Former Chief of American Heart Association Describes Role of Enzyme in Weight Gain and Loss, Apr 13, 2007, Harvard Public Health NOW

Robert Eckel

Prevention is the answer to many health problems, and obesity is no exception. "Let the scale say five years from now what it says today," said Robert Eckel, immediate past president of the American Heart Association and professor at the University of Colorado at Denver and Health Sciences Center. Eckel discussed how the body changes after becoming obese and also after subsequent weight loss during the annual Stare-Hegsted Lecture sponsored by the Department of Nutrition. The event was held on April 5 in Kresge G-3.

For more than 30 years, Eckel has focused on the role of an enzyme called lipoprotein lipase (LPL) in fat maintenance. Eckel's studies have investigated the role of LPL in tissues, including adipose tissue and skeletal muscle. His results indicate that too much LPL in muscle decreases insulin sensitivity and prevents weight gain on a high fat diet. "Insulin resistance may be a mechanism to limit fatness," Eckel said.

LPL also changes feeding behavior. Mice that have been genetically engineered to have elevated levels of LPL in skeletal muscle do not eat more when exposed to cold temperatures. In contrast, control mice with normal LPL levels increase their food intake when they are in the cold. The results indicate that LPL in the skeletal muscle of mice alters behavioral responses in response to cold and perhaps other stresses.

Eckel framed his findings within the perspective of the availability of food across history. "People who were heavier outlived people who were leaner," he said, listing examples from the World Wars, the Irish famine, and other historical episodes during which a fatter state was a life-sustaining state. "We now live much longer and this protective advantage is no longer true," he added.

D. Mark Hegsted (right), one of the lecture's namesakes, attended on April 5

In America's food-rich society bodies continue to behave as though hunger is imminent, a physiological strategy that Eckel described as the body's defense of fat mass.

"Prevention of weight gain should be the message," Eckel summarized. He added that someday there will be drugs to treat obesity, "But there will likely be multiple drugs with different targets." Eckel also said that while decreased food intake is the key to losing weight, exercise is the key to maintaining the weight loss.

The Stare-Hegsted Lecture is named after Fredrick Stare, the founding chair of the HSPH Department of Nutrition, and HSPH professor emeritus D. Mark Hegsted, who attended the lecture.

—MM