ASPO Abstracts

Analyzing Body Fat in Participants from Project TONE: An Exercise and Diet Intervention to Improve Body Composition in Postmenopausal Women with Normal BMI but Higher Body Fat

Authors: Gao AX, Baum ML, Fares S, Coletta AM, Parker N, Dannenberg AJ, & Basen-Engquist KM

Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2023

Abstract Body:
Purpose: To compare body fat levels in postmenopausal women with normal BMI from Project TONE (NCT04267796), a diet and exercise trial, and the Women's Health Initiative (WHI), in order to explore whether body fat distributions have changed since the 1990s. Methods: Postmenopausal women aged 50-69 with normal BMI were recruited from the employee pool at MD Anderson Cancer Center for a trial of a diet and exercise intervention called Project TONE. As part of screening for Project TONE, we assess body fat levels with a whole body DXA scan. We calculated the quartiles of trunk fat mass and means and confidence intervals for age and BMI of the women screened for the trial. These values were compared with data on body fat in 3,460 postmenopausal WHI participants with normal BMI who were aged 50-79 years from 1993-1998 (Iyengar et al., 2018). Results: Thus far, 35 women have been screened with a DXA scan. For these women, we found that the 25th (8.5 kg) and 50th (10.1 kg) percentiles of trunk fat mass were higher than the 25th (7.4 kg) and 50th (9.4 kg) percentiles in the WHI participants. Additionally, the mean BMI (23.1 [95% CI, 22.4-23.8]) was higher in those screened for Project TONE than in the WHI data (M=22.6). Age was a potential confounder, as those screened for Project TONE were younger (M=57.5 years [95% CI, 55.9-59]) compared with the mean age (63.6 years) from WHI data. Conclusions: The observed higher central adiposity in women screened for Project TONE suggests that body fat levels among postmenopausal women with normal BMI may be higher now (2020s) than before (1990s). Given Iyengar et al.'s finding that postmenopausal women with normal BMI in the highest quartile of trunk fat mass were almost twice as likely to develop breast cancer, lifestyle strategies are needed to promote favorable body composition phenotypes (e.g., lower body fat, adequate muscle mass). Project TONE is underway to determine if exercise and diet changes can improve body composition and reduce biomarkers of breast cancer risk in postmenopausal women with normal BMI.

Keywords: postmenopausal, BMI, body fat, breast cancer, central adiposity