Five habits and up to 14 more years
Suppose you counted how many of five habits you have today.
The five are never smoking, a healthy weight, at least 30 minutes a day of moderate or vigorous activity, moderate drinking, and a healthy diet. A healthy weight means a body mass index of 18.5 to 24.9. Moderate drinking means up to about one glass of wine a day for women and two for men. A healthy diet means a diet quality score in the top 40%.
Harvard researchers asked what each count means for life expectancy. They used two long studies of health professionals. The Nurses' Health Study followed 78,865 women from 1980 to 2014. The Health Professionals Follow-up Study followed 44,354 men from 1986 to 2014.
They then applied the results to United States death rates and to the habits of the United States population from national surveys.
Life expectancy at 50, by number of low-risk habits (Harvard study, Circulation, 2018)
| Group | Women | Men |
|---|---|---|
| None of the five habits | 29.0 | 25.5 |
| All five habits | 43.1 | 37.6 |
| Difference | 14.0 (11.8 to 16.2) | 12.2 (10.1 to 14.2) |
| United States average, 2014 | 33.3 | 29.8 |
Ranges in brackets are 95% confidence intervals.
Death risk with all five habits was about a quarter of the risk with none. The ratio was 0.26, with a range of 0.22 to 0.31. For deaths from heart disease the ratio was 0.18. For deaths from cancer it was 0.35.
One habit alone was linked to about two more years in both men and women. Which habit it was did not change that result.
Years free of cancer, heart disease and diabetes also rose. At 50, women with four or five habits could expect 34.4 such years, against 23.7 with none. For men it was 31.1 against 23.5.
Other studies point the same way. A 2017 study used the Health and Retirement Study. People 50 and older who had a normal weight, never smoked and drank in moderation lived about seven years longer on average. A study of 9,945 Korean adults aged 45 and over compared people with risk factors against people with none. Death risk was about 1.9 times higher with one, 2.5 times with two and 3.5 times with three or more. The Korean figures are before adjustment and use a different list of risks.
These are observational studies. They show that people with these habits lived longer, and they cannot show that the habits alone caused it. The Harvard participants were health professionals and may differ from other groups.
Our life expectancy calculator uses the Harvard ratio, and it weakens the effect after 65. Studies of older people find smaller effects. So the gain at 60 is smaller than the gain at 50.
A 60-year-old in the United States, by number of habits (our calculation)
| Habits | Woman, more years | Woman, chance of 90 | Man, more years | Man, chance of 90 |
|---|---|---|---|---|
| 0 | 21.1 | 18% | 18.3 | 12% |
| 1 | 22.8 | 24% | 20.2 | 18% |
| 2 (about average) | 24.4 | 30% | 22.0 | 24% |
| 3 | 25.9 | 37% | 23.8 | 30% |
| 4 | 27.4 | 43% | 25.5 | 37% |
| 5 | 28.8 | 49% | 27.1 | 43% |
The change from none to all five is about 8 to 9 years at 60, against 12 to 14 years at 50 in the Harvard study.
The same count is on the calculator page. You can change it there and watch the chance of reaching 90 change.
Return to the count you made. Whatever it was, the studies suggest each habit was linked to added years.
Which habit was easiest to keep, and what helped? Tell us in the comments. Someone may need the same help.
Sources we read
Harvard Gazette, "5 healthy habits may increase life expectancy by decade or more," 2018. https://news.harvard.edu/gazette/story/2018/04/5-healthy-habits-may-increase-life-expectancy-by-decade-or-more/
Li and others, Impact of healthy lifestyle factors on life expectancies in the US population, Circulation, 2018. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.117.032047
American College of Cardiology, summary of the Circulation study. https://www.acc.org/latest-in-cardiology/journal-scans/2018/05/08/14/40/impact-of-healthy-lifestyle-factors-on-life-expectancies
Li and others, Healthy lifestyle and life expectancy free of cancer, cardiovascular disease, and type 2 diabetes. https://pure.psu.edu/en/publications/healthy-lifestyle-and-life-expectancy-free-of-cancer-cardiovascul/
Harvard Health Publishing, "Healthy lifestyle: 5 keys to a longer life". https://www.health.harvard.edu/blog/healthy-lifestyle-5-keys-to-a-longer-life-2018070514186
Lifestyle risk factors and mortality, Korean Longitudinal Study of Aging. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6747152/
Our life expectancy calculator and World Health Organization 2019 life tables. https://claude.ai/artifact/UgScC4Cit4CGiZZMkP41Wi
Tell us in the comments