To date, no specific reference levels have been established for obese or overweight subjects. The standards for the general population apply to these individuals, and they should be supplemented whenever found to be deficient. It would be interesting to know how frequent vit D deficiency is present in your community.

In our recent paper (Endocr. Pract. 2015;21), we have reported on BMI as a significant predictive factor for vit-d deficiency. I think there is no need for specific reference levels for obese subjects and they should be also supplemented in case of defficieny.  

Hi

VitD insufficiency/deficiency has been reported to be associated with high body weight, obesity and metabolic syndrome. Supplementation with VitD in those patients has been recommended. Please check the attached studies.

Wishes,

Bassem

Adiposity is one of many factors affecting links between vit D and some metabolic imbalance (such as insulin deficiency). Obese individuals may avoid sun exposure, and vitamin D (a lipophilic compound) may be trapped in adipose tissue, resulting in serum deficiency

Just started checking Vit D levels in depressed patients in the north of England, during late winter/early spring. All deficient so far despite being a sunnier winter than usual.

Obese need 2.5 to 3X as much vitamin D. 

http://vitamindwiki.com/tiki-index.php?page_id=3426

thank for the useful answers!

Can anyone suggest a sort of algorithm for estimate vitamin D deficiency and correct therapy?

Re: low Vit D in obese subjects is this due to it pooling in the excess fatty tissue. plus possibly less sun exposure due to sensitivity about  displaying their bodies in publuic?

A very important question. I agree they require a much greater dose than lean people for reasons discussed above.  However we are still unclear which reference value to target. The latter is important to clarify since bone health may need 50 nmol/L but other chronic diseases may need much more. Some argue that even for bone health, 50nmol/L (20ng/ml) is too little!  . 

The majority of Europeans and anybody living above 34 degrees latitude will be exposed to a vitamin D winter, and the majority of Europeans will have simple vitamin D insufficiency (25OHD