Daily Exercise Helps Women to Maintain Healthy Weight

While in 2008, US federal guidelines recommended at least 150 minutes per week (7.5 metabolic equivalent [MET] hours per week) of moderate-intensity activity for "substantial health benefits," the amount of physical activity needed to prevent long-term weight gain has remained unclear. I-Min Lee, from Brigham & Women’s Hospital (Massachusetts, USA), and colleagues analyzed data collected on 34,079 women, average age 54 years, enrolled in the Women's Health Study from 1992 to 2007, all of whom were healthy at the study’s start. Over the course of the mean follow-up of 13 years, the women gained a mean of 2.6 kg (5.7 lbs). The team found that those women who exercised the most, at 420 minutes or more a week, gained significantly less weight than those who exercised less than 420 minutes per week.  Further, those who exercised the least gained an additional 0.12 kg over a three-year period (as compared to the most active women), and those who exercised between 150 and 420 minutes per week gained an additional 0.11 kg in 3 years’ time.  The researchers determined that among the women who gained the least weight, the mean activity level was 21.5 metabolic equivalent [MET] hours per week, equivalent to just over 60 minutes a day of moderate-intensity exercise, and conclude that: “Women successful in maintaining normal weight and gaining fewer than 2.3 kg over 13 years averaged approximately 60 minutes a day of moderate-intensity activity throughout the study.”