Choosing to have diet drinks with your meals could lead to weight gain, scientists believe.
Many people choose beverages with artificial sweeteners rather than the ‘full-fat’ sugar versions to watch their waistlines.
But research found that when consumed with a carbohydrate, such as fries, the body’s metabolism is impaired.
The brain’s ability to perceive sweet taste also changed, which, over time, may damage how the body copes with real sugar.
Sweetened drinks on their own had no negative effect, the study on 45 people over two weeks showed.
There has been a long-standing debate about whether diet sodas, filled with sweeteners such as sucralose, are as healthy as they seem.
The latest findings suggest its not consumption of sweeteners, but what they are consumed with, that affects the body.
Professor Dana Small, who led the study at the University of Yale, said: ‘Our findings suggest that it’s OK to have a Diet Coke once in a while, but you shouldn’t drink it with something that has a lot of carbs.
Ordering a diet drink with your fries could lead to weight gain, scientists believe
‘If you’re eating French fries, you’re better off drinking a regular Coke or better yet water.
‘This has changed the way that I eat, and what I feed my son. I’ve told all my friends and my family about this interaction.’
Previous research has suggested that drinking diet drinks may make people more likely to gain weight because people who have them feel they deserve a sweet treat afterwards.
And the chemicals in artificial sweeteners may change the bacteria in the gut and make people more likely to gain weight or develop diabetes, experts have previously said.
The latest study was designed to test whether or not repeated consumption of an artificial sweetener would damage how the brain perceives sweet taste.
The theory is called ‘uncoupling’, and suggests consuming sweet foods without any real calories reduces the body’s response to real sugar.
It could potentially mean that people put on weight easier, develop glucose intolerance or even get diabetes.
The study suggests that drinking diet drinks on their own does not appear to affect the body’s response to sugar. Instead, this effect was only observed when the drinks were consumed with a carbohydrate.
Sweetened drinks on their own had no negative effect, the study on 45 people showed
DIET DRINKS ‘INCREASE STROKE RISK’
Adults who have at least one diet drink a day are three times more at risk from a stroke or dementia, research revealed in 2017.
Scientists said the sugar-free drinks should no longer be regarded as the healthier alternative and urge the public to stick to water or milk.
Their study of almost 4,400 adults also suggests diet drinks are more likely to cause strokes and dementia than those full of sugar.
There was no link between sugary beverages and either of the illnesses – although the researchers aren’t encouraging people to drink them either.
The team of scientists from Boston University believe the artificial sweeteners including aspartame and saccharine may affect the blood vessels, eventually triggering strokes and dementia.
Diet drinks account for a quarter of the sweetened beverages market but there is growing evidence they are not as healthy as previously thought.
The study enrolled 45 people between the ages of 20 and 45 who didn’t normally have low-calorie sweeteners.
All of them were healthy and had no problem with their metabolism, according to paper published in the journal Cell Metabolism.
They each consumed seven low-calorie drinks in a lab over a two week period. Each drink contained sweeteners the equivalent of two sachets of Splenda.
Some of the volunteers had a powdered carbohydrate, called maltodextrin, added to their drinks. This was intended to serve as a control.
But to the researchers’ surprise, the control group showed the observed decreases the brain’s response to sweet taste, as measured by MRI scans.
The body’s insulin sensitivity, which is how efficient the body uses insulin, and glucose metabolism, which is how the body breaks down sugar to use for energy, was also impaired.
Taking this into account, the researchers added a second control group where those taking part were given drinks with only maltodextrin in.
There was no evidence that having these drinks affected insulin sensitivity or glucose metabolism.
Professor Small said: ‘When the drink was consumed with just the low-calorie sweetener, no changes were observed; however, when this same amount of low-calorie sweetener was consumed with a carbohydrate added to the drink, sugar metabolism and brain response to sugar became impaired.
‘This would be important because sweet-taste perception might lose the ability to regulate metabolic responses that prepare the body for metabolizing glucose or carbohydrates in general.’
Professor Small speculated as to why the drinks with both sweeteners and maltodextrin may have produced the observed effects.
She suggested that diet drinks may confuse the gut, which sends inaccurate messages to the brain about the number of calories present.
‘Perhaps the effect resulted from the gut generating inaccurate messages to send to the brain about the number of calories present,’ Professor Small said.
‘The gut would be sensitive to the sucralose and the maltodextrin and signal that twice as many calories are available than are actually present.
‘Over time, these incorrect messages could produce negative effects by altering the way the brain and body respond to sweet taste.’
Dr Sarah Berry, a nutrition scientist at King’s College London, said the study ‘only investigated one type of sweetener’.
‘From a public health perspective, this research is relevant in the context that we typically consume sweeteners alongside carbohydrate containing foods.
‘For example, sweeteners are found in many refined low calorie and low sugar foods in conjunction with other carbohydrates.
‘As with all foods and drinks, occasional consumption of diet drinks or foods containing sweeteners is not going to be harmful to health.
‘However, this research supports previous findings to suggest that we should not see diet drinks as a healthy alternative to sugar sweetened drinks.
‘The results from this study do not support the suggestion that we would be better off swapping diet coke for full sugar coke, partly because diet coke does not contain the specific sweetener – sucralose – that this study looks at.
‘We should not be swapping diet drinks for full sugar drinks, but should be encouraging the consumption of water.’
Studies have linked consumption of them through foods and diet drinks to diabetes, weight gain and cancer.
One study suggested that sugar-free drinks may also increase a woman’s risk of heart attack or stroke by almost a third.
The American Heart Association and American Stroke Association examined more than 80,000 women and published their findings in February 2019.
Women who drank fizzy sugar-free drinks regularly were 31 per cent more likely to have a stroke caused by a blood clot, the research found.
They were 29 per cent more likely to develop heart disease and 16 per cent more likely to die, when compared to women who rarely drank them.
Another study from scientists at the WHO International Agency for Research on Cancer in Lyon suggested that drinking just two glasses of diet drink a day increases the risk of an early death.
The global study of more than 450,000 adults in 10 countries – including the UK – found that daily consumption of all types of soft drinks was linked with a higher chance of dying early.
But the rates for those drinking artificially-sweetened beverages were significantly higher than those consuming full sugar versions.
The scientist said it would be ‘prudent’ to cut out all soft drinks and have water instead.
Industry bodies have hit back in light of the fact regulatory bodies have consistently confirmed their safety, and dietitians have long advised sticking to low calorie options instead of full fat sugary versions.
WHAT ARE THE DANGERS LINKED TO SWEETENED DRINKS?
SUGAR SWEETENED DRINKS
Drinking large amounts of sugar in drinks such as pop, soda and juices can lead to serious health problems, including weight gain, tooth decay and diabetes.
Some drinks contain upwards of 40 grams of sugar—equivalent to about 10 teaspoons of sugar—and 200 or more calories in a 12-ounce serving.
The NHS says more than 20 per cent of the added sugar in adult diets comes from soft drinks and fruit juice — and as much as a third for children aged between 11 and 18.
Researchers at Oxford University calculated the impact the Government’s sugar tax levy, introduced in April 2018, would have on obesity in the UK.
They found obesity would drop by 9.8 per cent in children aged four to ten.
In March, Harvard School of Public Health concluded that as well as weight gain, diabetes, heart disease and stroke, the more sugary drinks a person consumed the more their risk of early death from any cause increased. The link with heart disease was particularly strong.
The study, in the journal Circulation, looked at 117,000 Americans over three decades. Those who drank two or more cans of sugary drinks a day had a 31 per cent higher risk of early death from cardiovascular disease — and each further drink was linked with an astonishing 10 per cent increased risk.
Researchers at the Meyer Cancer Centre at Weill Cornell medical school, US, have announced they are starting to assess whether sugar ‘feeds cancer’.
Sweetened soft drinks – such as cordial or fizzy pop – increases cancer risk by 19 per cent, according to a study conducted by researchers from the Paris 13 University, Avicenne Hospital and The French Public Health Agency in July.
The researchers could not be clear if sugary drinks are directly causing the increase in risk. The sugary drinks may lead to obesity which is a well-known risk factor for various types of cancer.
ARTIFICIALLY SWEETENED DRINKS
Experts have long debated whether sweeteners, which include aspartame, saccharin and sucralose, are safe.
Studies have linked consumption of them through foods and diet drinks to diabetes, weight gain and cancer.
But industry bodies have hit back in light of the fact regulatory bodies have consistently confirmed their safety.
In February, research by the American Heart Association and American Stroke Association found two cans of sugar-free fizzy drinks per day could increase a woman’s risk of a heart attack or stroke by almost a third.
The major study of over 80,000 women found those who regularly drank fizz were 31 per cent more likely to have a stroke caused by a blood clot, 29 per cent more likely to develop heart disease and 16 per cent more likely to die, when compared to women who rarely drank them.
Another study in February, published in the journal Environmental Science and Pollution Research International, looked the effects of artificial sweeteners on mouse embryos.
In pregnant mice given sweeteners, malformations of mammary glands were seen in foetuses at 18 weeks, while four-week-old mice given sweeteners suffered ‘a decrease in the length of the body, limbs, and tail’.
Another study, published in the journal Metabolic Brain Disease in May, raised concerns about the impact of sweeteners on brain development.