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

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 35kg/m2 and osteoarthritis. The patients received a formula diet with two intake levels of a normocaloric hyperproteic formula (1035kcal (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.