In Australians with European roots, people whose bodies use insulin more efficiently tend to burn fewer calories while at rest — like their bodies are on a lower energy setting when they're not moving.

In people of European descent living in Australia, scientists found that two ways of measuring how well the body uses insulin—using both sugar and fat levels in the blood—are better linked to how many calories you burn while resting than a simpler method that only uses sugar. This suggests that looking at both sugar and fat might tell us more about your metabolism than sugar alone.

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.

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.