A free nationwide health program called "Choose to Move" involved more than 230thousand women. Most who finished significantly improved their diets and activity levels. There is one catch. Nearly 20-thousand may have dropped out. The results, which will be reported tin tomorrow's Archives of Internal Medicine, show how hard it is to get people to stick with healthy lifestyle changes. Researchers who studied the program's 1999 phase, when 23-thousand, one-hundred and seventhy-one women signed up, call it a success. They say getting 37-hundred, seventy-five people to complete it was no small fast. The ongoing American Heart Association program, started in 1998, involves ordering a free handbook with tips on how to gradually incorporated better nutrition and 30 minutes of exercise into daily life over a 12-week period. Participants are asked to send in progress-report cards during the program and at the end. Lead researcher Dyann Matson Koffman of the Atlanta-based Centers for Disease Control and Prevention said, "reached lots of women who made improvements in their physical activity and their diet." Still , researchers acknowledge the program's limitations. The program targets women aged 25 and older and is designed to fight the nation's high rates of heart disease, obesity and inactivity are contributing factors.