The growing familiarity of the statistics does little to ease the painful realization of how disturbing they are. About a third of Americans are overweight, and another third are obese—a jump from just 13 percent obese in 1962—and as a nation we are growing fatter all the time. The excess weight has severe consequences. It causes more than 160,000 additional deaths in the U.S. annually and exacts a financial toll: health care for a person who is 70 pounds or more overweight can cost an additional $30,000 over a lifetime. Many other countries, in both the industrial and developing worlds, are seeing similar trends.

At the same time, in a crowded and en­vironmentally stressed world—with global population rising from 6.9 billion today to an estimated 9.3 billion in 2050—humanity is going to need to find sustainable sources of protein and nutrients.

In this edition, two feature articles take on the issues surrounding these very disparate food challenges. Our cover story, “How to Fix the Obesity Crisis,” by David H. Freedman, explains the complex web of factors—social, environmental, genetic and economic—that led us to this situation. Someday science may find a pharmaceutical answer to weight gain. But until then, we have only the currently available solutions that are best supported by research. What they are may surprise you.

Fish farms, as now practiced along coastlines, have had a controversial role in satisfying our hunger for seafood, given their track record of problematic environmental practices. With many wild fisheries collapsing from commercial overharvesting and the continuing difficulties of sustainably raising livestock such as cows, pigs and chickens on land, however,
we need better answers. Could new offshore fish farms—assuming they can function efficiently—be a productive direction to explore? Contributing editor Sarah Simp­son’s report takes a look at that question. See “The Blue Food Revolution.”

Changing topics, I’d like to update you on two items that I mentioned in my letter last issue. We have now introduced an app for the iPhone, called Scientific American Advances; we plan other mobile versions later this year. And by the time you see this issue, our first app for the iPad will be available for download. Called “Origins and Endings,” it tells compelling stories about the cosmos, life and human innovations through feature articles, videos, interactive informational graphics, audio and slide shows from our archives. And as always, we are eager to receive your feedback.