While reports in the past have linked television viewing with poor health, a new study recently published in the International Journal of Behavioral Nutrition and Physical Activity led by Professor Biddle suggests there is little or no association between sedentary behaviour, such as sitting in front of the television, and obesity in young people.
The study examined 29 published reviews of literature which included more than 450 separate research papers dating back to the 1980s.
Professor Biddle said the analysis of the reviews showed the studies revealed very small associations with how much young people sat, mainly at screens in their free time, and how obese they were.
“After conducting an extensive analysis of the evidence available on this topic, we found the studies were filled with inconsistencies and gaps,” he said.
“While small associations were sometimes found between television viewing and fatness, these were so small as to question their practical value.”
Professor Biddle, who is an expert in active living and public health from the perspective of behaviour change, said the study also found there was no association when wearable technology was used to assess sitting time across the day.
“We also analysed studies that tried to change how much young people sat in front of screens. These also showed very small effects on fatness,” he said.
“Our conclusion was that there is no evidence to suggest that sitting in front a television and other screens causes obesity, and that any claims of it is either premature or misguided.”
Professor Biddle said it was a complex area to study with many factors affecting the results.
“Whether too much sitting is a factor in obesity might also depend on how much physical activity the young people get, what they eat and how much sleep they have,” he said.
“For example, if a 13-year old is highly active through cycling to school and playing sport, watching television in the evening may not be much of a problem for their weight.”
Professor Biddle said although there are many benefits to sitting less and breaking up long bouts of sitting, weight loss does not seem to be one.
“Given that we do many things during the day, the best advice for better health generally is to move more, eat healthy, get adequate sleep and sit less,” he said.
Sedentary behaviour and adiposity in youth: a systematic review of reviews and analysis of causality is published in the International Journal of Behavioral Nutrition and Physical Activity. To access the report, visit https://ijbnpa.biomedcentral.com/articles/10.1186/s12966-017-0497-8