A major study by the Harvard T.H. Chan School of Public Health explored how everyday lifestyle choices impact life expectancy. Using decades of data from two long-term studies—the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS)—researchers tracked over 120,000 people for up to 34 years. That’s a vast amount of insight into how habits shape our health.
They focused on five key areas shown to strongly influence premature death risk: diet, physical activity, weight, smoking, and alcohol use. Here’s how each was defined:
Healthy diet – High in fruits, vegetables, nuts, whole grains, healthy fats, and omega-3s; low in processed meats, sugary drinks, trans fats, and sodium.
Regular physical activity – At least 30 minutes of moderate to vigorous exercise daily.
Healthy weight – A body mass index (BMI) between 18.5 and 24.9.
No smoking – Simply put, never having smoked.
Moderate alcohol – Up to one drink per day for women and two for men.
The findings were striking. People who followed all five healthy habits by age 50 lived, on average, 14 years longer for women and 12 years longer for men compared to those who followed none. Even just one healthy habit could add two years to your life.
These results echo previous research. For instance, a 2017 study found that healthy-weight non-smokers who drank in moderation lived seven years longer. A 2012 meta-analysis of 15 studies involving half a million people concluded that over half of early deaths were linked to unhealthy lifestyle choices.
The Bigger Issue: Prevention vs. Treatment
Despite this overwhelming evidence, the U.S. still spends far more on treating illness than on preventing it. The authors argue that large-scale public health policies—like those used to reduce smoking or eliminate trans fats—are the most effective ways to promote lasting lifestyle change.
But this approach isn’t without opposition. Industries profiting from junk food, sugary drinks, and processed snacks often resist regulation that encourages healthier choices. When public health wins, their profits often take a hit.
Still, the takeaway is clear: small, consistent lifestyle changes can have a massive impact on how long—and how well—we live.
