Why Has Obesity Increased?

An Exploratory Seminar on Obesity, sponsored by Academic Ventures, Leads to Strengthened Research
Photo by Jessica ScrantonPhoto by Jessica Scranton
By Pat Harrison

When Barbara B. Kahn RI ’11 received an invitation to participate in an Exploratory Seminar at the Radcliffe Institute in 2004, she was intrigued. The prominent endocrinologist 
at Beth Israel Deaconess Medical Center holds the George R. Minot Professorship of Medicine at Harvard Medical School and speaks at many symposia and conferences—but usually the organizers and speakers are other biomedical researchers, not social scientists.

“Why Has Obesity Increased?” was the title
 of the one-day seminar, and it was led by David Cutler, then dean for the social sciences in Harvard’s Faculty of Arts and Sciences. The Otto Eckstein Professor of Applied Economics in the department of economics and at the Harvard Kennedy School, Cutler also served as the senior health care advisor to Barack Obama’s 2008 presidential campaign.

Even though Cutler invited speakers who are not biomedical researchers, Kahn understood their use of data. “The data related to technological advances about how the obesity epidemic correlates with the use of plastic wrap and freezers and microwave ovens,” she says. In a 2003 working paper, also titled “Why Has Obesity Increased?” for the National Bureau of Economic Research, Cutler and Edward L. Glaeser, another seminar participant, who is now the Fred and Eleanor Glimp Professor of Economics at Harvard, used charts and graphs—pictures of data—to show that Americans have become considerably more obese over the past 25 years. They concluded
 that this trend is largely the result of consuming more meals rather than more calories per meal and correlates with the use of new food technologies and processed food.

In addition to Kahn, Cutler, and Glaeser, 14 scholars from Harvard and its affiliated hospitals participated 
in the obesity seminar, including
 two anthropologists, a psychologist, an epidemiologist, and a historian. Kahn described the experience as “eye-opening” in its multidisciplinary approach.

Every year since 2002, the Radcliffe Institute has sponsored these faculty-led seminars, in which scholars from Harvard and other universities convene 
in small groups for one- to three-day collaborations. The Institute hosted 14 Exploratory Seminars in 2010–2011.

“The seminar got me intrigued with Radcliffe,” Kahn says, “but at that point I wasn’t ready to take the time for a fellowship.” A few years later, though, she wanted to focus on her own multidisciplinary work, so she applied. She proposed a continuation and strengthening of her research on type 2 diabetes with Alan Saghatelian, of Harvard’s Department of Chemistry and Chemical Biology, and with researchers at the Harvard/MIT Broad Institute. She held the Edward, Frances, and Shirley B. Daniels Fellowship at Radcliffe.

Molecular Origins of Obesity and Diabetes

For the past 25 years, Kahn has been working to understand the molecular mechanisms underlying obesity and diabetes. “We know that obesity is a major risk factor for type 2 diabetes,” she says, “but why is that? How does obesity increase the risk for diabetes?” The other priority on her research agenda is to understand the mechanisms by which people become resistant to the action of insulin, the initiating event in developing diabetes. “If we 
can understand how insulin works and how people get resistant to it,” Kahn says, “then we can find new therapeutic approaches to prevent or treat diabetes.”

In collaboration with Saghatelian, Kahn discovered a novel family of lipids (fats) in tissues and blood of mice and humans that had never previously been identified. Her hypothesis is that these lipids may maintain or enhance insulin sensitivity and protect against diabetes, but she hasn’t yet proved that.

During her Radcliffe fellowship, Kahn and her colleagues showed that these lipids are physiologically regulated and identified the class of enzymes that metabolize them. This exciting development could make it possible to maintain high levels of the lipids and thereby decrease diabetes.

Protection Against Obesity and Diabetes


As a longtime physician at Beth Israel— named one of the “Top Doctors in Boston” by Boston magazine—Kahn has an interest in obesity and diabetes that goes beyond basic research. In summary, she says the best way to avoid obesity and diabetes is healthful eating and being physically active. But she knows that it’s often more complicated than that. She tells a story about a patient she treated for many years, who eventually lost weight on Weight Watchers at her workplace, but regained it when the program left the workplace. “I told her, don’t get discouraged about slipping, because every time you get motivated, that’s beneficial. Let’s remotivate and not dwell on the past.”

Kahn is encouraged by new treatments for people who already have type 2 diabetes. “It’s really phenomenal, the new diabetes drugs that have come out in the last decade,” she says. “Some of these agents also decrease appetite. None of them is completely approved for that purpose at the moment, but I think we’ll be seeing more medications that will be effective in some people to reduce appetite.”

The other major wave in clinical 
care of obesity and diabetes is bariatric surgery procedures. “They’re not without side effects, they’re not for everybody, and there are certain criteria to qualify,” Kahn says. “But we’re all very surprised at how effective the surgery is for diabetes.”

Search Year: 
2011