“So many people ask me this question. I will write it down one day to explain to the people.

“Not scientifically, as I have not done scientific examinations. What I did was I observed what happened to me and what happened to other people, and I have drawn my own conclusions.

“It is not scientific, not proven and not tested, but this is what I’ve observed in this life,” he said, drawing applause from the participants at a dialogue session at the Asean Business and Investment Summit 2019, which was moderated by Asean Business Advisory Council chairman Arin Jira here today.

Mahathir told participants that he stayed healthy and fit by not overeating.

“First thing is not to overeat. Eat to live, not live to eat. That is very simple.

“When the food is nice, stop eating; that is my mother’s advice to me.

“When the food is tasty, stop eating. It is very difficult but we have to develop that discipline,” he said.

Mahathir advised the audience to avoid taking too much fatty food, carbohydrates and sugar in their diet to stay healthy.

He said to stay healthy, one must stay active and exercise regularly to prevent muscle loss.

“Staying active involves the whole system, not just the muscles. If you use your brain all the time — talk, think, argue, debate, quarrel — it activates the brain and it will be functioning well.

“If it is not functioning well on certain things, do it over and over again. Whatever we do repeatedly, we will remember.

“If after retirement, we rest and sleep, the brain, as well as the body, will lose its capacity,” he said.