Paul is arguing against fornication. His argument is that there is a law of adaptation running through nature, illustrated by the mutual adaptation of food and the digestive organs; but this law is violated by the prostitution of the body to fornication, for which, in God's order, it was not adapted.
Shall destroy (καταργήσει)
Rev., better, shall bring to nought. See on Rom 3:3. The mutual physical adaptation is only temporary, as the body and its nourishment are alike perishable.