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OBJECTIVES Use a large database design and multivariable analyses to assess the associations between BMI and femur fracture patterns after controlling for other risk factors. DESIGN Retrospective cohort study. SETTING National insurance claims database of patient records from 2010-2018.Patients/Participants: Patients with femur fracture diagnoses were identified. Patients with multiple fractures within one week (poly-trauma patients), patients without a BMI diagnosis code within six months of fracture, and patients with multiple BMI diagnosis codes (implying a substantial change in weight) were excluded. INTERVENTION N/A. MAIN OUTCOME MEASUREMENTS Patients were divided into groups based on fracture location: proximal (OTA 31), shaft (OTA 32), or distal (OTA 33). The distribution of femur fractures was compared across BMI categories. RESULTS A total of 57,042 femur fracture patients were identified: 45,586 proximal fractures, 4,216 shaft fractures, and 7,240 distal fractures. Patients with BMI <29.9 have increased odds (p < 0.0001) of proximal fracture and decreased odds (p < 0.0001) of shaft or distal fractures. Patients with BMI >30.0 have decreased odds (p < 0.0001) of proximal fracture and increased odds (p < 0.0001) of distal fractures. CONCLUSIONS Increasing BMI is associated with a decreased proportion of proximal femur fractures and a corresponding increase in the proportion of shaft and distal fractures. Regression analyses determined that age, gender, osteoporosis, diabetes, and tobacco use are not the cause of this trend. LEVEL OF EVIDENCE Level III. See Instructions for Authors for a complete description of levels of evidence.