CHICAGO -- Eating less fat late in life failed to lower the risk of cancer and heart disease among older women, disappointing news for those who expected greater benefits from a healthy diet.

Even so, scientists say the results from the government study of 48,835 women don't mean dieters should just throw up their hands and eat cake.

Researchers suggested that the women in the long-running study _ with an average age of 62 _ may have started their healthy eating too late. They also didn't reduce fats as much as the diet demanded, and most remained overweight, a major risk factor for cancer and heart problems.

"These results do not suggest that people have carte blanche to eat fatty foods without health problems," said Dr. JoAnn Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital, a co-author of the study and respected nutrition authority.

Read more about study findings related to the low fat diet at http://www.washingtonpost.com.