And now yet another study, this one in the July 2007 Economic Inquiry, says that social factors influence body weight. This study doesn’t say friends make friends fat, but says that the average body weight in a population has a “social multiplier” effect. This, they say, in conjunction with low food prices, encourages weight gain. Read what Dr. David Katz at Yale has to say about obesity “contagion.” He says: “There was virtually no obesity 100 years ago, but I’m pretty sure people did have friends back then. What they did not have was cars, suburban sprawl, fast food, and video games. Human nature and relationships are not the root cause of epidemic obesity; the obesigenic modern environment is.” Indeed.