I am trying to remember the name of these under garment things that Oprah was talking about not too long ago. Basically it is something that makes you look thinner and you wear under your clothes

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I have a wedding I am in the end of this month and I have gained a few pounds and would like to use this product but I can not for the life of me remember what they are called. I know it is some type of spandex thing.
Can any one help me remember?