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

Authors: Cao, Jay

Submitted to: New York Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2018
Publication Date: 7/31/2018
Citation: Cao, J.J. 2018. Caloric restriction combined with exercise is effective in reducing adiposity and mitigating bone structural deterioration in obese rats. New York Academy of Sciences. https://doi.org/10.1111/nyas.13936.
DOI: https://doi.org/10.1111/nyas.13936

Interpretive Summary: Lifestyle change, such as caloric restriction and/or exercise, to achieve a healthy body weight is a primary and effective strategy for reducing obesity and obesity-related comorbidities and improving quality of life. However, caloric restriction and exercise may have opposite effects on bone health. We studied the effects of weight reduction through caloric restriction and/or exercise on body composition, bone structure and the molecular characteristics of bone metabolism in an obese rat model. We found that caloric restriction was more effective in decreasing adiposity than exercise alone but was detrimental to the bone microstructure. We also found that caloric restriction combined with exercise decreased adiposity and improved bone structure. Our data suggest that weight loss through a combination of exercise and diet restriction may provide optimal benefits for reducing obesity and preserving bone health.

Technical Abstract: Weight reduction through either caloric restriction (CR) or exercise (Ex) is recommended to reduce obesity-related health disorders. However, CR and Ex can have opposite effects on the skeletal system. This study investigated the effects of comparable weight reduction through CR and/or Ex on body composition, bone structure and molecular characteristics of bone metabolism in an obese rat model. We tested the hypothesis that CR combined with Ex is the most effective approach in reducing adiposity while maintaining bone structure in obese rats. Male 6-wk-old Sprague Dawley rats were randomly assigned to six treatments and fed ad libitum a normal-fat (NF, 10% energy as fat) diet for 6 months or an obesogenic high-fat (HF, 45% energy as fat) diet for 3 months. Rats on the HF diet then continued on the HF diet with or without CR or Ex for an additional 3 months. Compared to the HF diet, CR at 8% or 16% (HF+8CR and HF+16CR) or with Ex (HF+Ex+8CR) decreased fat mass and percent adiposity. CR was detrimental to bone microstructure. Compared with the HF group, the HF+8CR group had lower serum tartrate-resistant acid phosphatase (TRAP, a bone resorption marker) and bone volume/total volume (BV/TV) at the distal femur (P < 0.05) and the HF+16CR had lower serum IGF-1, osteocalcin (bone formation marker), TRAP, and BV/TV at both the distal femur and 2nd lumbar vertebrae. HF+Ex+8CR decreased serum TRAP (P < 0.05) compared to the HF group. These data indicate that CR was more effective in decreasing adiposity than Ex alone, but was detrimental to bone structure. CR combined with Ex decreased adiposity and mitigated bone structural deterioration associated with weight reduction.