Does vitamin d make you gain weight or not?

No evidence. So far, no scientific evidence supports this hypothesis.
No. In fact, vitamin d may help you lose weight. Several studies have shown obese people tend to have lower vitamin d levels than normal weight people. Low vitamin d levels are associated with an increased risk of diabetes, both type 1 and 2. If vitamin d increased weight it is likely due to sensitivity and/or allergy to lanolin, the most common source of vitamin. Then fluid retention could result.