The rate at which we metabolize caffeine may affect our weight, a new study finds, but further research is needed to determine whether drinking more coffee is actually beneficial.
Dr Dipender Gill, a clinician scientist at Imperial College London, was part of the team of researchers involved in the study.
The new study investigates the influence of genetics, making the findings stronger than previously conducted studies, he said.
Previous research has been unable to show a cause-and-effect relationship between caffeine and body weight – and Dr Gill hopes the new findings will be used to “guide further research, including potentially clinical studies”.
“Ninety-five percent of the caffeine in your body is metabolized by an enzyme,” and two genes called CYP1A2 and AHR affect the function and levels of this enzyme, he told the Pennsylvania News Agency.
Looking at these genetic variants that cause people to metabolize caffeine more quickly or more slowly, the study found that slower metabolizers had higher plasma caffeine levels, a lower body mass index, and a lower risk of diabetes.
“This is the effect of plasma caffeine,” he said.
At a population level, this means that people who metabolize caffeine more slowly are more likely to be thinner and have a lower risk of developing diabetes, Dr. Gill said.
“If you’re a faster metabolizer, you have lower plasma caffeine levels, and on average, at a population level, you have a slightly higher risk of diabetes and a slightly higher body mass index.”
It is hoped that the current research will guide further research, including whether drinking more coffee can help people stay smarter.
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However, he made it clear that people should not change their habits now.
“Of course, people shouldn’t start drinking more coffee or tea in an attempt to lose weight, also because coffee and tea, as well as caffeine, can also have adverse effects.
“So some people may find it difficult to sleep, some people experience heart palpitations, so I don’t think people should change their lifestyle or behavior based on this study, but our findings should be used to guide further research, including potential clinical research.”
Dr. Gill said it’s unclear how much of the population metabolizes caffeine faster.
The study included nearly 10,000 people who participated in six long-term studies.
The new study was published in the journal BMJ Medicine.