“Sitting is as dangerous as smoking.”
Moderate confidence. Prolonged sitting is associated with higher mortality, especially among people with little moderate-to-vigorous activity. But quantitative comparisons show smoking carries a far larger mortality risk, so the two exposures are not equivalent.
Sitting is not as dangerous as smoking. High sitting time is associated with worse health outcomes, but the mortality risk increase reported for sitting is much smaller than for smoking. Regular physical activity substantially reduces the sitting-related association.
Sitting time and insufficient exercise overlap but are not identical. The practical goal is both to meet activity guidelines and to avoid letting long sedentary periods dominate the day.
Safety note: Standing is not automatically better for everyone and prolonged standing can aggravate pain, swelling or balance problems. Use a mix of positions and movement that is safe for you.
Talk to a healthcare professional if: Ask for adapted movement advice if disability, dizziness, pain, swelling or fall risk makes frequent standing or walking difficult.
You do not need to fear a chair. If you sit for work or mobility reasons, focus on the movement you can add across the day and on regular structured activity rather than treating sitting like tobacco exposure.
Break up long sitting periods when practical with standing, walking or light activity, and work toward the weekly aerobic and strength guidelines. There is no single proven minute-by-minute break schedule for everyone.