Does Drinking Green Tea Support Weight Loss? Catechins Increase Insulin Resistance

It's a common staple among celebrities when it comes to weight loss, but is it really going to help you shed pounds? According to a recent study, actual evidence supports this theory: The extract found in the drink can be a critical compound that can help control a healthy weight or help you, in fact, lose weight, too. 

Evidence now confirms that green tea extract may be an effective herbal remedy used to maintain a healthy weight and lose weight, too. It does this by helping to regulate the glucose in type 2 diabetes. In order to ascertain whether green tea truly has this potential, led by Jae-Hyung Park and colleagues from the Keimyung University School of Medicine in the Republic of Korea.

Active ingredients in great tea help inhibit intestinal glucose and lipid uptake, which are a certain type of flavonoid called gallated catechins. The authors had previously suggested that the amount of gallated catechins necessary to reduce blood glucose concentrations can be achieved from a daily dose of green tea. However, the amount of green tea needed to decrease lipid uptake from the gut is higher and has been shown to have adverse effects in humans. Once in the bloodstream, gallated catechins can actually increase insulin resistance, which is a negative consequence especially in obese and diabetic patients.

Researchers tested the effect of the extract by giving mice the green tea extract alone as well as adding polyethelene glycol. They then compared these against the effects of two other therapeutic drugs that are routinely prescribed for type 2 diabetes. 

Results showed that green tea extract in isolation did not give any improvements in body weight and glucose intolerance. However, when green tea extract was given with polyethylene glycol, there was a significant reduction in body weight gain, insulin resistance and glucose intolerance in both normal mice on a high fat diet and diabetic mice. The polyethylene glycol had the effect of prolonging the amount of time the gallated catechins remained in the intestines, thereby limiting glucose absorption for a longer period.

Interestingly, the effects of the green tea extract in both the intestines and in the circulation were measurable at doses which could be achieved by drinking green tea on a daily basis. In addition, the effects of green tea extract were comparable to those found when taking two of the drugs which are currently recommended for non-insulin dependent diabetes.

The authors conclude that "dietary green tea extract and polyethylene glycol alleviated body weight gain and insulin resistance in diabetic and high-fat mice, thus ameliorating glucose intolerance. Therefore the green tea extract and polyethylene glycol complex may be a preventative and therapeutic tool for obesity and obesity-related type 2 diabetes without too much concern about side effects."

The finds from the study were published in the Springer journal Naunyn-Schmedeberg's Archives of Pharmacology.