A recent study by researchers of Johns Hopkins University School of Medicine published in the January issue of The Journal of The American Medical Association suggested that obesity has a marked effect on the life span of both men and women, and that the risk of increased years of life lost(YLL) was greatest at younger ages. The study was based on data from various National Health and Nutrition Examination surveys. The data was used to derive YLL estimates for adults aged 18 to 85 years. Body Mass Index (BMI, [weight in Kg/height in meters squared]) categories were used (i.e., <17; 17 to <18; 18 to <19; 20 to <21; 21 to 45; or greater than 45).
The researchers found that white men aged 20 to 30 years with a severe level of obesity (BMI >45) had a maximum YLL of 13 while it was 8 for white women. For men, this could represent a 22 percent reduction in expected remaining life span. It was found that black men and women above 60 years of age who were overweight or moderately obese did not show an increased YLL while those with severe obesity did indicate increased YLL. However, blacks at younger ages with severe levels of obesity had a maximum YLL of 20 for men and five for women.
The researchers added that among blacks, the pattern of findings suggests that overweight and obesity may not decrease life expectancy until a BMI of approximately 32 to 33 for men and 37 to 38 for women is reached. At these BMI levels, longevity begins to decrease, especially among individuals in the younger age categories. However, the optimal BMI (associated with the least YLL or greatest longevity) was found to be approximately 23 to 25 for whites and 23 to 30 for blacks. It was thus concluded that the recommendations for adults to avoid obesity gained a lot of support in the light of this study.