Best Kept Secrets To Healthy Aging – Green Tea

In men and women, the degree of body fat, whether expressed as percent body fat or the ratio of waist circumference to hip circumference, tends to decrease as green tea intake increases. Green tea contributes to the maintenance of healthy body weight in several ways.

One of the least appreciated properties of green tea is its ability to limit the absorption of the fat taken in from the diet. Green tea catechins (especially EGCG) interfere with the lipase (fat-digesting) enzymes in the stomach and small intestine. The resulting incomplete digestion of fats produces some lipid droplets that are not able to enter intestinal cells and that therefore remain unabsorbed. These effects have produced significant decreases in the absorption of dietary fats by rats consuming green tea. While it is not known how effective green tea is in blocking fat absorption in humans, any interference with the normally highly efficient digestion and absorption of dietary fats could figure prominently in any effort to manage weight effectively.

Green tea catechins not only decrease the efficiency of absorption of fatty acids from the diet, they also interfere with the production of fat for storage in adipose tissue depots. Green tea leaf extract that is both purified and rich in EGCG decreases the activity of fatty acid synthase, which is an enzyme that regulates how quickly the body produces fat for storage. This process is consistent with a body of literature recently analyzed in the journal Molecular Nutrition and Food Research, which shows how EGCG inhibits new fat formation – “lipogenesis” – and fat storage within adipocytes. Tea aids in the absorption of less fat from the diet, and can also interfere directly with the storage of fat in adipocytes, a dual mechanism for supporting healthy body weight.

EGCG, the dominant green tea catechin, allures the body to change some of its ways of producing energy from glucose-burning to fat-burning. There are two different ways of doing this, and EGCG appears to do both. The first way, is if the amount of glucose available to tissues (especially the skeletal muscles) is reduced, then additional fat must be metabolized to carbon dioxide and water in order to satisfy energy needs. When there is a shorter supply of glucose, the liver is able to synthesize glucose from a wide array of precursors, such as amino acids that are released by muscle cells. The primary enzyme in this synthetic, gluconeogenic pathway, is phosphoenolpyruvate carboxykinase (PEPCK), which is inhibited by EGCG. The blockage of this enzyme reduces the formation rate of new glucose, requiring cells to switch to fat-burning for a source of energy.

In one example of interesting biochemical coordination, EGCG stimulates the conversion of fatty acids to energy. According to cell culture studies, EGCG, rather than glucose, is able to raise the rate of utilization of fatty acid breakdown products in order to produce energy. Since mice are often studied because they obtain energy similarly to the way humans do, they were used in a series of experiments. In these experiments, they responded to the addition of catechin-rich green tea extract to a high-fat diet but not fed catechins, even though they ate just as much. In a recent study of dietary supplementation, mice exercised with tea catechins forced skeletal muscles to move from using their glycogen reserves as sources of energy to increase their dependency on burning fats from adipose depots. Being that this move is very reproducible, the researchers are able to predict when it will happen. Phytonutrients – catechins – in green tea and green tea extract are so powerful, that they are able to recruit muscles to help stored fat get used up faster!

Thermogenesis, in humans. In one example of the fat-burning, thermogenic effects of green tea catechins, 24 hour heat production was calculated in slender healthy to overweight young men during times at which they were in a state of rest and consumed identical diets; they did not consume caffeine-containing foods or beverages, but they did intake either a placebo, 150 mg of caffeine alone or 150 mg of caffeine plus 270 mg of EGCG and 105 mg of other mixed catechins. Researchers observed that the intake of placebo or 150 mg of supplemental caffeine during a 12 hour period did not affect the utilization of glucose or fat in order to supply energy. However, the consumption of green tea catechins during a 12 hour period increased total energy expenditure and heat production in the same-day 24 hour period. It was found that increased fat-burning and decreased use of glucose for fuel caused this energy usage.

Because under the conditions of this experiment all energy expenditure was essentially “resting” energy expenditure, the catechin-induced increase in resting energy expenditure reflects enhanced thermogenesis. That is, more heat production as a “byproduct” of energy production. Since increased heat production to satisfy the same energy demand means that the efficiency of energy production decreased, more stored energy needed to be “burned” – accelerating the rate at which energy stored in fat depots would become depleted. Of course, as stored fat becomes depleted, both body weight and fat depot size decrease. The increase in fat utilization in this experiment, which was minimized by keeping the subjects in a “resting” state, could result in the loss of one pound of excess body weight in 1 to 2 months and a loss of 6 to 12 pounds in a year. Consistent with this rough prediction, overweight adults consuming 270 mg of EGCG daily for 3 months experienced an average loss of 4.6% of total body weight, with an average decrease in waist circumference of 4.5%. This thermogenic effect of green tea catechins, when combined with a healthy diet and exercise, could be extremely beneficial for those looking to support weight management efforts.

Beneficial results were also shown in a gold standard, randomized placebo-controlled clinical trial, which was published recently in the American Journal of Clinical Nutrition. During this study, healthy men added either 22 mg or 690 mg of catechins daily to their diets for a total of 12 weeks. The results of this experiment showed that the men who were consuming 690 mg of catechins every day had lost more weight, inches off their waist, total body and abdominal fat.

What about Stress and Abdominal Fat?

A growing body of evidence indicates that in both men and women, stress and mood issues are associated with increased abdominal fat storage and a larger waistline. How is stress and belly fat connected? Stress can increase the secretion of a hormone called cortisol. This hormone increases the rate of fat accumulation by abdominal fat cells. Even among healthy individuals, repeated episodes of stress-related cortisol secretion is implicated in increased abdominal fat.

What Can Green Tea Do About It?

Green tea contains an unusual amino acid – L-theanine. This amino acid comprises up to 2.5% of the total dry weight of unfermented green tea leaves, is absorbed efficiently and can enter the brain from the blood. Within the brain, L-theanine exerts relaxing physiologic effects. In so doing, L-theanine may act to reduce perceptions of stress with possible beneficial effects on abdominal fat formation. For example, mice fed L-theanine have gained less weight and accumulated less abdominal fat. By supporting the body’s stress response, green tea and green tea extracts containing L-theanine can make important contributions to healthy weight maintenance.

Joe Singleton has been in the vitamin and nutrition industry for over 20 years helping people understand the value of healthy aging. To read more, please check out the Purity Products website.

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