Effect of weight loss on bone metabolism in postmenopausal obese women with osteoarthritis

Abstract Background The choice of hypocaloric diets in obesity can affect bone health. Aims The aim of this study is to assess the effect of a hypocaloric diet in postmenopausal obese women and to determine the influence of weight reduction on bone metabolism. Methods This was a non-randomised, single-treatment study in 96 postmenopausal women with a body mass index (BMI) greater than 35 kg/m 2 and osteoarthritis. The patients received a formula diet with two intake levels of a normocaloric hyperproteic formula (1035 kcal (25% protein)). Anthropometry and biochemistry with CrossLaps, osteocalcin, parathyroid hormone (PTH) and 25-OH vitamin D were measured. Consumption of protein, calcium and vitamin D were determined at the beginning of and 3 and 6 months into the study. The response to treatment was compared (high-responder (HR): weight loss greater than 15%, and low-responder (LR): weight loss less than 15%). Results The mean age was 64.2 (7.5) years. After 6 months of treatment, a weight loss of 10.2% (8.2–13.8) was observed. There was a significant increase in vitamin D (HR: 21.8% (36.2) vs. LR: 22.7% (36.9), p = 0.93) and CrossLaps (HR: 26.8% (19.5–35.2)) vs. LR: 13.3% (−6.1 to 27.9), p = 0.01). The loss of more than 15% of initial body weight was an independent risk factor for an increase in CrossLaps (OR: 4.22 (1.1–16.8), p = 0.04). Conclusions In postmenopausal obese women, weight loss was associated with an increase in the biochemical parameters of bone resorption. The increase in resorption parameters was related to the magnitude of weight loss.