Tokyo, Japan — Scientists at the RIKEN Center for Integrative Medical Sciences have found a new way to reduce obesity by changing how the gut works. Their study shows that adding extra acetate to the gut helps reduce fat and liver mass in mice. However, this only works if certain gut bacteria—specifically from the Bacteroides group—are also present. The research was led by Dr. Hiroshi Ohno and published in Cell Metabolism.
Obesity is a global health crisis affecting millions. It increases the risk of heart disease, type-2 diabetes, and cancer. One of the known contributors to obesity is eating too many sugars and starches. In contrast, eating dietary fiber is known to reduce the risk of these diseases, even though humans cannot digest fiber on their own. When fiber reaches the large intestine, gut bacteria ferment it and produce beneficial compounds, including acetate.
Acetate is the most common of these byproducts and is known to support healthy metabolism. However, not everyone produces the same amount of acetate from fiber. To solve this problem, Ohno’s team developed a supplement called AceCel—acetate combined with cellulose. This ensures the acetate reaches the lower part of the large intestine, where it is most effective.
In the new study, researchers gave AceCel to both normal and obese mice. The mice lost body fat and liver mass but kept their muscle. Other similar byproducts did not have the same effect, proving that acetate was the key compound.
The team also studied how the mice burned energy. Mice that ate AceCel used more fat from their livers and burned fewer carbohydrates, similar to what happens during fasting or on a low-carb diet. This change in energy use helps promote weight loss.
Next, researchers looked at the bacteria in the mice’s guts. They found that mice fed with AceCel had more Bacteroides bacteria. To test the importance of these bacteria, they gave AceCel to mice with no gut bacteria or with specific Bacteroides species. Mice without any bacteria did not lose weight, but mice with Bacteroides did, confirming that both acetate and these bacteria are needed for the effect to work.
Further analysis showed that this combination led to more carbohydrate fermentation in the gut. As a result, less sugar was left for the body to absorb. This shift meant the mice used more fat for energy and stored less sugar in their livers, helping explain the reduced obesity.
“Developing a treatment or prevention strategy for obesity is an urgent issue that must be solved quickly,” said Dr. Ohno. “We found that acetylated cellulose can prevent obesity by changing how the gut microbiome functions. Our next step is to test its safety and effectiveness in humans. If successful, this compound could be used in functional foods to help prevent obesity.”
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