How much should a 21 year old woman eat between 7am and 4pm? (before dinner?)?

My girlfriend has tried everything to lose weight but nothing has worked just as effectively as the wu yi tea that she drinks, it's been covered on CNN and Fox News. She lost 8 pounds in three weeks. She buys it off a contact at work but I discovered this site in Google; www.Wu-YiNow.com - they have a free trial on at the moment, maybe they're worth a try?