Will cassava be Oprah's next favorite thing?

DIET FOOD | Less fat, not exercise key to weight loss

The giant cassava root has an acrid taste and needs to be soaked in water to flush out the cyanide, but the tuber -- popular in Nigeria -- may be just the thing to help Oprah Winfrey lose weight.

Winfrey has pledged to slim down in 2009, and her plans include a 6:15 a.m. workout at the swanky East Bank Club. But a recent study, involving researchers from Loyola University Chicago's Stritch School of Medicine, suggests diet, not exercise, may be the key to shedding pounds.

The study compared a group of African-American women in Chicago with women in rural Nigeria. On average, the Chicago women weighed 57 pounds more than the Nigerian women, even though both groups had about the same amount of daily physical activity.

"On average, what we found is that calories burned in physical activity aren't really associated with weight change -- and certainly clinical studies have supported that," said Loyola nutritionist and associate professor Amy Luke.

Typically, the Nigerian women -- living in rural mud-brick homes -- have low-fat diets that include the staple cassava root, Luke said.

"It's not my favorite food on Earth," Luke said. "It has kind of an acrid taste."

The Chicago women's diets were about 40 percent fat, she said.

Even if Winfrey doesn't slim down at the East Bank Club, the exercise will certainly be good for her heart and help reduce the risk of diabetes, Luke said. "She's not wasting her time at all."