A well-balanced diet combined or not with exercise induces fat mass loss without any decrease of bone mass despite...

Area of Science:

• Bone Metabolism and Obesity Research
• Nutritional Science and Exercise Physiology
• Animal Models in Biomedical Research

Background:

• Obesity management often involves diet and exercise, but weight loss can accelerate bone loss.
• Exercise generally benefits bone health, presenting a complex interplay with weight reduction strategies.
• Understanding the specific effects of dietary interventions and exercise on bone in obesity is crucial.

Purpose of the Study:

• To investigate the impact of a well-balanced isoenergetic reducing diet (WBR) combined with exercise on bone tissue in diet-induced obese rats.
• To differentiate the effects of diet, exercise, and their combination on bone mass, micro-architecture, and resorption markers.
• To assess the efficacy of a WBR diet and exercise in mitigating negative bone changes associated with weight loss in obesity.

Main Methods:

• Sixty male rats were induced into obesity using a high-fat/high-sucrose (HF/HS) diet for 4 months.
• Four regimens were applied for 2 months: HF/HS diet + exercise, WBR diet + exercise, HF/HS diet + inactivity, WBR diet + inactivity.
• Bone parameters were assessed using DXA, Piximus, histomorphometry, 3D microtomography, and biochemical markers (osteocalcin, CTX).

Main Results:

• Both WBR diet and exercise significantly reduced body weight, global fat, and visceral fat mass.
• The WBR diet alone did not alter total and tibia bone mass/BMD but decreased tibia bone volume, Tb.Th, and anisotropy, and reduced bone formation rate (BFR/BS) in L2 vertebrae.
• Exercise significantly improved tibia BMD, likely by inhibiting bone resorption, as indicated by decreased CTX levels and osteoclast number, without altering osteocalcin.

Conclusions:

• A weight-loss-inducing diet in obese rats did not negatively impact overall bone mass or BMD, despite causing micro-architectural changes.
• Moderate-intensity exercise improved tibia BMD in obese rats, suggesting a protective effect against bone loss during weight reduction.
• Exercise appears to benefit bone density in obese individuals undergoing weight loss, primarily through reduced bone resorption, without significant trabecular or cortical adaptation.