Evidence has been piling up for a while that indicates the toll excessive sitting can take on the body: cardiovascular disease, obesity, elevated glucose and insulin production, blood clots, and a shortened lifespan. A new review of the literature on the consequences of sedentary lifestyles has revealed another complication that can result from too much sitting, that of cancer.

The risks do not apply for all types of cancer, but are significantly increased for endometrial and colon cancers. Researchers examined results from 43 studies conducted to test the effects of sitting on overall health, focusing specifically on 70,000 cases of cancer to determine if sitting was a contributing factor. Statistical analyses were done to control for extra factors, helping to ensure that only the interaction between sitting and rates of cancer were considered.

The results were consistent and showed that for colon cancer, those who sat longest each day saw their risk of cancer jump 24 percent. Those who watched the most hours of television raised their risk by 54 percent compared to those who watched the least amount of television.

The increases in risk for endometrial cancer were more pronounced. The longest daily periods of sitting were associated with 32 percent increase in their risk and 66 percent increase in those who watched the most television.

For every two hours a person spent sitting each day, there was an accompanying eight percent risk increase for colon cancer and a 10 percent increase for endometrial cancer. These effects were not offset by periodic exercising combined with excessive sitting.

Researchers believe that the possible cause of these increased risks come from a combination of factors. People who watch television tend to eat more and make fewer healthy food choices. Sitting also encourages high levels of glucose and insulin in the blood, which has been linked to greater risks of colon cancer. These effects can be mitigated by physical activity after meals, but experts say that activity level needs to be present throughout the day, replacing intervals of sitting, in order to lower risks of these types of cancer.