Low-carbohydrate, high-fat diet, and running exercise influence bone parameters in old mice.

We examined the effects and interactions of a low-carbohydrate, high-fat (LCHF) diet and voluntary running exercise on bone in older mice. Male 19-mo-old mice were divided into four groups by diet (control vs. LCHF) and exercise (sedentary vs. voluntary running). The control diet was 55% carbohydrate, 23% protein, and 22% fat, and the LCHF diet was 10% carbohydrate, 33% protein, and 57% fat as percentages of calories. The experiment ended when the mice reached 24 mo old. Statistical analysis was conducted using two-way analysis of variance with diet and exercise. The LCHF diet decreased bone mineral content (BMC), bone mineral density, bone volume fraction, and trabecular number. There was no significant interaction between diet and exercise on many bone parameters. However, there were significant diet and exercise interactions on lumbar BMC and tibial trabecular total tissue volume and average cortical thickness. The LCHF diet attenuated the benefit of running exercise on lumbar BMC and caused running to have a negative effect on tibial trabecular total tissue volume. Our study suggests that the LCHF diet impairs bone mass and some trabecular microstructure and reduces the benefit of exercise on lumbar BMC in old mice. NEW & NOTEWORTHY An LCHF diet is used in treatment and prevention of diseases or improving exercise performance. However, some studies have shown that an LCHF diet diminishes bone in young rodents. Our study demonstrates that an LCHF diet impairs bone mass and some trabecular microstructure in old mice, which are similar to the previous studies using young rodents. Moreover, our study shows that an LCHF diet reduces the benefit of exercise on lumbar BMC in old mice.