Could caffeine reduce body fat and diabetes risk?

New research suggests high blood caffeine levels may be beneficial for weight and type 2 diabetes risk. But is this actually the case?

Tea and coffee-lovers may have been cheered by the news of research suggesting that high levels of caffeine in the blood may reduce body fat and risk of type 2 diabetes.  

The study, published in the British Medical Journal Medicine, found that high blood caffeine levels are also linked to having a healthier weight. They said this finding explains some, though not all, of the reduced risk of diabetes, since type 2 diabetes is linked to being overweight.  

Cup of coffee, featuring a heart shape in the froth, beside coffee beans.Credit: Shutterstock/Billion Photos

And they called for further research into whether calorie-free caffeinated drinks (such as coffee without milk or sugar) could be useful in reducing the risk of obesity and type 2 diabetes. But is caffeine really good for you?  

Exceptional spoke to Dr Sunni Patel – a nutritional therapist who researches type 2 diabetes and heart disease, and the founder of health coaching and food education platform Dish Dash Deets – for his take on the findings. He said that whilst this is an interesting study that adds to our knowledge and confirms earlier findings about caffeine, he is cautious about whether it could mislead people.   

“This study shouldn’t mean, if you don’t drink coffee – start, and if you drink coffee – drink more.”

The study didn’t look at how much tea or coffee people actually drank. Instead, it looked at two genetic variations which are known to lead to higher caffeine levels in the blood (because coffee is removed from the body more slowly). It used those as a way of comparing people with higher and lower caffeine levels. This technique can also be useful because it strips out other factors that might confuse the results (for example, people who drink more coffee might smoke more, or eat more biscuits). 

Patel says: “This study helps us to understand possible associations (not causes) of substances within our body and risk factors. This shouldn’t be a study that people take to mean ‘if you don’t drink coffee – start, and if you drink coffee – drink more.’” 

Tea, which contains caffeine, pouring from a blue teapot into a blue cup illustrating foods that help you sleepCredit: Shutterstock/Africa Studio

He also notes that the research didn’t find that caffeine reduced the risk of heart disease, even though it shares some of the same risk factors as obesity and diabetes. 

“We can’t say caffeine is a wonder drug,” adds Patel. “We shouldn’t forget far more effective lifestyle strategies for managing diabetes and weight – the biggest being diet and movement, which have both been found to substantially reduce the risk of both conditions.” 

He also says there are limitations to this study, such as the fact that it only looked at people of European origin.  

Patel shares his tips for safe caffeine intake 

  • Don’t drink coffee first thing in the morning – Try not to drink coffee immediately on waking up. Caffeine can increase levels of cortisol (the hormone that signals your body to be awake and responsive – also known as a stress hormone), but they will be at their peak first thing in the morning anyway. 
  • Try not to have caffeine too late in the day – Caffeine can affect your natural body clock and sleep quality. I suggest having caffeine no later than 1pm, as the half-life of caffeine (the time it takes for half of the amount to leave the body) is between 1.5 and 9.5 hours, with an average time of five hours.  
  • Notice the impact that caffeine has on your body – Caffeine can block the effects of adenosine (a compound that promotes sleep). But once the caffeine wears off, your body may experience a build-up of adenosine that hits you all at once. This could leave you feeling more tired in the day. 
  • Ask yourself: ‘What else is in my morning cup?’ Think about the calories of milk and sugar, which can affect diabetes and obesity. If you don’t already, try drinking black tea or coffee, and avoid adding sugar or artificial sweeteners.  
  • Stay hydrated – Drink lots of water, especially if the caffeine is making you go to the toilet more often. 
  • Find other alternatives to get the pick-me-up that you need Have a walk, exercise or drink other cold drinks, shakes or smoothies. If you really need caffeine, try having it later in the morning or early afternoon. 

How much caffeine should you have in a day?

There are no official recommendations in the UK for caffeine intake, although pregnant women are advised to have less than 200mg per day (there’s typically 100mg in a mug of instant coffee, 140mg in a mug of filter coffee, or 75mg in a mug of tea).   

The British Heart Foundation says a moderate amount of tea or coffee (four or five cups a day) should be fine for most people. 

Patel warns that increasing your caffeine intake can have harmful effects for some people. For example, people with anxiety, insomnia or high blood pressure may notice worsening of their symptoms. 

“Caffeine is still likely one of the most readily available addictive substances, so always consume it in moderation.” 

“Maintaining a healthy weight, eating a balanced diet, and staying active are ways to lower your type 2 diabetes risk.”

Many coffee-based drinks are also higher in sugar than you might think – especially the versions available from high street coffee shops, which tend to be flavoured with syrups. Patel says: “A lot of these syrups are calorific and have a high sugar content. This would influence glucose and insulin levels, which is important to balance in people with obesity and/or those with or at risk of diabetes.” 

Group of people clinking their mugs together.Credit: Shutterstock/sebra

What’s next?

Following their findings, the researchers said it is now worth exploring if calorie-free caffeinated drinks should be used to reduce obesity and type 2 diabetes. 

Research communications manager at Diabetes UK, Dr Faye Riley, says: “This study is an interesting addition to the evidence on the links between caffeine, bodyweight and type 2 diabetes. We still need to understand how this translates into practical advice for people trying to reduce their risk of type 2 diabetes. 

“However, there is plenty of evidence to show that maintaining a healthy weight, eating a balanced diet and staying active are effective ways to lower your risk of the condition.”  

Gemma Harris

Written by Gemma Harris she/her


Gemma Harris has been a journalist for over seven years and is a self-confessed health and wellbeing enthusiast, which led her to specialise in health journalism. During her career, she has worked with top editors in the industry and taken on multiple high-discipline fitness challenges for certain outlets. She is particularly passionate about nutrition; after being diagnosed with irritable bowel syndrome in 2016, she discovered her fascination for gut health and founded – a dedicated space for providing a hopeful outcome for people with gut issues. Gemma’s core aim is to help others through her writing.

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