Physical activity patterns and prevention of weight gain in premenopausal women

Studies of the association between physical activity (PA) and weight maintenance have been inconsistent.

We prospectively examined the association between PA patterns and prevention of weight gain among 46 754 healthy premenopausal women, aged 25-43 years in 1989. Participants reported their PA and weight in 1989 and 1997. The primary outcome was gaining >5% of baseline weight by 1997 (62% of the population).

Compared with women who maintained <30 min d(-1) of total discretionary activity over 8 years, women were less likely to gain weight if they sustained 30+ min d(-1) (odds ratio (OR)=0.68, 95% confidence interval (CI) 0.64-0.73) or increased to 30+ min d(-1) in 1997 (OR=0.64, 95%CI=0.60-0.68). Among women whose only reported activity was walking, risk of gaining weight was lower in those who sustained 30+ min d(-1) over 8 years (OR=0.66, 95%CI=0.49-0.91), and brisk walking pace independently predicted less weight gain. For a 30 min d(-1) increase between 1989 and 1997, jogging/running was associated with less weight gain than brisk walking or other activities. Greater duration of PA was associated with progressively less weight gain, but even an 11-20 min d(-1) increase was beneficial; the benefits appeared stronger among those who were initially overweight. Sedentary behavior independently predicted weight gain.

Sustained PA for at least 30 min d(-1), particularly if more intense, is associated with a reduction in long-term weight gain, and greater duration is associated with less weight gain. Sedentary women of any baseline weight who increase their PA will benefit, but overweight women appear to benefit the most.