A high blood caffeine level might curb the amount of body fat a person carries and their risk of type 2 diabetes, suggests research published in the open access journal BMJ Medicine.

In light of these findings, the potential role of calorie free caffeinated drinks for lowering the risks of obesity and type 2 diabetes is probably now worth exploring, say the researchers.

Previously published research indicates that drinking 3-5 daily cups of coffee, a rich source of caffeine, is associated with a lower risk of type 2 diabetes and cardiovascular disease, note the researchers. An average cup of coffee contains around 70–150 mg caffeine.

But most of the published research to date has concerned observational studies, which can't reliably establish causal effects, because of the other potentially influential factors involved, the researchers note. What's more, it's difficult to disentangle any specific effects of caffeine from the other compounds included in caffeinated drinks and foods.