I love Jesus and respect his word--he is my Lord and his word is my authority. i have pondered it too. First of all, Jesus' allusion to "I am the bread of life" is a metaphor utilizing the culture of his day. He was saying, "I am your main sustenance, the staple of your life, the essential thing you need." If he had lived in Honduras, it probably would have been "I am the tortilla of life." If he lived in a paleo-eating culture, it probably would have been "I am the grass-fed beef of life" (the best of the best, the most essential).
More "troubling" is GOd's giving the Israelites manna in the wilderness, which appears to be some type of bread. But we don't really know what it was; it was certainly not the typical grain. God provided bread to Elijah via ravens--perhaps he was respecting thier culture; Elijah, culturally, was raised on some bread and that was for him a staple and what he wanted. Was the bread bad for him? SHould God have given him green veggies instead? I don't know. But also, I think even in those days they ate less carbs than our SAD, carb-rich, processed foods diet. Many argue they prepared them differently, sprouting them etc. (sprouted grains is what Ezekiel ate in his bread). Also, I have heard that the quality of our grains is vastly different through breeding, pesticides, GMOs, modificaiton of the sugar and protein content, etc. So, maybe back then they still ate low-carb but also better prepared and healthier grains.
Just some thoughts. But thanks for really thinking about what Jesus says.