The Journal of Clinical Endocrinology & Metabolism Vol. 95, No. 9 4251-4257
Copyright © 2010 by The Endocrine Society
Themistoklis Tzotzas, Fotini G. Papadopoulou, Kostantinos Tziomalos, Spiros Karras, Kostantinos Gastaris, Petros Perros and Gerasimos E. Krassas
Department of Endocrinology, Diabetes, and Metabolism (T.T., F.G.P., K.T., S.K., K.G., G.E.K.), Panagia General Hospital, 55132 Thessaloniki, Greece; and Department of Endocrinology (P.P.), Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, United Kingdom
Address all correspondence and requests for reprints to: Gerasimos E. Krassas, M.D., Ph.D., F.R.C.P. (Lond), Chairman, Department of Endocrinology, Diabetes, and Metabolism, Panagia General Hospital, Nikolaou Plastira, 22, Nea Krini, 55132 Thessaloniki, Greece. E-mail: krassas at the.forthnet.gr.
Objective: The objective of the study was to examine changes of 25-hydroxy-vitamin D (25OHD) and PTH blood levels 4 and 20 wk after low-calorie diet-induced weight loss.
Methods: Forty-four obese women aged 40.6 ± 11.4 yr, body mass index (BMI) 36.7 ± 4.9 kg/m2 and 25 controls (BMI 22.9 ± 1.5 kg/m2) were examined. Anthropometric and cardiometabolic parameters and 25OHD and PTH levels were determined at baseline and 4 and 20 wk after a low-calorie diet.
Results: At baseline, 25OHD levels were lower in obese compared with control subjects (17 ± 6.0 vs. 23.8 ± 8.7 ng/ml, P < 0.001), whereas no differences were found in PTH levels. In all women, a negative correlation was found between 25OHD levels and body weight (BW) (r –0.32, P < 0.001), BMI (r –0.37, P < 0.001), waist circumference (r –0.26, P < 0.05), and percent fat mass (r –0.38, P = 0.001) as determined by bioelectrical impedance analysis.
The 4-wk low-calorie diet (n = 37) reduced BW and led to significant improvements in the homeostasis model assessment (HOMA) index and lipid levels.
The 20-wk low-calorie diet (n = 26) resulted in reduction of BW and BMI by 10%, HOMA index (4.7 ± 3.8 vs. 3.10 ± 1.7, P < 0.01), and lipids levels (except high density lipoprotein cholesterol) and increase in 25OHD (15.4 ± 6.0 vs. 18.3 ± 5.1 ng/ml, P < 0.05), compared with baseline. PTH levels were unchanged. The increase of 25OHD levels was associated with the reduction of insulin levels and HOMA index (r –0.43, P < 0.05).
Conclusions: Blood 25OHD levels were low in obese women and correlated inversely with severity measures of obesity. Weight loss of 10% after low-calorie diet increased 25OHD levels, and this increase was mainly associated with improvement of insulin resistance.