Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females

We assessed the effect of ingestion of green tea (GT) extract along with a low-energy diet (LED) on resting energy expenditure (REE), substrate oxidation and body weight as GT has been shown to increase energy expenditure and fat oxidation in the short term in both animals and people. Forty-six overweight women (BMI 27 center dot 6 (sd 1 center dot 8) kg/m(2)) were fed in energy balance from day 1 to day 3, followed by a LED with GT (1125 mg tea catechins +225 mg caffeine/d) or placebo (PLAC) from day 4 to day 87. Caffeine intake was standardised to 300 mg/d. Energy expenditure was measured on days 4 and 32. Reductions in weight (4 center dot 19 (sd 2 center dot 0) kg PLAC, 4 center dot 21 (sd 2 center dot 7) kg GT), BMI, waist:hip ratio, fat mass and fat-free mass were not statistically different between treatments. REE as a function of fat-free mass and fat mass was significantly reduced over 32 d in the PLAC group (P < 0 center dot 05) but not in the GT group. Dietary restraint increased over time (P < 0 center dot 001) in both groups, whereas disinhibition and general hunger decreased (P < 0 center dot 05). The GT group became more hungry over time and less thirsty, and showed increased prospective food consumption compared with PLAC (P < 0 center dot 05). Taken together, the ingestion of GT along with a LED had no additional benefit for any measures of body weight or body composition. Although the decrease in REE as a function of fat-free mass and fat mass was not significant with GT treatment, whereas it was with PLAC treatment, no significant effect of treatment over time was seen, suggesting that a robust limitation of REE reduction during a LED was not achieved by GT.