Older adults who are overweight may have a lower risk of dying within 30 days after major elective surgery compared with those with a normal body mass index (BMI), according to a US study published in JAMA Network Open.
While a high BMI is typically linked to increased surgical risks, age-related changes—such as frailty, fat redistribution and height loss—may alter how BMI affects outcomes in older adults.
How was the study conducted?
Researchers analysed data from 414 patients aged 65 and older who underwent major elective surgeries. Patients were grouped by BMI and their outcomes were tracked for 30 days and one year post-surgery.
Findings:
Overweight patients (BMI 25–29.9) had the lowest 30-day mortality rate: just 0.8 per cent. In comparison, 18.8 per cent of patients with normal BMI died within the same period. The underweight group had the highest mortality rate, with 75 per cent dying within a month. Overweight patients also had fewer overall postoperative complications. But those who were morbidly obese (BMI 40 or above) had significantly higher rates of postoperative complications, though not higher death rates.
These results remained consistent even after adjusting for age, frailty and other health conditions like cancer.
Researchers suggest that extra fat and muscle in overweight individuals may provide reserves that help the body recover from surgical stress. In contrast, lower BMI may reflect diminished physiological reserves or undiagnosed illness. "Traditional surgical guidelines often emphasise having a normal BMI before surgery, but our findings suggest that these recommendations may need to be reconsidered for older adults," said the study’s lead author.