Low vitamin D levels are commonly found with obesity. The first study reviewed here investigated the effect of weight loss through diet and exercise on serum levels of vitamin D (Mason, et al. 2011). Vitamin D concentration was measured at the start of the study and 12 months later.The results showed that greater weight loss was associated with increased vitamin D. As weight loss increased vitamin D levels increased.The next study reviewed evaluated vitamin D levels in normal weight, overweight and obese cancer patients (Vashi PG, et al. 2011). The participants were both females and males with different kinds of cancer.The conclusion of the research was that obese cancer patients had significantly lower levels of serum vitamin D when compared with the other groups.If your body mass index is on the high side you need to supplement with more vitamin D, but what is interesting is that your vitamin D level would increase somewhat just by losing some weight.