For several years, sugar has been in the sights of doctors and researchers around the world. Consumed in excess, it promotes weight gain and increases the risk of diseases (type 2 diabetes, fatty liver, stroke, cavities, etc.). The WHO even recommends limiting free sugars to less than 10% of daily energy intake, or even 5%, to reduce these risks.
In this context, more and more people are turning to a sugar-free diet, convinced of doing good for their body. But is it really a good idea to completely eliminate fast sugars? Not necessarily. An American study presented at the ENDO 2026 congress suggests that removing sucrose (the sugar found on all tables) could greatly disrupt our metabolism and our microbiota.
Sugar-free diet: why researchers are warning about its possible effects
To carry out their work, researchers at the University of Kentucky followed 12 healthy mice, divided into two distinct groups. For 16 weeks, the first group received a diet low in fat (but high in sucrose), while the second followed a similar diet completely devoid of sugar. Important detail: both groups consumed the same number of calories.
The researchers then screened different metabolic indicators, including glucose tolerance and insulin sensitivity. They also studied the intestinal microbiota and the inflammatory state of the colon and liver.
The effects observed: disturbed blood sugar, inflammation and modified microbiota
Result ? At the end of 16 weeks, the weight of the animals was similar. But the mice deprived of sucrose showed several unexpected changes: poorer glucose regulation, signs of insulin resistance, an inflammatory reaction in the intestine as well as significant changes in their microbiota. Researchers also observed markers associated with non-alcoholic fatty liver disease, also called fatty liver disease.
So, contrary to popular belief, completely removing sucrose from a low-fat diet could
“unexpectedly disrupt intestinal health and promoteinflammation and metabolic dysfunctions“, underlines Rasheed Ahmad, principal investigator of the study.
Sugar and microbiota: a balance more complex than it seems
The intestinal microbiota brings together the billions of bacteria that live naturally in our digestive tract. Their balance therefore depends largely on what we eat. However, when this ecosystem is modified, the consequences can go beyond simple digestion and impact our metabolism, our immunity or even our inflammation.
For researchers, the elimination of sucrose could therefore be the trigger for this imbalance.
Sugar-free diet: why health professionals call for caution
For Pauline Pied, dietitian-nutritionist, these initial results must be interpreted with caution.
“This is in fact a study carried out in animals and not in humans. Then, in nutrition, extreme approaches (too much sugar/no sugar) are rarely the most relevant”, she explains.
In other words, the objective here is not to ban sugar at all costs, nor to reintroduce it into all your meals, but to better balance your carbohydrate intake, by favoring a varied and minimally processed diet.
“Besides, as dietitians, we never recommend “zero sugar” to our patients. Quite simply because, in terms of eating behavior, it generally does not work,” concludes the expert.
As is often the case in nutrition, moderation is good!