Green tea has long been known as a healthy drink with antioxidant and healing properties.
Many people believe it can help with weight loss, and now science is offering more support for that idea. A new study led by Rosemari Otton from Cruzeiro do Sul University in São Paulo, Brazil, has shown that green tea can reduce body weight and improve blood sugar control in obese mice.
These results suggest that green tea could one day help people manage obesity and related conditions like type 2 diabetes.
The study, recently published in the journal Cell Biochemistry & Function, was funded by FAPESP. Otton and her team fed mice a high-calorie diet that mimicked what many people eat every day—foods like cookies, chocolate, and sweetened condensed milk.
After four weeks on this “cafeteria diet,” the mice continued eating the same way for another 12 weeks, but some began receiving a daily dose of green tea extract. This was given by gavage, a method that ensures each mouse receives exactly the right amount. The dose was equivalent to a human drinking about three cups of green tea per day.
The results were impressive. The green tea-treated mice lost weight and became more sensitive to insulin, meaning their bodies could better control blood sugar levels. These changes are very important for fighting obesity and preventing diabetes.
Otton explained that not all green tea products are created equal. Many ready-made tea bags may not contain enough of the beneficial ingredients. She recommends using standardized green tea extracts from compounding pharmacies, which guarantee the presence of flavonoids—the compounds thought to be responsible for green tea’s health benefits.
One important part of the study was that the mice were kept in a warm environment at 28°C, instead of the usual 22°C found in most labs. This prevented the animals from burning extra calories just to stay warm, giving a clearer picture of how green tea actually works.
The researchers also found that green tea helped protect muscles. Obesity can shrink muscle fibers, but in this study, green tea helped maintain their size and strength. The tea also increased the activity of genes and enzymes linked to better glucose use in muscles, making them more efficient.
Interestingly, green tea seemed to target only fat in obese mice. Lean mice didn’t lose weight, suggesting that the tea acts where it’s most needed. Otton believes that the tea works best in bodies with excess nutrients, and that its effects may depend on a protein called adiponectin.
When mice didn’t produce this protein, the tea had no effect, hinting that adiponectin plays a key role.
When researchers tested individual compounds from green tea, they found they weren’t as effective alone as the full extract. This shows that all the ingredients in green tea work together in a special way.
While these results are promising, Otton warns that we still don’t know the exact safe and effective dose for humans. People vary a lot, and results in animals don’t always apply directly to humans. But she points out that countries like Japan, where green tea is consumed daily over a lifetime, have lower obesity rates.
Otton hopes that natural and affordable treatments like green tea can be used more often, especially since some weight loss drugs are expensive and come with side effects. She believes that with more research, green tea could become an important tool in the fight against obesity.
If you care about weight management, please read studies about diets that could boost your gut health and weight loss, and 10 small changes you can make today to prevent weight gain.
For more health information, please see recent studies about low-carb keto diet could manage obesity effectively and results showing popular weight loss diet linked to heart disease and cancer.
The study is published in Cell Biochemistry and Function.
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