Being overweight and/or obese may increase the severity of the H1N1 Virus

(From CDC website on H1N1)

Is obesity considered an underlying medical condition placing people at higher risk of H1N1-related complications?

Obesity is not one of the medical conditions that have previously been recognized to place people at greater risk of serious seasonal flu-related complications; however, obesity has been noted as an underlying medical condition in some hospitalized novel H1N1 patients. In a subset of 268 patients hospitalized with novel H1N1 early on during the outbreak, the body mass index (BMI)* of 227 patients** was calculated. Obesity (defined as a BMI greater than or equal to 30-39.9) was noted in about 15% of these patients and morbid obesity (defined as BMI greater than or equal to 40) was noted in about 8% of these patients. Although the importance of obesity as a contributing factor to novel H1N1 complications is currently unknown, many obese persons have other known underlying diseases that put them at risk for flu complications.

http://www.cdc.gov/H1N1FLU/surveillanceqa.htm