Even people with a body mass index of less than 23 can develop NAFLD if their lifestyle is largely sedentary.
Sedentary behavior means that you are in effect "at rest" - you are doing so little that there is no increase in energy burn above "resting level."
The 2008 Physical Activity Guidelines for Americans recommend that adults clock up about 2.5 hours of moderate-to-vigorous physical activity per week. However, the National Health and Nutrition Examination Survey (NHANES) notes that adults are sedentary for an average of 55% of their day.Published in the Journal of Hepatology, the new study looked at the relationship between sitting time and physical activity and nonalcoholic fatty liver disease (NAFLD) in more than 140,000 middle-aged Korean men and women.
Physical activity and sitting times were established from a version of the International Physical Activity Questionnaire Short Form, while ultrasound was used to establish the presence of fatty liver.
'Our chairs are slowly but surely killing us'
Of the study participants, nearly 35% had NAFLD. Both sitting for long periods and less physical activity were independently associated with NAFLD. Of particular note, these same observations were made in people with a normal body weight, defined as a body mass index (BMI) of less than 23.
"Our findings suggest that both increasing participation in physical activity and reducing sitting time may be independently important in reducing the risk of NAFLD, and underlines the importance of reducing time spent sitting in addition to promoting physical activity," says study co-author Dr. Yoosoo Chang, PhD, of the Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine in South Korea.
Michael I. Trenell, PhD, professor of the Metabolism & Lifestyle Medicine at Newcastle University in the UK, adds:
"The message is clear, our chairs are slowly but surely killing us. Our body is designed to move and it is not surprising that sedentary behavior, characterized by low muscle activity, has a direct impact on physiology.
With a dearth of approved drug therapies for NAFLD, lifestyle changes remain the cornerstone of clinical care. The challenge for us now is to 'stand up' and move for NAFLD, both physically and metaphorically."
Earlier this year, Medical News Today reported that a 2-minute walk every hour may reduce the hazard of prolonged sitting.