He had no appetite because of the heat.
He is under the weather because of the heat.
He could not sleep because of the heat.
He has a fever because of his cold.
He has little appetite for lack of exercise.
He wants the bare necessaries of life, to say nothing of luxuries.
He was on the point of dying from cold and hunger.
He still can't even eat.
He's not picky about what he eats.