Nourishing means adding lipids to the skin and hair. Lipids are the 'fats' found in oils and vegetable butters such as shea and coconut oil, and skin that no longer secretes fat (sebum) loses its protective barrier and lacks oxygen. But there is good news: sebum can be replenished through diet, and through nourishing, superfatting and lipid-replenishing treatments. As with oils, these products are the ideal texture to nourish the skin, thanks to formulae enriched with ceramides and other nutrients. Skin that lacks lipids can become rough, damaged, dull and fragile, and it's also more prone to wrinkles and fine lines. Dry skins are the ones that really need to be nourished. Our advice? Night-time is the right time for adding lipids to the skin, in the form of an enriching night cream, and boosting cell renewal.