On the joint role of non-Hispanic Black race/ethnicity and weight status in predicting postmenopausal weight gain

Authors: FORD, CHRISTOPHER - Rush University Medical Center; CHANG, SHINE - Md Anderson Cancer Center; WOOD, ALEXIS - Children'S Nutrition Research Center (CNRC); MANSON, JOANN - Brigham & Women'S Hospital; GARCIA, DAVID - University Of Arizona; LAROCHE, HELENA - University Of Missouri; BIRD, CHLOE - Rand Corporation; VITLOINS, MARA - Wake Forest School Of Medicine

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2021
Publication Date: 3/1/2021
Citation: Ford, C.N., Chang, S., Wood, A.C., Manson, J.E., Garcia, D.O., Laroche, H., Bird, C.E., Vitolins, M.Z. 2021. On the joint role of non-Hispanic Black race/ethnicity and weight status in predicting postmenopausal weight gain. PLoS ONE. 16(3):e0247821. https://doi.org/10.1371/journal.pone.0247821.
DOI: https://doi.org/10.1371/journal.pone.0247821

Interpretive Summary: Non-Hispanic Blacks (NHB) in the US have higher rates of obesity than non-Hispanic Whites (NHW). These differences are specially pronounced in women ages 40-59 years of age: 60% percent of NHBs have obesity, compared with just 36% of NHWs. Most women in this age group will undergo menopause, which is often associated with weight gain, a trajectory that is accelerated in NHB women compred to NHW women. Yet, how weight status and race/ethnicity interact to influence the risk of postmenopausal weight gain in NHBs versus NHWs is unclear. The goal of our study was to determine whether greater risk of weight gain in NHB women relative to NHW women is attributable to differences in baseline weight statu alone, or whether race/ethnicity and weight status interact to influence risk of postmenopausal weight gain. After analyzing data from over 83,000 postmenopausal women we found that NHBs were more likely to gain weight than NHWs, and that NHB women who did not have overweight or obesity before the menopause were significantly more likely to gain weight than NHW women without overweight/obesity. This was not true for those with overweight or obesity before the menopause; in these groups NHB and NHW women showed similar rates of gain. Based on this evidence, we concluded that the higher overall risk of postmenopausal weight gain in NHB women, compared to NHW women, was primarily due to difference in risk among those with normal weight, suggesting that interventions to reduce health disparities need to ensure they focus on those without overweight or obesity at baseline, as well as those with these conditions.

Technical Abstract: The objective of the study was to determine how baseline weight status contributes to differences in postmenopausal weight gain among non-Hispanic Blacks (NHBs) and non-Hispanic Whites (NHWs). Data were included from 70,750 NHW and NHB postmenopausal women from the Women’s Health Initiative Observational Study (WHI OS). Body Mass Index (BMI) at baseline was used to classify women as having normal weight, overweight, obese class I, obese class II or obese class III. Cox proportional hazards was used to estimate the hazard of a 10% or more increase in weight from baseline. In both crude and adjusted models, NHBs were more likely to experience =10% weight gain than NHWs within the same category of baseline weight status. Moreover, NHBs who were normal weight at baseline were most likely to experience >=10% weight gain in both crude and adjusted models. Age-stratified results were consistent with overall findings. In all age categories, NHBs who were normal weight at baseline were most likely to experience >=10% weight gain. Based on the results of adjusted models, the joint influence of NHB race/ethnicity and weight status on risk of postmenopausal weight gain was both sub-additive and sub-multiplicative. NHBs are more likely to experience postmenopausal weight gain than NHWs, and the disparity in risk is most pronounced among those who are normal weight at baseline. To address the disparity in postmenopausal obesity, future studies should focus on identifying and modifying factors that promote weight gain among normal weight NHBs.