More exercise, less sitting, to prevent obesity
29th July 2014 – New UK research on reducing obesity suggests you don't just need higher levels of physical activity but also less time spent sitting during your leisure hours.
Physical inactivity and a sedentary lifestyle are both associated with 21st century living. They're also both associated with obesity and chronic conditions such as type 2 diabetes and cardiovascular disease. Studies often consider physical activity and sitting separately so, until now, evidence on their combined effects has been limited.
The authors of the new research say in a statement: "The effectiveness of physical activity for preventing obesity may depend on how much you sit in your leisure time. Both high levels of physical activity and low levels of leisure time sitting may be required to substantially reduce the risk of becoming obese."
The new findings have been published in Diabetologia, the journal of the European Association for the Study of Diabetes.
Joshua Bell and colleagues, Department of Epidemiology and Public Health, University College London (UCL) set out to investigate the combined effects of physical activity and leisure time sitting on, amongst other things, the long-term risk of developing obesity, high blood pressure, high blood glucose and insulin resistance.
The duration of physical activity and of leisure time sitting was assessed by questionnaire between 1997 and 1999 among 3,670 participants from the Whitehall II study of British government employees (73% male; average age 56 years).
Participants reported the frequency and duration of various activities including sports, walking, cycling, home maintenance and gardening. They were also asked how many hours a week they spent sitting at home including watching TV, sewing and desk or chair-based activities such as sitting at a computer.
The researchers found that the lowest odds of becoming obese after 5 years, even when adjusted for things like smoking and alcohol consumption, were observed for individuals reporting both high physical activity and low leisure time sitting.
This result was also observed after 10 years, although the size of the effect was smaller.
Joshua Bell told us by email: "Our results suggest that the protective effects of physical activity against becoming obese may depend upon how much time is spent sitting in leisure, and thus, it may be important for adults to pay more attention to how they use the time in which they are not being purposefully active, or engaging in exercise.
"The mechanisms behind this interaction are unclear, but lower levels of sitting in leisure may serve as a marker for greater engagement in light intensity activity, or for other protective factors, such as a healthier diet."
He says: "Our study was observational, and intervention studies are needed to confirm our findings and test their implications; however, previous research indicates that some activity is certainly better than none, and that there are benefits to breaking up long periods of sitting with light or moderate movements throughout the day."