Hi Zhao,
Eating, for most people (myself included), is probably usually associated with sensual desire. However, it need not be - for instance, there are some extremely disgusting things you could eat out there. The Bodhisatta and other ascetics apparently feasted on cow feces, and then on their own urine and feces for as long as they could. Do you think there is sensual desire and/or pleasure there? God I would hope not!
Oh and Have you ever read the Puttamamsa Sutta ( SN 12.63 ) :
"“And how, bhikkhus, should the nutriment edible food be seen? Suppose a couple, husband and wife, had taken limited provisions and were travelling through a desert. They have with them their only son, dear and beloved. Then, in the middle of the desert, their limited provisions would be used up and exhausted, while the rest of the desert remains to be crossed. The husband and wife would think: ‘Our limited provisions have been used up and exhausted, while the rest of this desert remains to be crossed. Let us kill our only son, dear and beloved, and prepare dried and spiced meat. By eating our son’s flesh we can cross the rest of this desert. Let not all three of us perish!’
“Then, bhikkhus, the husband and wife would kill their only son, dear and beloved, prepare dried and spiced meat, and by eating their son’s flesh they would cross the rest of the desert. While they are eating their son’s flesh, they would beat their breasts and cry: ‘Where are you, our only son? Where are you, our only son?’
“What do you think, bhikkhus? Would they eat that food for amusement or for enjoyment or for the sake of physical beauty and attractiveness?”
“No, venerable sir.”
“Wouldn’t they eat that food only for the sake of crossing the desert?”
“Yes, venerable sir.”
Extremely gruesome simile. The Buddha seemed to recognize the need to consume food, as well as the inherent danger. Mind you, I don’t think I have ever eaten a single meal in my whole life with the kind of attitude advocated for above!
Regarding sexuality - in the Bhikkhuni sutta ( (AN 4.159 ) we find Ananda speaking to a sick Bhikkhuni:
"This body, sister, comes into being through food. And yet it is by relying on food that food is to be abandoned.
"This body comes into being through craving. And yet it is by relying on craving that craving is to be abandoned.
"This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.
"This body comes into being through sexual intercourse. Sexual intercourse is to be abandoned. With regard to sexual intercourse, the Buddha declares the cutting off of the bridge.
This seems to directly address some of the points you were raising.
Respectfully,
Brad