What’s considered a normal weight for adults is often based on a measurement known as body mass index (BMI), which assesses weight relative to height. The found that men with a normal BMI but central obesity, the clinical term for belly fat, had twice the mortality risk of men who were overweight or obese according to BMI. Normal weight women with belly fat, meanwhile, had a 32 percent higher mortality risk than obese women without excess pounds around the middle.