Researchers have found that having a larger abdomen actually squeezes on your lungs. It was already known that abdominal obesity (waist circumference greater than 35 inches for women and greater than 40 inches for men) was associated with diabetes, hypertension, and cardiovascular disease. Research has shown a positive independent relationship between lung function impairment and abdominal obesity, This association may result from the mechanical effects of abdominal obesity and/or the metabolic effects of the fat tissue. Abdominal obesity may mechanically affect the diaphragm and chest wall compliance with decreased lung volume thereby impairing lung function. This effect was further magnified for those that smoke.