I've heard of white kidney bean extract, but I've never tried it. I googled it and of course a million things popped up. This is what one site said
"Normally, when you eat carbs, your body digests it as sugar which goes straight into your bloodstream and gets deposited as fat. However, White Kidney Bean Extract, has been shown to prevent the stomach from breaking carbs down into simple sugars — so their calories aren't absorbed into your body."