PITTSBURGH-Women who exercised 250 to 300 minutes per week-in recommended increments totaling 40 to 60 minutes a day, five days per week-and reduced calorie and fat intake, lost up to 15 percent of their body weight, or about 25 pounds, in about six months and kept the weight off for the remainder of the year, according to a study by University of Pittsburgh Associate Professor John Jakicic published in the Sept. 10 Journal of the American Medical Association (JAMA).
Jakicic, of Pitt's Department of Health, Physical, and Recreation Education (HPRE) in the School of Education, and his colleagues revealed their findings in the JAMA article titled "Effect of Exercise Dose and Intensity on Weight Loss in Overweight, Sedentary Women."
An exercise physiologist who directs Pitt's Physical Activity and Weight Management Research Center, Jakicic coauthored the study with Kara I. Gallagher, the assistant director of the center. Additional researchers were Bess H. Marcus, professor, and Melissa Napolitano, assistant professor, both of the Centers for Behavioral and Preventive Medicine in the Brown Medical School and the Miriam Hospital, Providence, R.I.; and Wei Lang, assistant professor, Department of Public Health Sciences, Wake Forest University,Winston-Salem, N.C.
The researchers found that the 184 women who completed the study successfully achieved significant weight loss and improved cardiorespiratory fitness through the combination of exercise and diet followed during a 12-month period, although no differences were found as a result of different exercise doses and intensities in study participants.
The study involved adult women ranging in age from 21 to 45 years with a baseline body mass index (BMI) of 27 to 40. Prior to starting this study, the participants were classified as sedentary, which was defined as reporting exercising less than three days per week for less than 20 minutes per day over a period of six months.
Participants were instructed to exercise five days a week, with walking encouraged as the primary mode of exercise. They were randomly assigned to one of four groups: vigorous intensity/high duration, moderate intensity/high duration, moderate intensity/moderate duration, or vigorous intensity/moderate duration.
In addition, participants were enrolled in a standard behavioral weight-loss intervention, which was based on social cognitive theory. They were required to attend behavioral group meetings throughout the 12-month period studied. All participants also were instructed to reduce energy intake to between 1200 and 1500 calories per day and restrict dietary fat to 20 to 30 percent of total calories.
Participants in the four groups were assessed at the start, at six months, and again at 12 months. Not only did study participants lose weight, but they also significantly increased cardiorespiratory fitness-compared with their baselines values-at both the six- and 12-month assessments.
The recommendation based on the study's outcomes is that women participate in moderate exercise and progressively increase to 60 minutes at least five days a week and eat a healthy diet to achieve and maintain weight loss and cardiorespiratory fitness for a lifetime.
EDITORS: John Jakicic (pronounced ja-KEE-zick) is available by phone at 412-648-4312 (office), 412-648-8914 (direct), 412-951-0722 (cell), or through Trish White at 412-624-9101.