Tripe, tongue and liver might not show up on your grocery list very often, but the cuts of meat come from the same animals that provide steaks and bacon. The organ meats, often called offal, are much less common in the Western diet. But some researchers think this could be the opportunity for offal to make a comeback of sorts. As global meat consumption continues to rise, concerns about the sustainability of raising and slaughtering enough livestock to meet demand have led some scientists to question whether eating, well, more of an animal could reduce its environmental impact.