You hear a lot about the health benefits of green tea and one of the most intriguing is that green tea helps with fat loss. Green tea is an unfermented form of tea that retains more of the antioxidants that make green tea such a healthy sip. Drinking green tea is a rich source of a variety of polyphenols with antioxidant activity, including flavonoids and catechins. The catechin in green that’s currently the focus of most research is called epigallocatechin gallate, or ECGC. When you buy a green tea supplement, it usually contains a concentrated form of this catechin.
Why the interest in green tea? Based on preliminary studies, there’s some evidence that drinking substantial quantities of green tea may lower the risk of certain diseases, including type 2 diabetes, Alzheimer’s disease, and certain forms of cancer. However, more research is needed since many of these studies are observational. One of the more intriguing questions is whether green tea helps with fat loss.
Green Tea and Fat Oxidation
Green tea contains two components that could potentially help with fat loss: ECGC and caffeine. Both of these compounds activate the sympathetic nervous system, the fight-or-flight component. When the sympathetic nervous system goes into overdrive, it increases your heart rate and boosts metabolism and fat oxidation, the percentage of calories burned from fat as opposed to glucose. However, short-term studies looking at the impact of caffeinated green tea on fat burning and metabolism are mixed. Some studies show an increase in metabolism and fat oxidation at ECGC doses of as low as 300 mg, while others show no sustained boost even at doses of 600 mg.
One meta-analysis of 6 studies found that the combination of green tea catechins and caffeine boosted daily energy expenditure slightly more than caffeine alone but fat oxidation increased only slightly in response to a mixture of tea catechins and caffeine. Some studies show that green tea boosts fat oxidation during exercise while others do not. So, looking at fat oxidation and resting metabolic rate, the results are mixed, although taken as a whole, green tea at doses of 300 mg. and higher seems to modestly boost fat oxidation. The amount of green tea you would need to drink to get 300 mg. is around 6 cups.
The problem with drinking green tea to boost fat loss is you have to drink a lot of it and the effects on fat oxidation and resting metabolic rate are short lived. Can drinking it consistently lead to meaningful fat loss? Researchers carried out at a meta-analysis of 11 studies looking at the impact of green tea on weight loss and weight maintenance. This analysis showed that consumption of green tea catechins was linked with a reduction in body weight and better weight loss maintenance.
In addition, one study found that Japanese participants with high levels of visceral body fat experienced a reduction in body fat, waist circumference, BMI as well as reductions in blood pressure and LDL-cholesterol after taking green tea extract for 12 weeks.
Another way green tea could be beneficial for fat loss is by suppressing appetite. The catechins in green tea increase activity of the sympathetic nervous system and this helps suppress the desire to eat. A study published in the Journal of Clinical Biochemistry and Nutrition showed that polyphenols, in green tea and from other plant-based sources, boost the release of satiety hormones, like CCK, PYY, and GLP-1. Therefore, drinking green tea could aid in fat loss by decreasing calorie consumption.
Finally, a number of studies show that green tea improves insulin sensitivity. That’s a plus for people with insulin resistance and type 2 diabetes. Since insulin is a fat storage hormone, green tea may also help with weight loss in people who are insulin resistant. One caveat is that most of the improvement in insulin sensitivity is seen in people who are already insulin resistant or have type 2 diabetes.
The Benefits of Drinking Green Tea for Weight Loss Are Likely to Be Modest
Green tea extract is frequently a component in weight loss supplements and it’s also available as ECGC in supplement form. Considering the amount of green tea you have to consume to get the modest benefits on body composition, a supplement is more practical than drinking 6 or more cups of green tea daily. Should you take a supplement?
Green tea in supplement form has drawbacks you may not be aware of. Recently, the FDA issued warnings about concentrated green tea supplements. Green tea extract, but not drinking green tea, has been, rarely, linked with liver damage. Plus, supplements aren’t regulated like medications are and it’s possible that some supplements contain higher quantities of the extract than is listed on the label. At high doses, green tea and green tea supplements can elevate blood pressure and heart rate.
Other Benefits of Drinking Green Tea
It might not be practical to drink 6 cups of green tea daily to improve your body composition, but drinking green tea has other potential health benefits. If you drink it unsweetened, it’s a far better choice than sugar-laden drinks. As mentioned, drinking it may offer some protection against type 2 diabetes and Alzheimer’s disease – and some studies show it may modestly lower blood pressure. Plus, observational studies show that tea drinkers have up to a 30% lower risk of developing heart disease.
The Bottom Line
Green tea isn’t a miracle panacea for weight loss as some supplement makers would have you believe but it’s a healthy alternative to drinking sugar-sweetened beverages. The best formula for controlling your weight is still a whole food diet, physical activity, adequate sleep, and stress management. It’s not always easy – but it works.
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