[rudyfink]

Maybe, in essence, the bacteria that we host to help break down carbs start producing something that makes us crave/prefer carbs?

It seems like the bacteria would, in essence, be self interested and might have developed their own evolutionary mechanism to promote the supply of their food source?

In other words, if we, essentially, keep internal bacteria colonies to help break down specific types of food, those colonies may encourage consumption of their specialized food source?

We may also, symbiotically, encourage the preservation/maintenance of internal processing capability?