http://biblehub.com/commentaries/guzik/revelation/22.htmi.

Some people wonder if we will eat in heaven. The best answer is that we can eat, but will not have to. In His resurrection body, Jesus enjoyed food (Luke 24:41-43, John 21:12-14). Angels ate with Abraham (Genesis 18:6-8). The great heavenly reunion between Jesus and His people is described as a marriage supper (Revelation 19:9). Even though man fell by what he ate, God will still allow us to eat in heaven.

As far as sex, here is a quote from C.S. Lewis

“The letter and spirit of scripture, and of all Christianity, forbid us to suppose that life in the New Creation will be a sexual life; and this reduces our imagination to the withering alternatives either of bodies which are hardly recognizable as human bodies at all or else of a perpetual fast. As regards to the fast, I think our present outlook might be that of a small boy who, on being told that the sexual act was the highest bodily pleasure, should immediately ask whether you ate chocolates at the same time. On receiving the answer ‘No,’ he might regard [the] absence of chocolates as the chief characteristic of sexuality. In vain would you tell him that the reason why lovers in their raptures don’t bother about chocolates is that they have something better to think of. The boy knows chocolate: he does not know the positive thing that excludes it. We are in the same position. We know the sexual life; we do not know, except in glimpses, the other thing which, in Heaven, will leave no room for it.”