Tea before exercise burn 17% more fat?

Research indicates that the researchers to twelve people as objects, as allowed thirty minutes during continuous cycling like intensity based before exercise, intake of catechins with placebo were found to increase the intake of catechin group than in the placebo group, 17% of energy consumption from fat.

Exercise will stimulate the body's secretion of norepinephrine induced lipolysis enzyme process, which convert fat into energy, it can Cellulite, yet another human COMT enzyme breaks down norepinephrine, make fat metabolism are affected, catechins can inhibit COMT effect just enhance fat burning efficiency.

One of the roles of adrenaline is to promote the release of glucose from the locations in the body where it's stored. If catechins can inhibit COMT effect, it helps to burn more energy from fat during exercise.

I would like to know on which part of body's fat would be converted into energy under this situation, on the other words, where do this process converting fat into energy take place? and where do the fat come mainly from?

Does anyone have any suggestions?
Thanks in advance for any suggestions