Imperial College London’s research concluded that the speed at which caffeine is metabolised could have an impact on weight (Getty Images/iStockphoto)
Higher blood caffeine levels could help people to stay slim, a new study has found.

The research – conducted by Imperial College London – concluded that the speed at which caffeine is metabolised could have an impact on weight, though more in-depth research is needed to specify whether drinking more coffee could help to keep the weight off.

The research surveyed close to 10,000 people who were taking part in six longer-term studies. It concluded that participants with higher plasma caffeine levels enjoyed a lower body mass index (BMI), alongside a lower risk of developing type two diabetes.

By contrast, the study found that metabolising caffeine at a quicker rate suggests a slightly higher risk of developing type two diabetes alongside a higher BMI. However, it is not yet clear what proportion of the population do metabolise caffeine more quickly.

“95% of your caffeine is metabolised by an enzyme”, Dr Dipender Gill, a clinical scientist at Imperial College London, told the PA news agency. “Two genes called CYP1A2 and AHR affect the function and level of that

“So, using these genetic variants that cause people to metabolise caffeine faster or slower, we found that slower metabolisers have higher plasma (blood) caffeine levels, and those with higher plasma caffeine levels go on to have a lower body mass index and a lower risk of diabetes.

“It’s the plasma caffeine that’s doing that.”

However, Dr Gill does not advise that anyone should change their habits yet. As he notes, drinking more caffeinated drinks – tea and coffee included – can impact sleep quality and cause heart palpitations.

“Our findings should be used to direct further research including potential clinical studies”, he added. Elsewhere, one 2019 study found that caffeine intake could promote weight, BMI and body fat reduction. Across 606 participants,
for every doubling in caffeine intake, the mean reduction in weight, BMI and fat mass increased by up to 28%.

Likewise, one study conducted by Harvard T.H. Chan School of Public Health researchers in 2020 found that drinking four cups of coffee each day could reduce body fat by around 4%. Assessing whether coffee consumption reduces the risk of developing type two diabetes, it examined 126 overweight, non-insulin sensitive adults. Coffee can also increase metabolic rate, meaning that the body is able to burn calories quicker when resting. The higher the metabolic rate, the easier the weight loss, though coffee’s potentially positive impact has been shown to reduce with age.