Study fails to find strong link between sitting and weight gain

Sitting is bad for you, but it is unlikely to make you fat, a University of Otago study has found.

Lead author Dr Meredith Peddie, of the Department of Human Nutrition, says it is known that sedentary behaviour is linked with increased risk of morbidity and mortality from diabetes and cardiovascular disease.

However, there have always been questions around whether this is just because sitting for long periods is making you gain weight.

A team of researchers conducted a systematic review and meta-analysis of 23 international studies which evaluated the link between sedentary behaviour in adults, body weight and obesity.

Because some people who sit for long periods are less physically active and participation in physical activity can also affect weight, all the included studies had to adjust for, or account for levels of physical activity.

The results, published in Sports Medicine, reveal "small, inconsistent and non-significant'' associations between sedentary behaviours such as occupational sitting, or TV viewing and weight gain, or risk of obesity in adults.

For example, over a five year follow-up period, each one hour increase in sedentary behaviour was associated with a "basically negligible'' 0.02mm increase in waist circumference.

"The results might seem counter-intuitive as we know that standing instead of sitting does increase energy expenditure slightly, and replacing sitting with moving further increases energy expenditure – but either these changes aren't large enough to meaningfully impact weight in the long term, or people who move around more are pretty good at compensating for the extra movement by increasing their energy intake,'' she says.

Dr Peddie, who is supported by the National Heart Foundation, points out that the results of this study should not mean people think it is acceptable to give up the standing desk, or get stuck into a binge-watching session on Netflix.

"The results show is that the harmful effects of too much sitting is probably not caused by weight gain.

"However, our intervention studies clearly show that sitting for long periods increases blood sugar and triglyceride levels. The current physical activity guidelines to sit less and move more still apply,'' she says.