Influence of Exercise and Weight Loss on Glucose Tolerance and Bone Mass in Young Growing Animals

Abstract

Childhood obesity has been associated with increased fracture incidence, but the effects of weight loss and exercise on the bone health of children remains unknown. Therefore, this study was designed to determine the effects of exercise and weight loss on bone mass and glucose homeostasis in a young growing animal model of diet‐induced obesity. Six wk old male C57BL/6 mice (n=42) were fed a control diet (CON=10% fat) or high fat diet (HF=60%) for 12 wks. The last 4 wks of the study, mice were further divided into exercise (Ex), no exercise (NoEx), or weight loss regimen (HF→CON). At end of the study, body weight was not significantly reduced in the HF+Ex group. In contrast, the 15% reduction in weight in the HF→CON group resulted in similar body weights to mice on the CON diet. Both the HF+Ex and the HF+NoEx groups experienced an increase (P<0.05) in fasting glucose, but the glucose levels of the HF→CON group were normalized to the CON groups. The HF+Ex and HF→CON groups demonstrated a similar response in their glucose tolerance test. The 4 wk exercise protocol increased whole body and femur bone mineral density (BMD), but the HF→CON mice significantly reduced their spine BMD compared to the non‐exercising groups. These data suggest that in obese animals weight loss without exercise results in a negative effect on spine bone density.Grant Funding Source : Oklahoma Agricultural Experiment Station