In a Nutshell:
- Green tea very mildly helps in promoting weight loss if consumed in moderate doses
- The weight loss effect is largely mediated by caffeine, EGCG, and catechin that are known to slightly boost metabolism and fat breakdown among consumers
- The metabolism boosting effects of Green tea can be increased by supplementing it with exercise and diet modification
What is Green Tea?
Camellia sinensis (or Green tea) is a popular beverage around the world. Green tea and green tea extract are believed to help in weight loss by boosting metabolism, breaking down fat stores, and reducing fat absorption in the body.
There is some evidence that regular green tea consumption can very slightly help in promoting weight loss.
The metabolism boosting effects of green tea are attributed to:
- Caffeine: Green tea contains caffeine (1 cup contains about 24-40 mg of caffeine) which works as a mild stimulant in promoting fat oxidation and enhancing exercise performance.
- Epigallocatechin gallate (EGCG): Green tea contains compounds like epigallocatechin gallate (EGCG) that are known to boost metabolism.
- Norepinephrine (noradrenaline): There is also evidence that green tea consumption enhances the effect of some fat burning hormones in the body such as norepinephrine (noradrenaline) by inhibiting its breakdown.
- Catechin: Green tea also contains a flavonoid (catechin) that works an antioxidant. When consumed, it metabolizes excessive fat stores.
In short, green tea has a positive but very slight impact on promoting weight loss when consumed in moderate doses. It is noteworthy that traditional weight loss methods such as exercise or diet modification results in better outcome.
Dosing for Weight Loss
It is recommended that 2-3 cups of hot green tea per day at periodic intervals can speed up metabolism and may help in slight weight loss.
Some studies also suggest that metabolism boosting effects of Green tea can be enhanced by consuming it prior to exercise or workout (3). A new study suggested that fat oxidation is 17% higher among subjects who received green tea prior to workout than control subjects who received a placebo beverage (3).
Nuances / Safety
- Excessive intake of green tea is not recommended as high caffeine content may cause jitteriness or agitation.
- Individuals who have a history of heart diseases, hypertension should avoid excessive intake of green tea.
- Green tea extract is associated with a wide range of side effects such as nausea, abdominal discomfort, constipation, blood pressure changes and liver damage and therefore should be avoided.
Other proven benefits of Green Tea
- Green tea is rich in powerful antioxidants such as catechins that wards off free radicals and reactive oxygen species.
- Green tea consumption also helps in the regulation of blood cholesterol.
Strength of Evidence:B
The only data available is from observational studies, which are inconclusive and usually cannot be reproduced in higher quality clinical studies.
Although Green tea is a common ingredient in several weight loss supplements, there is inconclusive evidence that Green tea alone can promoting significant weight loss without any other dietary or physical intervention. When consumed in moderate to high doses, it may slightly promote metabolism and fat breakdown.
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