The Acharanga Sutra narrates a very nice incident about Abhi who was getting very upset about the signs of old age. Look at his case. Change your life-style. Exercise discretion with regard to your diet. Whatever Mahavira has said regarding the health of a child is also applicable for an aged person. What should an aged person eat? The first thing to remember is that as man advances in years, the functioning capacity of his organs diminishes.
If an old person takes indigestible food, he should never think in terms of being healthy. How can a person who eats very heavy food remain healthy? When a person cannot digest even very light food, how would he digest fried and roasted things? If an aged person wishes to be healthy, he should avoid taking heavy food. One should change his food habit after the age of 50 years. As a matter of fact, his food habit should be changed even earlier, when he is 40 years old.