Interesting issue. Definitely some to think about.Further, I would surmise that the Amish are probably quite a bit more active in their everyday activities, which probably has a huge impact on overall health.
Some biochemists and personal trainers suggest that diet trumps activities in terms of body composition/health etc. I realize it is up for debate, but in my experience changing my diet and exercising has done more for me than just exercising. If I am only exercising but I am eating crap, the food I eat can cancel out the benefits of the exercise.
Some of the above so diet is significantly more important.
Food for thought.