A couch potato lifestyle is linked to a significantly greater risk of certain cancers as well as heart disease and diabetes, research has shown.

Every extra two hours spent sitting each day was associated with a 10 per cent increased chance of developing cancer of the womb lining in women, while bowel and lung cancer risk was raised by eight per cent and six per cent respectively.

The effect appeared to be unrelated to how much exercise people took when not sitting. This suggests that even in people who are generally physically active, sitting down for too long can increase cancer risk.

Scientists came to the conclusion after studying pooled data from 43 studies with more than four million participants and almost 70,000 cancer cases. Comparing the highest and lowest levels of sedentary behaviour revealed a statistically significant increased risk for three specific cancers – bowel, endometrial (womb lining) and lung – associated with sitting.

Study authors Daniela Schmid and Michael Leitzmann, from the University of Regensburg in Germany, wrote in the Journal of the National Cancer Institute: “That sedentariness has a detrimental impact on cancer even among physically active persons implies that limiting the time spent sedentary may play an important role in preventing cancer.”

TV viewing time was associated with bowel and endometrial cancers – possibly because watching TV is often accompanied by eating junk food and drinking sweetened beverages.

No association was seen between sedentary behaviour and the risk of breast, ovarian, prostate, stomach, oesophageal (gullet), testicular, kidney and rectal cancers.