff, PhD, who led the study. “Our findings show that fructose-sweetened beverages raise triglceride levels in obese people, who already are at risk for metabolic disorders such as cardiovascular disease and diabetes.”

The effect was particularly pronounced in volunteers who were insulin resistant, an early warning sign of diabetes risk, and in those whose triglyceride levels were already high. Unfortunately, that profile describes millions of Americans today: overweight or obese, with elevated triglycerides and insulin resistance.

The new study comes hard on the heels of a nationwide survey showing that fructose consumption is soaring. Analyzing data from 21,483 children and adults around the country, researchers pegged the average daily intake of fructose at almost 55 grams, up from 37 grams in a survey conducted in the late 1970s. Over 10 percent of Americans’ daily calories come from fructose, the analysis showed. Not surprisingly, perhaps, adolescents consumed the most, a whopping 73 grams a day. One in four adolescents consumed at least 15 percent of their calories from fructose. The biggest source: fructose sweetened beverages.

© 2009 PDQhealth

Every time Dr. James H. Fowler and his colleague Dr. Nicholas A. Christakis publish a research paper, they trigger a media blitz. They grabbed headlines recently with news that obesity can spread through a network of friends almost like the common cold. If your friend—or a friend of that friend—puts on weight, you’re more likely to get chubby. If your friends and their friends are thin, odds are you will be, too. Their latest study, published in the British Medical Journal this month, shows that happiness spreads through extended social networks, as well.

First, what exactly is social network research?

For years scientists have studied how individuals make decisions. Social network research tries to elevate that up to look at the complex ways in which people interact. We’re not Robinson Crusoes, after all, living on desert islands. We’re part of complex societies, and those societies help define who we are. We’re looking at how behaviors and now emotions move through social networks.

How do you put something as complex as a social network under a microscope?

We were lucky to discover that other researchers had done some of the work for us. Since the late 1940s, scientists have been studying heart disease across generations as part of the Framingham Heart Study. As part of that study, to ensure that they’d be able to keep in touch with people, they asked participants to identify a close friend who would know how to contact them in two to four years. (It worked, by the way. Only ten people have been lost to follow up in that study, which includes more than 5,000 volunteers.) Because the study drew on people in a fairly limited geographic area, many of the friends were also participants in the Framingham study, so we had detailed information about friends of friends. The Framingham study gathered up all this great information about the social network of participants. It was the perfect study for us to do our work.

Why did you decide to look at happiness?

We’ve previously studied obesity and smoking. Those are both behaviors, of course. Both turn out to spread through social networks. So we were interested in looking to see if emotions also spread through networks. If your friends and even friends of friends are happy, is that likely to make you happy?

How did you define happiness?

We used conventional measures developed by psychologists, from a survey questionnaire that the Framingham study researchers used. Volunteers were asked how often they experience certain feelings during the previous week. Four of the items addressed happiness. “I felt hopeful about the future.” “I was happy.” “I enjoyed life.” “I felt that I was just as good as other people.” It turns out that the core disposition of happiness is quite stable over time.

And what did you discover about happiness?

We found distinct clusters of happy and unhappy people in the social network. Part of that could be explained by happy people choosing happy people as their friends. But we also found that people who are surrounded by many happy people are more likely to become happy in the future. When someone in the network became happy, friends and friends of friends were likely to become happy. It’s kind of a domino effect. Geography made a difference. People had to live within about a mile of one another to exert an influence. We think that may suggest that frequency of contact is important. It’s a lot like catching the flu. The closer your contact, the more likely you are to catch it. The same with happiness.

How far does the happy bug spread?

Surprisingly far, actually. A person is 15 percent more likely to be happy if a close contact is happy. For a friend of a friend, there’s a 9.8 percent likelihood, and for a friend of a friend of a friend the likelihood is still 5.6 percent. So we traced the effect out to three degrees of separation.

So even strangers can affect how happy people feel?

That’s right. The fascinating thing is that we found virtually the same thing for obesity and smoking. The effect goes to three degrees of separation.  In fact we’re beginning to formulate the three degrees rule.

Why three?

Our theory is that it’s a little like dropping a stone into a still pond. If you drop one stone, you’ll see waves going out across the entire pond. But if you drop several stones at the same time, the competing waves will cancel themselves out at a certain point before they reach the shore. Within an individual’s social network, there are happy and unhappy people, like those several stones. So the effect cancels itself out at three degrees of separation.

What about unhappiness? Does it also spread?

We looked at that, too. In fact, I had a bet with my co-author, Nicholas Christakis, at Harvard Medical School. He was convinced that unhappiness would spread more efficiently. His idea was that unhappiness is like fear, and for evolutionary reasons it’s a matter of survival that if someone is afraid, people around them become afraid. I put my money on happiness. I won that bet. Unhappiness does spread, our results showed, but happiness spreads more effectively. I think the reason it that happiness and positive emotions like trust are required for human beings to cooperate—to hunt large game when we were hunter-gatherers, for instance, and to build complex cities today.

What do you plan to study next?

Actually, the paper on happiness is the third of six papers we plan to publish. So we’ve looked at obesity and smoking, and now happiness. We have papers coming out in the next few months on loneliness and depression and how they spread through social networks. We’re also looking at the dynamic spread of alcoholism through social networks.

In a way, your latest findings are very reassuring, aren’t they?

I think so. They remind us that we’re all connected, in ways more complex than we sometimes think. The findings have certainly changed the way I live my life. Now I understand that my mood, my emotional state, can affect people I’ve never even met. Not just my son but my son’s friend and his friend. Not just my wife but her mother and her mother’s friends. Every day now on the way home I listen to one of my favorite songs to put myself in a good mood. I want my happiness to have a ripple effect.

Photo: Kent Horner

Eight years ago our household got rid of television. It was easy. The cable guy came out, flipped a switch, and the screen went fuzzy.

We’ve never been happier.

Instead of staring at Friends and Seinfeld episodes we’d seen a dozen times, we got into making dinner, trying out new recipes. We read aloud. Instead of channel surfing, we started going out for walks through the neighborhood. We took up old hobbies.

It’s hard to mention that you don’t have television without seeming a little self-righteous. People immediately get defensive. Oh, we have television, but we hardly ever watch it, they say. Or: We only watch PBS.

We mention it simply because a study has just been published looking at television and personal happiness. Or unhappiness, to be more accurate.

In an analysis of data gathered from nearly 30,000 adults, researchers at the University of Maryland found that people who describe themselves as unhappy watch 20 percent more television than those who say they’re happy.

The survey found that self-described happy people, in addition to watching less TV, were more socially active, read more newspapers, and attended more religious services. They also voted more often.

Wierdly enough, TV junkies reported being happy with television. As John P. Robinson, one of the authors of the study, explained, “What viewers seem to be saying is that, ‘While TV in general is a waste of time and not particularly enjoyable, the shows I saw tonight were pretty good.’”

As the researchers point out, it’s easy to watch TV. You don’t have to get dressed up and drive anywhere. Hell, you don’t even have to get up off the sofa. It’s a great way to kill time, and unhappy people, the survey showed, have time to kill. More than half said they had unwanted extra time on their hands, compared to fewer than one in five happy people.

Something else about heavy television watchers has emerged from other studies: they tend to weigh more than infrequent viewers. In a 2008 Canadian study, one quarter of people who watched 21 hours of TV or more a week were obese, compared to only about 12 percent of those who watched five hours or less.

It’s impossible to say, from the latest study, whether watching television makes people unhappy or whether unhappy people tend to watch TV. It is clear, though, that watching a lot of television tends to make people fat. And that probably doesn’t make anyone happy.

The solution, of course, is simple. Turn it off.

Get rid of it if you have to.

You could find yourself feeling a lot happier.

And maybe a few pounds lighter.