Ubee - I think nature provides us many answers but I think the best answer we've ever been given for weight loss is move more, eat less.
And companies do invest in natural remedies when they do work such as a big company (can't remember who now) bought out the rights to exclusively use hoodia in their products because it was something that worked in it's natural leafy state. The problem is that they couldn't replicate the appetite suppressant effects out of its natural state despite trying for years. That didn't stop other diet companies from claiming they contained hoodia or marketing it. Green tea was also something to shown to have a slight effect in tea form but never in pill form but doesn't stop diet pill companies from marketing it based on studies of green tea you drink. If you think big pharma is bad, you should see the diet industry, it is the worst which is why I'd be more wary of any diet pills than any big pharma medicine.
You can't out-exercise poor eating habits.