LCA first, always. Ecodesigning without LCA means optimising by intuition, with a high risk of choosing the wrong lever (replacing plastic with glass, for example, which often worsens the carbon footprint). LCA identifies the 2-3 sources concentrating 70-80% of the impact, and these are the ones to work on. Ecodesign without LCA is a marketing process, not a technical one.
Read the source article: What is the environmental impact of cosmetics?