Objection 1. It would seem that they will rise again to the animal life, or in other words that they will make use of the acts of the nutritive and generative powers. For our resurrection will be conformed to Christ's. But Christ is said to have ate after His resurrection (John 21; Luke 24). Therefore, after the resurrection men will eat, and in like manner beget.
Objection 2. Further, the distinction of sexes is directed to generation; and in like manner the instruments which serve the nutritive power are directed to eating. Now man will rise again with all these. Therefore he will exercise the acts of the generative and nutritive powers.
Objection 3. Further, the whole man will be beatified both in soul and in body. Now beatitude or happiness, according to the Philosopher (Ethic. i, 7), consists in a perfect operation. Therefore it must needs be that all the powers of the soul and all the members should have their respective acts after the resurrection. And so the same conclusion follows as above.
Objection 4. Further, after the resurrection there will be perfect joy in the blessed. Now such a joy includes all pleasures, since "happiness" according to Boethius is "a state rendered perfect by the accumulation of all goods" (De Consol. iii), and the perfect is that which lacks nothing. Since then there is much pleasure in the act of the generative and nutritive powers it would seem that such acts belonging to animal life will be in the blessed, and much more in others, who will have less spiritual bodies.
On the contrary, It is written (Matthew 22:30): "In the resurrection they shall neither marry nor be married."
Further, generation is directed to supply the defect resulting from death, and to the multiplication of the human race: and eating is directed to make up for waste, and to increase quantity. But in the state of the resurrection the human race will already have the number of individuals preordained by God, since generation will continue up to that point. In like manner each man will rise again in due quantity; neither will death be any more, nor any waste affect the parts of man. Therefore the acts of the generative and nutritive powers would be void of purpose.
I answer that, The resurrection will not be necessary to man on account of his primary perfection, which consists in the integrity of those things that belong to his nature, since man can attain to this in his present state of life by the action of natural causes; but the necessity of the resurrection regards the attainment of his ultimate perfection, which consists in his reaching his ultimate end. Consequently those natural operations which are directed to cause or preserve the primary perfection of human nature will not be in the resurrection: such are the actions of the animal life in man, the action of the elements on one another, and the movement of the heavens; wherefore all these will cease at the resurrection. And since to eat, drink, sleep, beget, pertain to the animal life, being directed to the primary perfection of nature, it follows that they will not be in the resurrection.
Reply to Objection 1. When Christ partook of that meal, His eating was an act, not of necessity as though human nature needed food after the resurrection, but of power, so as to prove that He had resumed the true human nature which He had in that state wherein He ate and drank with His disciples. There will be no need of such proof at the general resurrection, since it will be evident to all. Hence Christ is said to have ate by dispensation in the sense in which lawyers say that a "dispensation is a relaxation of the general law": because Christ made an exception to that which is common to those who rise again (namely not to partake of food) for the aforesaid motive. Hence the argument does not prove.
Reply to Objection 2. The distinction of sexes and the difference of members will be for the restoration of the perfection of human nature both in the species and in the individual. Hence it does not follow that they are without purpose, although they lack their animal operations.
Reply to Objection 3. The aforesaid operations do not belong to man as man, as also the Philosopher states (Ethic. x, 7), wherefore the happiness of the human body does not consist therein. But the human body will be glorified by an overflow from the reason whereby man is man, inasmuch as the body will be subject to reason.
Reply to Objection 4. As the Philosopher says (Ethic. vii, 12, x, 5), the pleasures of the body are medicinal, because they are applied to man for the removal of weariness; or again, they are unhealthy, in so far as man indulges in those pleasures inordinately, as though they were real pleasures: just as a man whose taste is vitiated delights in things which are not delightful to the healthy. Consequently it does not follow that such pleasures as these belong to the perfection of beatitude, as the Jews and Turks maintain, and certain heretics known as the Chiliasts asserted; who, moreover, according to the Philosopher's teaching, would seem to have an unhealthy appetite, since according to him none but spiritual pleasures are pleasures simply, and to be sought for their own sake: wherefore these alone are requisite for beatitude.
Source: Summa Theologica (New Advent)