Is your hair on a diet? Weightless styling products are especially beneficial to those who do not wash their hair daily. These products produce less build-up than traditional styling products, which can leave hair greasy, oily, flat and lifeless. Primers are popular skin care and makeup products, but this is one of the first examples of “primer” for hair. Living Proof’s Prime Style Extender promises to “protect and extend the life of your style twice as long.” This column will review the ingredient listing for functionality and claims substantiation.