In people of European descent living in Australia, having more or less vitamin D doesn’t seem to change how many calories your body burns at rest — any small effect vitamin D might have is probably canceled out by how it affects your body’s insulin response.

In Australians with European roots, having more vitamin D in your blood might help you burn more calories while at rest—but if your body is better at using insulin, that calorie-burning boost might not be as strong.

In people of European descent living in Australia, how much energy their body uses at rest might be linked to their vitamin D levels—but only if you use certain ways to measure insulin sensitivity. Some methods show a clear link, others don’t, so not all those methods are equally good for this kind of study.

If you have more vitamin D in your body, your body burns more calories while you're just sitting still—even if you don’t move more or eat differently.

In people who are overweight or obese, having more vitamin D in their body seems to be linked to how many calories they burn at rest, and this link happens because of how their body uses the vitamin D receptor gene — but not because of the PGC-1α gene.