An object of the present invention is to provide a lipase activity inhibitor that shows high inhibitory activity against pancreatic lipase to suppress the absorption of meal-derived fat and/or which contributes to suppressing and preventing obesity, as well as a food or beverage that has such lipase activity inhibitor incorporated therein. Another object of the invention is to provide a lipase inhibitor of tea origin that suits most consumers' taste and which will not impair the flavor of the food or beverage when incorporated therein. Still another object of the invention is to provide a process for producing said lipase inhibitors. Further object of the invention is to provide antioxidants. To attain these objects, epigallocatechin dimers (oolong homobisflavans) or trimers are incorporated in foods or beverages. As a result, the absorption of meal-derived fat can be suppressed and, in addition, antioxidation effect is obtained. The compounds of the invention can be produced by reacting epigallocatechin gallate with formaldehyde in the presence of an acid.