1. Green Tea & Fat Metabolism MacKenzie Stark Macronutrient Metabolism 12-6-12

2. The Obesity Epidemic  Obesity is currently viewed as one of the most serious health problems of the 21 st century.  Obesity is a medical condition in which an individual has excess body fat in relation to lean body mass.  Defined as having a BMI of 30 or higher.  Associated with T2DM, CVD, hypertension, and certain cancers.

3. Green Tea Components  During the past 10 years, green tea has been studied for its potential as a natural agent for weight loss.  Green tea contains polyphenol components, also known as catechins.  The most abundant catechin in green tea leaves is epigallocatechin gallate (EGCG).  Researchers have proposed that EGCG may have an anti-obesity effect.

4. Fatty Acid Synthesis  Fatty acid synthesis is the creating of fatty acids from acetyl-CoA and malonyl-CoA precursors.  Acetyl-CoA is carboxylated to malonyl-CoA by the enzyme acetyl-CoA carboxylase (ACC).  Malonyl-CoA can then feed into the fatty acid synthase system.  Series of enzymatic reactions occur and the end product is palmitic acid.  Fatty acids are stored as triglycerides in adipose tissue.

5. Acetyl-CoA carboxylation to Malonyl-CoA

6. Fatty Acid Synthase System

7. The Effect of Catechins  The exact mechanism of catechins on fatty acid synthesis is inconclusive.  However, researchers have proposed that catechins have the ability to inhibit the action of ACC.  This would reduce the production of malonyl-CoA.  The reduction in malonyl-CoA would directly decrease fatty acid synthesis  Malonyl-CoA is a highly regulated molecule in fatty acid synthesis, and it inhibits carnitine palmitoyl transferase I.  Relieving inhibition of CPT1 allows more fatty acids to enter the mitochondrial matrix and effectively increases Beta-oxidation of fatty acids.

8. Clinical Trial 1  This study consisted of 30 volunteers-15 were put in the experimental group and 15 in the control group.  Between the ages of 20 and 50, with a BMI greater or equal to 24 kg/m2.  Experimental group consumed two 325 mL of a green tea beverage each day containing 267 mg catechins and 18 g of inulin powder.  Control group consumed two 325 mL of a green tea beverage each day containing 81 mg catechins.  Each group ate three meals provided by the hospital, and all other foods and beverages that contained catechins, polyphenols or caffeine were prohibited.  Study lasted eight weeks, where the first six weeks were the experimental weeks, and the last two weeks were a follow-up period.  Body weight, BMI and fat mass were measured in each group at the third, sixth and eighth week.

9. Results  There was a significant reduction in body weight, BMI and fat mass in the experimental group compared to the control group at the third and sixth week.  These differences were maintained during the two week follow-up period.  The mean BMI in the control group was 26.7 at baseline and remained the same after six weeks.  The mean BMI of the experimental group was 27.3 at baseline and decreased to 26.6 after six weeks.  Results show that catechin-rich green tea plus inulin may have beneficial effects in people who are overweight or obese.

11. Clinical Trial 2  The second study consisted of 240 Japanese men and women with visceral fat-type obesity between the ages of 25 and 55.  The control group received one 340 mL green tea beverage daily with 96.3 mg catechins and 75 mg caffeine.  The experimental group received one 340 mL green tea beverage daily with 582.8 mg catechins and 72.3 mg caffeine.  Dietary intake was not monitored, but food products and/or medications known to influence lipid or CHO metabolism were prohibited.  The study started with a two week run in period and a 12 week treatment period.  Each subject visited the medical institution at four week intervals to have their anthropometrics and biochemical labs recorded.

12. Results  After the 12 week trial, the results showed a significant decrease in body weight, BMI, body fat ratio, body fat mass, waist circumference, and hip circumference in the experimental group.  Lean body mass significantly increased over time.  Total fat area, visceral fat are, and subcutaneous fat area all significantly decreased in the experimental group compared to the control group.  The mean BMI decreased by 0.6 in the experimental group, and there was no change in BMI in the control group after 12 weeks.  Results suggest that continuous ingestion of catechins in high amounts reduces body fat and might prevent obesity.

13. Catechin/c ontrol Week 0Week 4Week 8Week 12 Value at Week 12 * Body weight (kg) † ‡ § Catechin73.3 (9.7)72.5 (9.8)72.2 (9.8)71.6 (9.8)- 1.7 (1.5) Control72.1 (10.0)71.9 (10.1)71.9 (10.2)72.1 (10.3)- 0.1 (1.7) BMI (kg/m 2 ) † ‡ § Catechin26.9 (1.9)26.6 (1.9)26.4 (1.9)26.2 (1.9)- 0.6 (0.6) Control26.7 (2.1)26.6 (2.2) - 0.0 (0.6) Body fat ratio (% ) † ‡ § Catechin30.7 (6.4)30.0 (5.8)28.9 (6.3)28.3 (6.1)- 2.5 (3.3) Control30.7 (5.4)30.2 (5.7)29.2 (5.6)30.0 (5.6)- 0.7 (2.8) Body fat mass (kg) † ‡ § Catechin22.3 (4.6)21.6 (4.0)20.6 (4.1)20.0 (4.0)- 2.3 (2.6) Control22.1 (4.4)21.6 (4.7)20.9 (4.6)21.5 (4.7)- 0.5 (2.3) Lean body mass (kg) ‡ Catechin51.0 (9.4)50.9 (9.3)51.5 (9.8)51.6 (9.7)0.6 (2.3) Control50.1 (8.6)50.3 (8.6)51.0 (8.9)50.5 (8.8)0.4 (2.3) Waist circumference (cm) † ‡ § Catechin87.2 (5.2)86.3 (5.3)85.5 (5.5)84.7 (5.5)- 2.5 (2.2) Control86.5 (6.1)86.4 (6.5)86.6 (6.8)86.5 (6.7)0.0 (2.5) Hip circumference (cm) † ‡ § Catechin98.0 (4.7)97.2 (4.5)96.3 (4.4)95.7 (4.4)- 2.3 (2.0) Control97.2 (5.6)97.0 (5.9)97.1 (6.0) - 0.1 (2.4) Total fat area (cm 2 ) † ‡ § Catechin324.3 (79.3) 308.4 (79.9)- 16.0 (46.6) Control315.8 (77.1) 316.0 (79.0)0.1 (32.6) Visceral fat area (cm 2 ) † ‡ § Catechin109.2 (42.3) 98.9 (38.6)- 10.3 (23.3) Control107.7 (44.0) 103.8 (38.9)- 3.9 (24.9) Subcutaneous fat area (cm 2 ) † § Catechin215.2 (66.9) 209.5 (66.3)- 5.7 (38.5) Control208.1 (60.7) 212.1 (64.9)4.0 (24.8)

14. Discussion  Both studies suggested that green tea catechins ingested in high amounts increase fat loss in overweight or obese individuals.  However, the exact mechanism regarding the effect of catechins on fat metabolism is inconclusive and further studies are needed.  Several limitations to each study. The first study added inulin. Inulin is a naturally occurring soluble fiber. Inulin can give you a feeling of fullness and suppress your appetite. Could this account for the weight loss?  Green tea contains caffeine, which has been studied for its effect on weight loss. Synergy effect?  The dosage of catechins in the experimental groups was very high. Equivalent to 8-10 cups of green tea daily. What’s the best way to ingest high amounts of catechins?

15. Conclusion  Catechins found in green tea appear to aid in the reduction of fat.  Green tea catechins appear to be safe, as no adverse reactions were seen in either study.  A natural and effective supplement that can be used to support weight loss in overweight or obese individuals.

16. Questions?