|Obesity is associated with vitamin D deficiency. The reason is that the vitamin D is trapped within the fat and cannot easily exit. As a result, obese patients need at least twice as much vitamin D as a normal weighted individual in order to maintain a normal vitamin D status with a 25(OH)D between 30-60 ng/ml.
Wortsman J, Matsuoka LY, Chen TC, Lu Z, Holick MF. Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr 2000;72: 690-693.