Many U.S. adults weigh more than they should. Being overweight puts people at risk for poor health and contributes to many common chronic diseases, such as high blood pressure and diabetes. However, little is known about the outcomes of overweight people during serious illnesses requiring treatment in an intensive care unit. Acute lung injury is a condition where the lungs become inflamed and people develop difficulty breathing. People with acute lung injury often need intensive care unit treatment with mechanical ventilation. Mechanical ventilation involves putting a tube down a person's throat and connecting it to a machine that breathes for the patient. Some doctors suspect that people who are overweight have a more difficult time recovering from acute lung injury than patients who are of normal weight.