A recent study of the Vitamin D levels of obese men and women over a 11 week period prior to beginning a calorie restricted diet, and during and after this diet showed a strong relationship to healthy high levels of Vit D and successful dieting.

For every  increment increase in the Vitamin D level in the dieting study participant, it was found they lost half a pound more weight.

Having higher levels of Vitamin D at the start of the diet also resulted in greater loss of abdominal fat. This abdominal fat being the most dangerous due to it's link to diabetes and heart disease.

Another potential piece to the weight loss puzzle was unveiled recently when researchers discovered there may be a link between vitamin D levels and shedding pounds.

Dr. Shalamar Sibley, an assistant professor of medicine at the university of Minnesota cautioned that more controlled clinical trials are needed to see if Vit D supplements will have any benefit in helping people loose weight during diets.

Excess levels of Vitamin D are toxic and any Vitamin D level taken as a supplement is best taken only after a blood test to make sure it is required.  Vitamin D3 is the safest supplement to take and most people absorb adequate Vitamin D through an average of 15 minutes a day (variable by time of year and time of day) from the sun with highly pigmented people needing up to 10 times more sun exposure to absorb the same amount of Vitamin D as a fair skinned person.  It is impossible to overdose on Vitamin D from  sunshine.  

I have just had my Vitamin D levels checked lin May 2019,  they were very low and I needed  to supplement under doctors and dietitian advice. In September 2009, they were at the low side of normal, I will re check them again soon and hope to be in the medium to high side of the normal range. I still take Vittamin D3 on dieticians recomendation. 

Remember that excess Vitamin D is toxic and do not self medicate.