We love coffee here at HuffPost UK ― not least because it’s been proposed as a potential way to lower dementia risk, and may even help our hearts too.
Still, research on the health benefits of caffeine is often conflicting.
The American Heart Association’s stance is that while some might be good for us, too much can be harmful – although it admits that even determining what constitutes “too much” can be tricky.
That’s partly because everyone processes caffeine differently ― and, as a 2023 study published in the British Medical Journal points out, those differences might be linked to our BMI, body fat, and even type 2 diabetes risk.
What’s the association?
We’ve written before at HuffPost UK about how some people are “slow” coffee metabolisers, and some people process it way faster.
This paper suggests that these differences ― which are genetically determined ― were linked to BMI, body fat, and even dementia risk among the 10,000 or so participants whose biobank data they used for the study.
“Genetically predicted higher plasma caffeine concentrations were associated with lower BMI and whole body fat mass,” the paper reads.
In other words, the more caffeine was present in people’s blood (because they metabolised it more slowly), the lower their BMI, body fat, and type 2 diabetes risk tended to be.
The researchers added: “Furthermore, genetically predicted higher plasma caffeine concentrations were associated with a lower risk of type 2 diabetes.”
About half of that effect seemed to come from lower BMI scores among people with more caffeine in their blood.
Researchers speculated that the other half might come from how caffeine affects our heat production (thermogenesis) and how we turn fat into energy (fat oxidisation).
Other studies have also noted a “robust association” of habitual coffee consumption with a lower risk of type 2 diabetes.
Does that mean I’ll lose weight if I drink more coffee?
That’s not what this paper says.
The study did not find a definite causal link between the amount of caffeine in someone’s blood and, say, BMI.
Still, reviews of multiple randomised controlled studies have linked caffeine to “faster” metabolisms, which may promote weight loss.
The authors of the 2023 BMJ study wrote that more clinical research is needed to explore the link further.