Improved nutritional status and bone health after diet-induced weight loss in sedentary osteoarthritis patients: a prospective cohort study

BACKGROUND/OBJECTIVES: Obese subjects are commonly deficient in several micronutrients. Weight loss, although beneficial, may also lead to adverse changes in micronutrient status and body composition. The objective of the study is to assess changes in micronutrient status and body composition in obese individuals after a dietary weight loss program. SUBJECTS/METHODS: As part of a dietary weight loss trial, enrolling 192 obese patients (body mass index >30 kg/m(2)) with knee osteoarthritis (>50 years of age), vitamin D, ferritin, vitamin B(12) and body composition were measured at baseline and after 16 weeks. All followed an 8-week formula weight-loss diet 415–810 kcal per day, followed by 8 weeks on a hypo-energetic 1200 kcal per day diet with a combination of normal food and formula products. Statistical analyses were based on paired samples in the completer population. RESULTS: A total of 175 patients (142 women), 91%, completed the 16-week program and had a body weight loss of 14.0 kg (95% confidence interval: 13.3–14.7; P<0.0001), consisting of 1.8 kg (1.3–2.3; P<0.0001) lean body mass (LBM) and 11.0 kg (10.4–11.6; P<0.0001) fat mass. Bone mineral content (BMC) did not change (-13.5 g; P=0.18), whereas bone mineral density (BMD) increased by 0.004 g/cm(2) (0.001–0.008 g/cm(2); P=0.025). Plasma vitamin D and B(12) increased by 15.3 nmol/l (13.2–17.3; P<0.0001) and 43.7 pmol/l (32.1–55.4; P<0.0001), respectively. There was no change in plasma ferritin. CONCLUSIONS: This intensive program with formula diet resulted in increased BMD and improved vitamin D and B(12) levels. Ferritin and BMC were unchanged and loss of LBM was only 13% of the total weight loss. This observational evidence supports use of formula diet-induced weight loss therapy in obese osteoarthritis patients.