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.
Keywords: bone structure; caloric restriction; exercise; high-fat diet; obesity.
Published 2018. This article is a U.S. Government work and is in the public domain in the USA.