For health reasons, returning to traditional, local diets is a smart move. However, it ultimately does not solve the food crises. Eating less red meat and more fish moves the problem to a different arena, and our oceans are arguably less able to take the additional stress then our lands. Traditional diets were sustainable when the demand for food was much more in line with the capacity of the environment to provide. however, now that humans are consuming a huge chunk of the earths net primary production, such traditional diets, and the framing/fishing that supports them, are no longer sustainable in the same way. I am not trying to advocate for our new, corn-based food system, and DO I believe that the diets of our ancestors are a good map to follow, it's just that civilization is moving forward, and I don't think going back to what worked in the past is a recipe for success now. 

I'm not so positive that the Pope's message was aimed at transsexuals. But, regardless of exactly what he was talking about, the whole analogy between respecting ones own body - the ultimate individual property, and respecting the environment - a common good, is really weak. Controlling what people do with their bodies is a political/moral issue, protecting environmental resources is an issue of long term economics.