There is compelling evidence that we sit too much − the negative health effects are real and measurable. Sitting is worse for the otherwise inactive but it even affects those who do exercise!

‘Sitting is the new smoking’ has become quite a popular phrase in recent years. The notion is that sitting is a significant and independent health risk factor linked to mortality, obesity, cardiovascular health, diabetes, some cancers (colon, ovarian, endometrial) and poor mental health. The initial evidence for this claim seemed quite compelling and several lay-press as well as advisory-authority publications have been advising that we need to sit less, even if we are otherwise active. Is this sound advice or just a fad? Has more recent research confirmed the initial findings?


About a thousand published studies have looked at the issue and found an association between prolonged sitting and poor health outcomes, although there are complexities (and some conflicting findings). Examples are:

  • The findings vary slightly in different age groups.
  • The type of sitting or sedentary behaviour influences the health impact: TV watching is particularly negative.
  • There are associated risks with certain types of sitting. For example, TV watching includes exposure to unhealthy food advertising and snack-eating as well as being associated with psychosocial problems and lower socio-economic status. These associated risks are difficult if not impossible to exclude or control-for in research.
  • The link to certain cancers such colon, endometrial, and ovarian is present but not strong.
  • Some but not all studies have found that when BMI is controlled-for as a variable, the association with metabolic risk (diabetes) falls away.
  • There is not yet consensus on the precise amount of sitting that should be encouraged or aimed for or set as a limit.
  • Prolonged sitting is worse for those who are inactive (do not exercise) but several studies have also shown that prolonged sitting is associated with poor health outcomes even for those who are active (exercise).

In summary, the body of research is extensive and the results are convincing, even though more research is needed in several areas before full consensus is reached


World authorities have published a variety of recommendations and these continue to evolve over time. A reasonable and practical distillation of these, for adults, is that we should:

  • Be active (non-sweaty or ‘incidental’ activity such as walking) for 30 minutes each day or on most days.
  • Exercise vigorously (sweaty exertion involving being short of breath) for 150 minutes each week.
  • Minimise the amount of time spent sitting.
  • Always seek medical advice before starting any exercise regimen.

Minimising the amount of time you spend sitting is a fairly new addition to the above recommendations and may be the most difficult one to achieve for many office workers who sit as they work. Most authorities do not currently set a specific target, although research suggests that sitting for more than 4–5 hours a day is unhealthy.


Some ways to reduce sitting-time are:

  • Watch less TV – television consumes huge amounts of time that could often be spent more constructively. The associated sitting adds health risk is an additional reason to curtail this habit.
  • Exercise equipment in the TV room – this seemingly ‘odd’ idea really works for many people. Integrating activity into social and family and TV time can really make a difference.
  • Stand-up desks – they can be expensive and they take some getting used to, but standing desks are becoming more popular for good reason.
  • Stand-up meetings – less sitting, more focus, better health, and no one can fall asleep!
  • Break it up – try not to sit for more than 30–45 minutes at a time. A short break or a quick walk will help.


It does seem clear that sitting is unhealthy. More specifically prolonged sitting (probably anything more than 4–5 hours a day), especially while watching TV, and especially (but not only) if you do not exercise. So, please, stand up!

Author: Dr Colin Burns, Health & Wellness Consultant at Sanlam Health