The actions of PPARβ/δ in skeletal muscle,that is, oxidative myofiber remodeling and increase of fatty acidburning capacity, may explain the beneficial effects of specificagonists on obesity and insulin resistance by limiting substrateavailability for lipid synthesis and accumulation in adiposetissue and other insulin sensitive tissues. The gene discussed is PPARD; the disease is obesity due to melanocortin 4 receptor deficiency.