The use in cosmetics of expanded solid compositions whose matrix contains an alveolar network made from a natural product or from a derivative of a natural product capable of being expanded. These compositions constitute novel galenic forms for cosmetic or dermatological use. These compositions may be in the form of rolls, pellets, sheets or flakes which are expanded or in the form of powder. When reduced to a powdered state, these compositions can also be rehydrated or employed as a pulverulent phase in make-up compositions, in particular, in compacted make-up powders.