I haven't heard of "wu long," but I did a web search and it appears to be the same as oolong. Please correct me if I'm wrong
I drink a hot mug of oolong, 16 oz, two to three times per week, about an hour or so before bed. I buy loose leaves, infuse them myself, and I'm able to get several infusions from the same leaves (thank goodness, since it's about $25 for two ounces of dry leaves!) The place where I buy my oolong says the type I buy has the lowest caffeine of all their teas, hence the reason for drinking it before bed. They also say it's good for weight loss and cholesterol.
I don't think oolong has had an effect on my weight loss more than any of the other teas I enjoy (rooibos, white, black, green). Unfortunately, I think the marketing folks for tea companies are taking the fact that tea (any kind) is a diuretic and has caffeine and calling it a weight loss product. Don't get me wrong...I LOVE premium loose teas! It's just for every "study" I read about metabolism and tea, I find another that shows the same for coffee or other caffeinated diuretics.
I'll tell ya' what my whole family has noticed with oolong...COMPLEXION! DH and I will drink a mug a few days in a row, and our skin is just glowing -- like expensive facial glowing. It's also cleared up some neverending dermatitis I've dealt with for years that my PCP never could seem to get rid of with prescription creams.
Last week, one of my doggies was suffering from skin allergies from all our oak pollen. She'd just about stopped chewing/licking, but the damage had already been done the week before. We tried bathing her in an oatmeal shampoo recommended by our vet, but her skin still looked horrible even after a few days. I made some oolong for myself, let the leaves completely cool and put a few moist leaves in a napkin and just dabbed the moistened napkin/leaves on her sore spots. They were 50 percent better the next morning. I repeated that evening, and they looked even better the next day.
Sorry to get too far off topic
Anyway, I love good teas for a variety of health/spiritual/relaxation benefits (did I mention temporarily relieving toothache pain?), but I'm just not positive weight loss is one of them.