MRI shows sitting for too long can increase fat around organs

Sitting for long periods of time may contribute to greater amounts of fat deposited around one's internal organs, according to a new study published in December issue of Obesity.  

Researchers from the NIHR Leicester Biomedical Research Center in the United Kingdom analyzed cross sectional associations between objectively measured sedentary time (described as little to no activity requiring a high level of energy exertion) and MRI assessed adiposity in a population at risk for developing type 2 diabetes (T2DM), according to the study's main objective.  

"Evidence suggests that the distribution of excess fat is an important determinant of metabolic, cardiovascular, and mortality risk with a predominance of android rather than gynoid being a key contributor (of T2DM)," said the study's lead researcher Joseph Henson from the Diabetes Research Center at the University of Leicester.  

In all, 124 participants—with an average age of 64 years, 65.3 percent of whom were male and had an average BMI of 31.8—were recruited from the Walking Away from Type 2 Diabetes trial. Additionally, participants who posed an even greater risk of developing T2DM were recruited from 10 primary care practices in Leicestershire, U.K., from 2010 to 2011. All participants were unaware of their diabetes risk status before agreeing to participate in the study.  

Sedentary time and moderate to vigorous physical activity were measured with accelerometers worn by the participants at a 12-month follow-up appointment for a period of seven consecutive days. Researchers examined the relationship between sedentary time with liver, visceral, subcutaneous and total abdominal fat through linear regression models provided by MRI scans of each participant.  

Researchers found that an hour of sedentary time was associated with having 1.74 L higher total abdominal fat, 0.62 L higher visceral fat, 1.14 L higher subcutaneous fat and 1.86 percent higher liver fat, according to the study.  

"This study is the first to look at the modifying influence of MVPA on associations between sedentary time and MRI- derived fat distribution," Henson said.  "The finding that the association between sedentary time and visceral fat is stronger in the inactive cohort is intriguing and lends credence to the proposition that physical activity levels may be an important determinant in the accrual of adipose tissue."  

Henson and his colleagues also explained that their findings support evidence in T2DM patients who show disturbance in glucose levels with peripheral insulin resistance, hyperlipidemia and hypertension. Lastly, he identified three strengths particularly notable of the cross-sectional study:  

• It provides evidence of the modifying effect of MVPA on MRI-derived adiposity in a sedentary population with a high risk of T2DM.
• It used gold standard measures in order to quantify regional fat deposition and physical activity levels (all measurements, including MRI scans, were performed by the same team of trained staff following identical standard operating procedure).  
• Participants were recruited from a multiethnic community.