Zero sugar, more problems? Study reveals surprising gut health effects

Eliminating sugar from your diet may seem like the key to healthy eating, but research suggests it could have unintended effects on digestive health.

A study presented at ENDO 2026, the Endocrine Society's annual meeting, suggests that a total lack of sucrose, or table sugar, may harm gut health and disrupt the body's natural metabolism.

To explore how the total absence of dietary sugar impacts the body, researchers at the Dasman Diabetes Institute in Kuwait City conducted a 16-week study on two groups of mice. Both groups were placed on a low-fat diet, but with one critical difference.

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One group consumed a low-fat diet that included a standard amount of sucrose, while the other group ate a low-fat diet that was completely sugar-free, according to the study's press release.

Throughout the trial, the scientists monitored a wide variety of physiological factors, including the animals' weight, glucose tolerance, insulin sensitivity, hormone levels, internal inflammation and the specific composition of their gut bacteria.

The study outcome suggested that completely removing sugar caused several unexpected health problems.

"Completely removing sucrose from a low-fat diet may unexpectedly disrupt gut health and promote inflammation and metabolic dysfunction," Rasheed Ahmad, principal scientist and head of the Immunology & Microbiology Department at the Dasman Diabetes Institute, said in the release.

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Even though the mice on the sugar-free diet did not gain any extra weight compared to the control group, their internal health indicators deteriorated.

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The animals that lacked sucrose developed an imbalance in their gut microbes and increased inflammation within the intestines and liver.

They also showed signs of poor glucose regulation, insulin resistance and cellular changes associated with fatty liver disease, according to the research.

"The findings suggest that complete removal of sucrose from a low-fat diet may negatively affect gut microbiota and metabolic health," Ahmad concluded.

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While the risks of high-sugar diets are well-established, the researchers noted that little attention has been given to the effects of completely eliminating sugar from low-fat meals.

Scientists say these new findings highlight that dietary carbohydrates play a valuable role in supporting balance between the immune system and the gut microbiome.

Because this research was conducted on mice over a relatively short 16-week period, further clinical trials are necessary to determine whether a completely sugar-free diet causes the same gut and liver inflammation in humans.

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Additionally, the study focused specifically on removing sucrose from low-fat meals, meaning the results might not apply to people eliminating sugar while following higher-fat or ketogenic eating plans, the researchers noted.

The team believes that future dietary guidelines may shift away from strict, absolute sugar restrictions and instead place a greater emphasis on maintaining a diverse, healthy population of gut bacteria through balanced nutrition.

"In the long term, these findings could help improve strategies for preventing and managing metabolic disorders, fatty liver disease and chronic inflammatory conditions," Ahmad said.