Obesity and knee osteoarthritis are among the most frequent chronic conditions in older Americans, with both conditions projected to steadily rise in the coming years. Elena Losina, from Brigham and Women’s Hospital (Massachusetts, USA), and colleagues utilized a mathematical simulation model to assemble national data on the occurrence of knee osteoarthritis, obesity, and other important medical conditions such as coronary heart disease, diabetes, cancer and chronic lung disease. The team’s analysis found that Americans over the age of 50 will together lose the equivalent of 86 million healthy years of life.   Observing that: “The number of quality-adjusted life-years lost owing to knee osteoarthritis and obesity seems to be substantial,” the researchers urge that: “Reducing mean body mass index to the levels observed a decade ago in this population would yield substantial health benefits.”