Metabolic diseases are on the rise, more than ever, and what if tea could be the key to tackling them? Yes, tea could be the answer to all your metabolic problems, including weight management! A recent study led by the São Paulo Research Foundation (FAPESP) found that a specific tea could be a potential treatment for reducing weight and significantly improving glucose sensitivity and insulin resistance. The findings of the study are published in the journal Cell Biochemistry & Function.
Magic tea?
Imagine sipping some hot tea and getting rid of that excess weight! The tea in question is our good old green tea. This ancient beverage is known for its medicinal and antioxidant properties. It has been widely studied for its beneficial effects on metabolic diseases, such as obesity and type 2 diabetes. The new study looked into the mechanisms of action of this infusion and revealed that green tea treatment reduced weight and significantly improved glucose sensitivity and insulin resistance in obese mice. The findings of the study suggest that green tea may hold significant potential in the fight against obesity and related metabolic diseases.Rosemari Otton, who led the research from the Interdisciplinary Graduate Program in Health Sciences at Cruzeiro do Sul University in São Paulo, Brazil, has dedicated more than 15 years to green tea research. Otton explains that her initial motivation came from curiosity about the truth behind the popular belief that the drink aids in weight loss.
The study
To understand the effects of green tea on obesity, the researcher used an animal model. They fed mice a high-calorie diet for four weeks, with both fat and what they call a ‘cafeteria diet,’ which mimics the Western diet. “We give them chocolate, filled cookies, dulce de leche, condensed milk… In other words, the same type of food that many people consume on a daily basis,” Otton said.The test animals then underwent the green tea experiment for another 12 weeks. The animals were on a high-calorie diet during this period; however, some of them began receiving standardized green tea extract at a dose of 500 mg per kilogram of body weight, administered intragastrically (via gavage).“It’s a method that ensures they all receive the exact dose we want to study. If we put it in water, for example, we’d have no way of knowing how much the animal actually ingested,” the researcher added. This amount would be equivalent to consuming about 3 grams of green tea per day, or three cups, for humans.
Not all green teas are beneficial
The researchers also noted that not all commercial green tea meets the necessary quality standards. “Ready-made tea bags do not always guarantee the quantity or quality of the compounds. The ideal for consumption would be to use standardized green tea extract, like that found in compounding pharmacies. This is a concentrated way of using the plant, with a guarantee of the presence of flavonoids, which are the health-beneficial compounds present in the green tea plant,” Otton added. One methodological difference in the study was the controlled room temperature. They placed the animals in a thermoneutral environment (28 °C) throughout the experiment. Animal facilities generally maintain an average temperature of 22 °C, which represents chronic cold for mice. “Excessive cold activates compensatory regulatory mechanisms in the animals’ bodies, causing them to expend more energy to stay warm. This can mask the real effects of any substance. If the animals are in a colder environment, the effect of the tea is enhanced by the activation of energy expenditure due to the cold. But by maintaining thermoneutrality, we were able to see the effects of green tea in a ‘clean’ way, without environmental interference,” she explained.Previous research showed that obese mice treated with green tea experienced a reduction of up to 30% in body weight. “If a person loses 5% to 10% of their body weight, that’s already a lot. So this result in animals is very significant,” the professor added.
Muscular effect of green tea
Obesity typically causes a reduction in muscle fiber diameter, but green tea prevented this muscle atrophy. “One way to assess muscle function is to look at fiber diameter. If it increases, we have more active muscle components. Green tea managed to maintain this diameter, showing that it protects muscle against the harmful effects of obesity,” Otton explains.They also evaluated the expression of genes related to glucose metabolism. They found that treatment with green tea increased the expression of Insr, Irs1, Glut4, Hk1, and Pi3k, the genes vital for glucose uptake and use in muscles. The activity of lactate dehydrogenase (LDH), an enzyme that is essential for glucose metabolism, was also restored.Otton also added that green tea does not affect the weight of lean animals, suggesting that it acts selectively against excess body fat. “It makes obese animals lose weight but keeps lean animals at a balanced weight. This shows that the tea seems to need an environment with excess nutrients to act, which supports the hypothesis that it acts directly on fat cells.”“Green tea is a complex matrix with dozens of bioactive compounds. We’ve tried to separate these compounds and study their effects individually, but the whole extract is always more effective. There’s a synergy between the compounds that we can’t reproduce when they’re isolated,” she added.
So, can drinking green tea really help humans?
Though the results in the study are striking, Otton emphasized that it is not yet possible to determine a safe and effective dose of green tea for humans. This is because of the variability of the extracts and the fact that each person behaves differently. “The ideal is chronic consumption, as we see in Asian countries. In Japan, for example, people consume green tea every day, throughout their lives, and obesity rates are low. But this is different from drinking tea for five months and expecting a miraculous weight loss effect,” she said.
“The idea is to have safe, natural, effective, and high-quality compounds. The Camellia sinensis plant offers this. We’re still studying all the compounds involved, but there’s no doubt that green tea, as a plant matrix rich in flavonoids, has important therapeutic potential,” she said.“What we see in animals doesn’t always reproduce in humans. But if we want to make this translation to real life, we need to think about all the details, such as ambient temperature. It’s these precautions that increase the validity of our data. We’re far from having all the answers, but we’re getting closer and closer,” Otton concluded.
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