Collectively , these outcomes support a volumetric dilution of vitamin D. The slopes of the respective regression lines , however , indicate a smaller increase in 25OHD than would be expected from a direct mobilization of stores into the circulation .
Hence , sequestration of 25OHD and its conversion to inactive metabolites would also play a role .
The purpose of this review was to confirm a volumetric dilution of vitamin D in obesity .
It was based on the hypothesis that weight loss , particularly fat loss , would increase serum 25-hydroxyvitamin D ( 25OHD ) in the obese .
Cross-sectional and prospective cohort study of serum 25-hydroxyvitamin D level and obesity in adults: the HUNT study.
Experimental studies suggest that vitamin D modulates the activity of adipocytes . The authors examined baseline serum 25-hydroxyvitamin D ( 25(OH)D )  level in relation to prevalent and cumulative incident obesity in Norway . A cohort of 25,616 adults aged 19 - 55 years participated in both the second and third surveys of the Nord-Trøndelag Health Study ( HUNT 2 ( 1995 - 1997 ) and HUNT 3 ( 2006 - 2008 ) ) .  Serum 25(OH)D levels measured at baseline and  anthropometric measurements  taken at both baseline and follow-up were available for a r and om sample of 2,460 subjects . Overall , 40 % of the 2,460 subjects had a serum 25(OH)D level less than 50.0 nmol/L , and 37 % had a level of 50.0 - 74.9 nmol/L. The prevalence and cumulative incidence of obesity , defined as body mass index ( weight (kg)/height (m)(2 ) ) ≥30 , were 12 % and 15 % , respectively . Lower serum 25(OH)D level was associated with a higher prevalence of obesity . In the 2,165 subjects with baseline BMI less than 30 , a serum 25(OH)D level less than 50.0 nmol/L was associated with a significantly increased odds ratio for incident obesity during follow-up ( adjusted odds ratio = 1.73 , 95 % confidence interval : 1.24 , 2.41 ) . When prevalent and incident obesity were classified according to waist circumference ( ≥88 cm for women , ≥102 cm for men ) , similar results were obtained . In addition to prevalent obesity , a serum 25(OH)D level less than 50.0 nmol/L was significantly associated with new-onset obesity in adults
Collectively , these outcomes support a volumetric dilution of vitamin D. The slopes of the respective regression lines , however , indicate a smaller increase in 25OHD than would be expected from a direct mobilization of stores into the circulation .
Hence , sequestration of 25OHD and its conversion to inactive metabolites would also play a role .
The purpose of this review was to confirm a volumetric dilution of vitamin D in obesity .
It was based on the hypothesis that weight loss , particularly fat loss , would increase serum 25-hydroxyvitamin D ( 25OHD ) in the obese .