A new Influenza and Other Respiratory Viruses study found that adults who are underweight or morbidly obese have an elevated risk of being hospitalized with influenza-like illness due to the flu virus or other respiratory viruses.

The observational study included 4,778 hospitalized and outpatient patients with influenza-like illness in six hospitals in Mexico.

The risk followed a ”U“ shaped curve, where individuals at both extremes were more likely to develop severe influenza-like illness when compared with individuals with normal weight. The findings indicate that clinicians should keep a patient’s body mass index in mind when evaluating risk of developing severe influenza-like illness and deciding on a course of treatment.