Risks Rise As Your Weight Does: The Heaviest Americans 90,000 women were studied for 5 years. White women with Class 3 obesity (BMI over 40, or, 90- 100 pounds overweight) had a 38 percent greater risk of dying then did women of normal weight (BMI 18.5 – 25). For profoundly obese black women, it’s much worse: 60 percent increased risk. Losing just 20 pounds made a difference to many. Calculate your BMI, free–under Tools, on this page.