Antioxidants in green tea could help increase metabolic rate and lean body mass. While green tea is a healthy beverage on its own, the antioxidants get partially degraded in the body, so you lose some of those benefits when the tea is weakened in this process.
How the heck is a thigh gap luscious? All my life I wanted my legs to be less skinny... Getting fit is great, but doing it just to achieve a certain ideal look is not so good. Be happy with what you have and do exercise to be healthy and strong!