People who spend more time sitting or being inactive have a higher risk of developing colorectal cancer and endometrial cancer, even if they exercise regularly.

We analyzed the available evidence and found that people who spend more time sitting or being inactive may have a higher risk of developing colorectal cancer and endometrial cancer, even if they exercise regularly [1]. This pattern was observed in the studies we reviewed, and no studies contradicted this finding. What we’ve found so far suggests that how much time someone spends in sedentary activities—like sitting at a desk, watching TV, or driving—could be connected to cancer risk, independent of whether they also meet physical activity guidelines. This doesn’t mean exercise doesn’t matter; it means that sitting for long periods might add extra risk on top of other lifestyle factors. The evidence doesn’t explain why this link exists, only that it appears consistently in the data we’ve seen. We don’t know if reducing sitting time lowers risk, or if other factors—like diet, weight, or hormone levels—might be involved. The studies we reviewed didn’t test interventions or prove cause and effect. Still, the pattern is clear enough that we can’t ignore it. For now, the evidence we’ve reviewed leans toward the idea that reducing prolonged sitting could be one part of a broader approach to lowering cancer risk, even for people who are otherwise active. If you sit for long hours, try to move a little more often—stand up, walk around, stretch. Small breaks might help, even if you already work out regularly.