Green Tea and Weight Loss in Overweight and Obese Adults
Obesity has become a growing health issue which is associated with increased risk of chronic diseases such as coronary heart disease, hypertension, type 2 diabetes, osteoarthritis, stroke, sleep apnea, and certain cancers (Auvichayapat et al., 2008; Maki et al., 2009; Nagao et al., 2005). In the United States there are an estimated 72 million overweight or obese adults (as cited in Maki et al., 2009). Currently, the most effective treatment for obesity is a combination of reducing energy intake and increasing energy expenditure, yet the most popular treatment is pharmacotherapy (Auvichayapat et al., 2008, Diepvens, Kovacs, Nijs, Vogels, & Westerterp-Plantenga, 2005). Recently, researchers have found antiobesity effects in green tea (Maki et al., 2009). The objective of this term paper is to depict the claim of green tea and its effectiveness on weight loss in overweight and obese adults. Review of the Literature
Overweight and Obese and Weight Loss
The basic reasoning of overweight and obese individuals is an imbalance between energy consumption and energy expenditure (Diepvens et al., 2005). To achieve weight loss, a negative energy balance must occur and can be achieved by decreased energy consumption or increased energy expenditure (Auvichayapat et al., 2008; Diepvens et al., 2005). Genetics may also be linked to obesity in several ways. Genetics may be associated with susceptibility to fat storing and the controllability of food intake (as cited in Shepherd, 2009). It has been inferred that green tea may reduce body weight and increase satiety which will positively effect body composition (Auvichayapat et al., 2008; Diepvens et al., 2005; Maki et al, 2008; Nagao et al., 2005).
Components of Green Tea
Green tea contains two major active ingredients which may be contributed to combating obesity: catechin and caffeine (Auvichayapat et al., 2008; Diepvens et al., 2005). Research has suggested that green tea catechins block the enzyme catechol O-methyltransferase, thereby stimulating the sympathetic nervous system (Auvichayapat et al., 2008; Belza et al., 2009). The stimulation of the sympathetic nervous system may be responsible for increased thermogenesis, fat oxidation and satiety (Auvichayapat et al., 2008; Belza et al., 2009). Green tea catechins may also contribute to increased antioxidant, antiviral, antiplaque-forming, anticancer activities, and decreased blood pressure and total cholesterol (as cited in Nagao et al., 2005). Research has suggested that caffeine may promote thermogenesis and fat oxidation that positively affect body composition (Auvichayapat et al., 2008; Belza et al., 2009; Diepvens et al., 2005). Caffeine obstructs the degeneration of intracellular cyclic adenosine monophosphate, leading to increased norepinephrine release (Auvichayapat et al., 2008). The increased norepinephrine may lead to thermogenesis and may enhance satiety (Auvichayapat et al., 2008). Effects of Catechin and Caffeine Supplementation on Overweight and Obese Adults
Maki et al. (2009) conducted a study to investigate whether green tea catechin intake increased exercise-induced abdominal adiposity loss in overweight and obese adults in the United States. The researchers supported previous claims of green tea catechins’ positive effect on general weight loss, but further investigation was needed to conclude that green tea catechin consumption has a positive effect on body composition and abdominal adiposity.
The study was a randomized, double-blind, controlled clinical trial that took place in two clinical research sites – Bloomington, Indiana and St. Petersburg, Florida. The male and female participants were of good general health and sedentary. The participants were between the ages of 21 and 65, had a waist circumference of 87 centimeters or greater (women) or 90 centimeters or greater (men), and a total cholesterol of 5.2...
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