Effect of exercise duration and intensity on weight loss in overweight, sedentary women: a randomized trial.
BACKGROUND
A higher duration and intensity of exercise may improve long-term weight loss.


OBJECTIVE
To compare the effects of different durations and intensities of exercise on 12-month weight loss and cardiorespiratory fitness.


METHODS
Randomized trial conducted from January 2000 through December 2001 involving 201 sedentary women (mean [SD] age, 37.0 [5.7] years; mean [SD] body mass index, 32.6 [4.2]) in a university-based weight control program.


METHODS
Participants were randomly assigned to 1 of 4 exercise groups (vigorous intensity/high duration; moderate intensity/high duration; moderate intensity/moderate duration; or vigorous intensity/moderate duration) based on estimated energy expenditure (1000 kcal/wk vs 2000 kcal/wk) and exercise intensity (moderate vs vigorous). All women were instructed to reduce intake of energy to between 1200 and 1500 kcal/d and dietary fat to between 20% and 30% of total energy intake.


METHODS
Body weight, cardiorespiratory fitness, and exercise participation.


RESULTS
After exclusions, 184 of 196 randomized participants completed 12 months of treatment (94%). In intention-to-treat analysis, mean (SD) weight loss following 12 months of treatment was statistically significant (P <.001) in all exercise groups (vigorous intensity/high duration = 8.9 [7.3] kg; moderate intensity/high duration = 8.2 [7.6] kg; moderate intensity/moderate duration = 6.3 [5.6] kg; vigorous intensity/moderate duration = 7.0 [6.4] kg), with no significant difference between groups. Mean (SD) cardiorespiratory fitness levels also increased significantly (P =.04) in all groups (vigorous intensity/high duration = 22.0% [19.9%]; moderate intensity/high duration = 14.9% [18.6%]; moderate intensity/moderate duration = 13.5% [16.9%]; vigorous intensity/moderate duration = 18.9% [16.9%]), with no difference between groups. Post hoc analysis revealed that percentage weight loss at 12 months was associated with the level of physical activity performed at 6 and 12 months. Women reporting less than 150 min/wk had a mean (SD) weight loss of 4.7% [6.0%]; inconsistent (other) pattern of physical activity, 7.0% [6.9%]; 150 min/wk or more, 9.5% [7.9%]; and 200 min/wk or more of exercise, 13.6% [7.8%].


CONCLUSIONS
Significant weight loss and improved cardiorespiratory fitness were achieved through the combination of exercise and diet during 12 months, although no differences were found based on different exercise durations and intensities in this group of sedentary, overweight women.
Jakicic
John M
JM
University of Pittsburgh, Physical Activity and Weight Management Research Center, Pittsburgh, PA 15261, USA. jjakicic@pitt.edu
Marcus
Bess H
BH
Gallagher
Kara I
KI
Napolitano
Melissa
M
Lang
Wei
W
D000328:Adult; D004038:Diet, Reducing; D015444:Exercise; D005260:Female; D006801:Humans; D009765:Obesity / Q000628:therapy*; D012146:Rest; D013997:Time Factors; D015431:Weight Loss