Garcinia cambogia is a fruit grown across India and Southeast Asia and it is used there as a food and its rinds are used in some traditional recipes of south India. It used to be an obscure hard-to-find ingredient, but recently the Internet has exploded with websites selling weight loss products based on an extract of the fruit and it even got some decidedly hucksterish treatment from Dr.
Oz, a TV personality made famous by Oprah Winfrey. The fruit is known in India as gambooge. It is apparently also an ingredient in some weight loss products as hydroxycitric acid.