Green Tea Review
Green Tea originated from China and spread throughout the east. More recently, its popularity in the West has increased because of its potential fat-burning effects. We’re going to examine Green Tea thoroughly, as it is an ingredient that is found in diet pills extremely often.
Green tea has about a fourth of the caffeine content of a cup of coffee. Its caffeine is a combination of theophylline (stronger) and theobromine (weaker).
Many claims have been made about the health benefits of drinking Green Tea. The claims go from preventing Parkinson’s, Alzheimer’s, and certain forms of cancer to increasing fat oxidation and reducing LDL (bad) cholesterol. To the claim involving cancer, the FDA basically shut that down ((http://www.cfsan.fda.gov/~dms/qhc-gtea.html)).
Since we’re more concerned with Green Tea’s ability to aid in weight loss, that’s what we’ll discuss. One study done measured the effectiveness of green tea on weight loss in obese Thais ((Physiol Behav. 2007 Oct 18)). The abstract, in its entirety, is quoted below (our own emphasis added):
This study was undertaken to investigate the effects of green tea on weight reduction in obese Thais. A randomized, controlled trial involving 60 obese subjects (body mass index, BMI > 25kg/m(2)) was conducted. All subjects consumed a Thai diet containing 3 meals (8373.6kJ/day) for 12weeks, prepared by the Nutritional Unit at Srinagarind Hospital. The diet contained 65% carbohydrates, 15% protein, and 20% fat. Body weight, BMI, body composition, resting energy expenditure, and substrate oxidation were measured at baseline, and during weeks 4, 8, and 12 of the study. Serum levels of leptin and urine VMA were measured at baseline and during the 12th week. Differences over time and between the treatments (green tea or placebo) over time were determined using two-factor ANOVA with repeated measures. In comparing the two groups, differences in weight loss were 2.70, 5.10, and 3.3kg during the 4th, 8th, and 12th weeks of the study, respectively. At the 8th and 12th weeks of the study, body weight loss was significantly different (P < 0.05). At the 8th week, the difference in resting energy expenditure was 183.38kJ/day (P < 0.001), the difference in the respiratory quotient was 0.02 (P < 0.05), and no significant differences existed in satiety score, food intake, or physical activity. Urine VMA was significantly different in the 12th week of the study (P < 0.05). We conclude that green tea can reduce body weight in obese Thai subjects by increasing energy expenditure and fat oxidation.
Note that the difference from the green tea group to the placebo group by the end of 12 weeks was 3.3kg, or 7.26 pounds. So when you’re looking at a diet pill whose main ingredient is green tea, and they start making claims about losing a pound a day or something like that, you probably want to look elsewhere. Also noted is the fact that the dosage was not given in the study (or I overlooked it).
Another study done by Boschmann and Thielecke found the following ((J Am Coll Nutr. 2007 Aug;26(4):389S-395S)):
The development of obesity is characterized by an increase in adipose tissue mass and by concomitant and profound changes in almost all organ functions leading to diseases such as hypertension, diabetes mellitus and coronary heart disease. Recent data from human studies indicate that the consumption of green tea and green tea extracts may help reduce body weight, mainly body fat, by increasing postprandial thermogenesis and fat oxidation. However, human studies investigating the metabolic effects of the most predominant tea catechin, EGCG, alone are absent. METHODS: In a randomized double blind, placebo-controlled, cross-over pilot study, six overweight men were given 300 mg EGCG/d for 2d. Fasting and postprandial changes in energy expenditure (EE) and substrate oxidation were assessed. RESULTS: Resting EE did not differ significantly between EGCG and placebo treatments, although during the first postprandial monitoring phase, respiratory quotient (RQ) values were significantly lower with EGCG compared to the placebo. CONCLUSIONS: These findings suggest that EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea. However, more studies with a greater sample size and a broader range of age and BMI are needed to define the optimum dose.
Our emphasis was added again. Green Tea’s most abundant catechin is epigallocatechin gallate (EGCG) is commonly found in diet pills — probably 90% of the time.
In another paper done by Wolfram ((J Am Coll Nutr. 2007 Aug;26(4):373S-388S)), the following conclusion is made:
Dose-response relationships observed in several epidemiological studies have indicated that pronounced cardiovascular and metabolic health benefits can be obtained by regular consumption of 5-6 or more cups of green tea per day.
Green Tea is an effective weight loss agent, just watch diet pill company claims to make sure they are in line with studies that have been published.