Vitamin D Levels and Weight Gain. D?

I've been gaining weight since the summer for reasons my nutritionist doesn't understand. I have not changed my eating or exercise habits. I eat healthy and nutritious meals. I finally decided to check my blood work and the only abnormality was high levels of vitamin D. I do not take any supplements so I do not understand where the high levels come from and/or if it has to do with the weight gain. As far as Dr. Google says, low levels of vitamin D causes weight gain, not high levels. The only other factor here is depression. There has been an overall increase in feelings of depression this winter although my food intake has not changed. What can be contributing to this weight gain and why the high levels of vitamin D?