(CNN) - Exercise can lengthen your life, even if you're overweight or obese.
Researchers from the National Cancer Institute and Harvard Medical School analyzed studies of more than 630,000 people.
They found that regular, moderate-intensity exercise can boost life expectancy even with an unhealthy BMI, or body mass index.
On the flip side, the doctors say healthy-weight people who don't exercise had about three fewer years of life.
This team of doctors say people should get at least two and a half hours of moderate to vigorous exercise each week