green tea has EGCG which can help in weight loss, but
Oolong is more for weight loss and is also known to block carbs.
Mate is good for curbing appetite, but has the same caffeine as coffee.
If you are worried about caffeine drink white tea, it has 1-2% of the caffeine of a cup of coffee and is great for skin and hydration, green has 5-10%, oolong more, black more, mate most.
Or herbal or rooibos! they have no caffeine :w00t:
I work at a tea parlor.