1 School of Graduate Studies, Concordia University, Montreal, H3G 1N1, Canada.
2 PERFORM Centre, Concordia University, Montreal, H4B 1R6, Canada.
3 Centre de Recherche de L'Institut Universitaire de Gériatrie de Montréal, Montréal, H3W 1W6, Canada.
4 Centre de Recherche de L'Institut de Cardiologie de Montréal, Montréal, H1T 1N6, Canada.
5 Department of Physics, Concordia University, Montreal, H4B 1R6, Canada.
6 Douglas Mental Health University Institute, Montreal, H4H 1R3, Canada.
7 STOP-AD Centre, Montreal Canada, Montreal, H4H 1R3, Canada.
8 Department of Psychiatry, Faculty of Medicine, McGill University, H3A 1Y2, Montreal Canada, Montreal, Canada.
9 Département de Médecine, Université de Montréal, Montreal, H3T 1J4, Canada.
10 PERFORM Centre, Concordia University, Montreal, H4B 1R6, Canada. claudine.gauthier@concordia.ca.
11 Centre de Recherche de L'Institut de Cardiologie de Montréal, Montréal, H1T 1N6, Canada. claudine.gauthier@concordia.ca.
12 Department of Physics, Concordia University, Montreal, H4B 1R6, Canada. claudine.gauthier@concordia.ca.
13 Département de Médecine, Université de Montréal, Montreal, H3T 1J4, Canada. claudine.gauthier@concordia.ca.
14 Department of Physics, Concordia University, Montreal, H3G 1M8, Canada. claudine.gauthier@concordia.ca.

Independently, obesity and physical activity (PA) influence cerebral structure in aging, yet their interaction has not been investigated. We examined sex differences in the relationships among PA, obesity, and cerebral structure in aging with 340 participants who completed magnetic resonance imaging (MRI) acquisition to quantify grey matter volume (GMV) and white matter volume (WMV). Height and weight were measured to calculate body mass index (BMI). A PA questionnaire was used to estimate...