A study published in the British Medical Journal explores time habits and environment in relation to shortening a western lifespan.
Professor David Spiegelhalter, a statistician at the University of Cambridge, looked to find a simple way of communicating the impact of our behaviours on expected length of life. He suggests using the concept of ageing faster or slower, by expressing the daily effect of lifestyle habits as “microlives” (half hours of life expectancy). A half hour of adult life expectancy can be termed a microlife as it is loosely equivalent to one millionth of life after age 35, he explained.
Spiegelhalter’s paper suggests the following behaviours take 30 minutes per day off of a person’s life: Smoking two cigarettes, drinking two extra alcoholic drinks (three a day for women and four a day for men), consuming one portion of red meat, being 11 pounds overweight, watching two hours of television a day. Behaviours that add time to your life include drinking one alcoholic drink a day (adds 30 minutes a day), exercising moderately for 20 minutes a day (adds 1 hour a day), a daily diet of fresh fruits and vegetables (adds 2 hours a day). Being female rather than male also adds 2 hours a day.
Professor Spiegelhalter hopes that this form of communication allows a general, non-academic audience to make rough, but fair comparisons between the sizes of chronic risks, and is based on a metaphor of ‘speed of ageing’, which has been effective in encouraging cessation of smoking. He points to several limitations and stresses that these assessments are very approximate and based on numerous assumptions. However, he says they “bring long term effects into the present and help counter temporal discounting, in which future events are considered of diminishing importance.” In spite of the limitations, he concludes that “a reasonable idea of the comparative absolute risks associated with chronic exposures can be vividly communicated in terms of the speed at which one is living one’s life.”
Source: Spiegelhalter D. Using speed of ageing and “microlives” to communicate the effects of lifetime habits and environment. BMJ. 2012 Dec 14;345:e8223