Watching Substantial Amounts of TV Increases the Risk of Obesity

​– It could be that an overweight person starts to sit more because of the weight, but according to our study the weight gain is caused by extensive sitting, not the other way around, says Doctor and Researcher Harri Helajärvi.

The research is part of the national Cardiovascular Risk in Young Finns Study administered by the University of Turku.

The researchers studied the effect of the amount of time spent watching TV on the increase in the body mass index and waistline during the ten-year follow-up (2001–2011). The causality of sitting and obesity was researched with a longitudinal follow-up study and with modern mathematical methods.

At the end of the follow-up study, the participants (761 women and 626 men) were 33–50 years old. The daily amount of TV watching was canvassed with a survey.

Extensive Sitting Increases Weight Gain despite the Traditional Risk Factors

According to the research, the time spent watching TV increases the body mass index and waistline despite factors such as age, gender, amount of exercise during free time, smoking and energy intake.

–The study showed that the increase in the body mass index and waistline was at least double for those who watched three hours or more television each night compared with those who watched TV for an hour, says Helajärvi.

For the first time, the research studied the causal relationship of TV watching and obesity with a longitudinal study by applying mathematical methods. Most of the earlier studies done on the effects of sitting have been so-called cross studies and the methods used in this research weren’t applied.

The research was published in the international PLoS ONE medical journal.

Text: Erja Hyytiäinen
Photo: Keirsten Marie
Translation: Mari Ratia