A high-fat diet can adversely affect bone mechanical properties, but it is unknown how these changes affect bone adaptation. Bone adaptation occurs in response to strain- related mechanisms, and strain in the bone is affected by the size and mechanical properties of the bone. The purpose of this study was to compare the strain during loading in femurs from rats fed a high-fat (HF) or normal control (NC) diet. At 3 weeks of age, male and female Wistar rats were randomly assigned to receive a NC (NC–17% fat;​ N=8 per gender) or HF diet (HF–41% fat;​ N=8 per gender) until termination (39 weeks of age). Right femurs were loaded ex vivo in 3-point bending to physiologic levels and mechanical strain was measured. The mechanical properties of the left femurs were determined by 3-point bend tests to failure. The dietary effects were limited in both genders. Femoral cross-sectional area properties (bone area, moment of inertia), determined from microCT scans, were significantly greater in HF femurs vs. NC for males and females. Elastic modulus was calculated from strain and deformation data and no dietary effects were seen in either gender. At the applied loads, despite significantly larger cross-sectional area properties in the HF femurs, there was no significant difference in strain between HF and NC femurs for either gender. As a comparison, an expected HF femur strain was calculated using the average elastic modulus of the NC femurs and the HF femur cross-sectional properties. A significant difference was found between the expected HF strain and the measured NC strain. Together, these findings suggest that the greater cross-sectional area properties are a compensatory mechanism for deficient material properties in the HF femurs. Adaptive modeling during growth appears to take place to target a predetermined level of strain to preserve bone structural integrity.