Green tea extract and weight loss

green-tea-1Bioactive substances in green tea boost the effect of hormones that signal your body to liberate fat cells from storage and burn them for fuel.

Also rich in antioxidants that protect against oxidative damage, green tea is billed as one of the healthiest beverages you can drink.

A cup of tea made from quality leaves delivers a range of beneficial compounds within 30 – 60 minutes (1), initiating changes in hormone balance, taming free radical activity, and providing mild stimulation through caffeine.

While the caffeine content of green tea is lower than coffee by about 75%, it’s enough to make a difference, and several studies indicate caffeine can play an important role in regulating body weight.

A common ingredient in weight-loss supplements, caffeine may suppress appetite, but too much can disturb sleep patterns. Sleeping less than five hours a night is associated with weight gain (2), so the lower caffeine content in tea could work in your favor for dropping extra body fat.

Several studies confirm that caffeine enhances athletic performance, as well as ramping up fat-burning processes in the body. (3, 4)

The abundance of antioxidants called catechins found in green tea sets it apart from other drinks, making it a super-healthy choice with benefits across the board. (5) Recent research indicates antioxidants may also slow down the production of triglycerides at a cellular level through inhibiting enzymes necessary for this process. (6)

For weight loss, the most important of these catechins is epigallocatechin gallate (EGCG), which revs up metabolism. Let’s take a look at how that works.

Catechins: Working to Help You Burn Fat

Stored fat must be discharged from cells and enter the blood stream before it can be burned for fuel. Green tea’s active compounds enhance the effect of hormones required for releasing fat from cells.

The hormone norepinephrine acts like a messenger, carrying signals from the central nervous system to fat cells, instructing them to break down fat so it can be released.

Epigallocatechin gallate, the star player in green tea’s catechin cast, is especially proficient at inhibiting the enzyme that breaks down norepinephrine. This is important because when EGCG slows this process down, the body ends up with a greater concentration of norepinephrine in circulation. (7)

When there’s more norepinephrine cruising through the system, more messages to break down stored fat and set it free are delivered to the cells. The end result is more fat can be accessed for energetic requirements. (8)

Caffeine also appears to interact with EGCG synergistically in the process of liberating stored fat from cells, utilizing the same hormonal pathway traveled by signals sent from the central nervous system. (9)

Thermogenic Properties Enhance Long Term Weight Loss

The body can draw from energy in stored fat to meet fuel needs during periods of strenuous exertion, like when you’re pedaling up a big hill, or covering the second half of your jogging route.

Green tea helps you burn even more fat during intense exercise. Male subjects who took green tea extract burned up to 17% more fat during exercise periods than those who didn’t. (10)

Energy demands are constant, and cellular functions require fuel whether you’re sitting, lying on the couch, or sleeping. The thermogenic properties of green tea can actually extend around the clock, affecting metabolism even when you’re not active.

Conclusions from most studies indicate green tea extract increases energy consumption at rates between 3% and 4%, while others measured up to 8%. (11, 12, 13) Obviously the effects differ between individuals, but even with the lower percentages, someone eating about 2000 calories a day would burn 60 to 80 more calories over 24 hours. (14)

Several studies support the evidence that EGCG in green tea enhances the body’s capacity to burn more fat at rest, which can have a significant effect on achieving lower body fat percentages and maintaining the changes over time. (15, 16, 17)

A clinical trial with 60 obese participants showed promising results for weight loss over a three-month period. Not only did the subjects drop an average of just over 7 pounds, but energy expenditures rose during the trial. At the finish line, participants were burning an average of 183 more calories daily than when they began. (18)

While animal studies indicate the compounds in green tea may inhibit fat absorption during digestion (19, 20), this effect has not yet been proven with humans.

When it comes to appetite, studies show conflicting results, so the main documented benefit in regard to dropping extra pounds is rooted in the positive effect of green tea on metabolism. (21)

Selective Fat Loss Drops the Risk of Serious Disorders

The fat loss experienced by most subjects participating in the studies mentioned above was not dramatic, sometimes only amounting to 3 or 4 pounds. (22, 23)

However, it’s important to remember not all fat has the same effect on health, and significant percentages of the fat reduction noted in studies involving green tea extract came from abdominal deposits. (24, 25)

This visceral fat stored around organs and tucked away in the midsection is the most dangerous type.

Negatively affecting insulin resistance and triggering inflammation, deep fat is linked to higher risk factors for metabolic disorders, including type 2 diabetes. (26)

The chances of suffering a heart attack go up when you carry excess abdominal fat (27), and inflammation is associated with a staggering list of disorders ranging from gastrointestinal diseases to arthritis.

Women with generous stores of visceral fat are more likely to need gallbladder surgery, as well as be diagnosed with breast cancer. (28)

Recap

While incorporating green tea may not always produce fast or steady weight loss, the package of beneficial effects on metabolism make it a worthwhile strategy to include in weight management and overall health programs.

If you don’t care for the taste of green tea, supplements are available that have the same effect as drinking it; most of the studies mentioned above were done with participants taking encapsulated formulas.

Summary: Green tea bumps up metabolism around the clock, triggers hormonal processes necessary for releasing stored fat, targets the most dangerous fat storage areas, and adds antioxidants to help prevent health issues that may compromise your ability to achieve and maintain normal body weight.

Resources:

  1. http://www.tandfonline.com/doi/abs/10.1207/S15327914NC340112
  2. http://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/sleep-and-weight-gain/faq-20058198
  3. http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2005.00445.x/abstract
  4. http://ajcn.nutrition.org/content/79/1/40.full.pdf+html
  5. http://www.tandfonline.com/doi/abs/10.1080/07315724.2006.10719518
  6. http://www.webmd.com/diet/20071102/antioxidants-may-fight-fat
  7. http://dmd.aspetjournals.org/content/31/5/572.short
  8. http://www.sciencedirect.com/science/article/pii/S0031938410000703
  9. http://www.nature.com/ijo/journal/v24/n2/full/0801101a.html
  10. http://www.ncbi.nlm.nih.gov/pubmed/18326618
  11. http://www.ncbi.nlm.nih.gov/pubmed/10584049
  12. http://www.ncbi.nlm.nih.gov/pubmed/16176615
  13. http://www.ncbi.nlm.nih.gov/pubmed/17299107
  14. http://www.ncbi.nlm.nih.gov/pubmed/17882140
  15. http://jhs.pharm.or.jp/data/51(2)/51_233.pdf
  16. http://www.ncbi.nlm.nih.gov/pubmed/17906192
  17. http://www.ncbi.nlm.nih.gov/pubmed/20372175
  18. http://www.ncbi.nlm.nih.gov/pubmed/18006026
  19. http://www.ncbi.nlm.nih.gov/pubmed/15738931
  20. http://www.ncbi.nlm.nih.gov/pubmed/15539342
  21. http://www.sciencedirect.com/science/article/pii/S0955286310001609
  22. http://www.ncbi.nlm.nih.gov/pubmed/19597519
  23. http://www.ncbi.nlm.nih.gov/pubmed/19906797
  24. http://jn.nutrition.org/content/139/2/264.full
  25. http://www.sciencedirect.com/science/article/pii/S1756464611001162
  26. http://ajcn.nutrition.org/content/87/5/1118.full
  27. http://www.ncbi.nlm.nih.gov/pubmed/17667865
  28. http://www.health.harvard.edu/staying-healthy/abdominal-fat-and-what-to-do-about-it

 

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