Caloric restriction combined with exercise is effective in reducing adiposity and mitigating bone structural deterioration in obese rats

Abstract

Weight reduction through caloric restriction (CR) or exercise can have opposite effects on bone. This study investigated the effects of comparable weight reduction through CR and/or exercise on body composition and bone structure in an obese rat model. Male 6-week-old rats were fed either a normal-fat diet for 6 months or a high-fat (HF) diet for 3 months and then started on different CR or exercise regimens for an additional 3 months. Compared to HF conditions, rats given HF diet plus CR at 8% (HF+8CR), HF diet plus CR at 16% (HF+16CR), or HF+8CR plus exercise (HF+Ex+8CR) had lower fat mass. In addition, HF+8CR rats had lower serum tartrate-resistant acid phosphatase and bone volume/total volume at distal femur (P < 0.05), and HF+16CR rats had lower serum insulin growth factor 1, osteocalcin, tartrate-resistant acid phosphatase, and bone volume/total volume at distal femur and 2nd lumbar vertebrae, compared to regimens that included exercise. These data indicate that while CR (e.g., HF+8CR) was detrimental to bone structure, combined with exercise CR (e.g., HF+Ex+8CR) was effective in decreasing adiposity and mitigating bone structural deterioration associated with weight reduction in obese rats.