President Donald Trump could live up to 200 years if he had maintained a healthier diet over the past 20 years, White House physician, Dr Ronny Jackson, said, adding God gave him “incredible genes”.

Jackson said, while presenting the outcome of Trump’s medical fitness, that the president could eat KFC and McDonald’s and still be in great shape because God gave him ‘incredible genes’.

The White House physician also declared the president as “very healthy” and his overall health “excellent” in spite of his unhealthy habits.

“It’s called genetics. I don’t know. Some people have just great genes.

“I told the president that if he had a healthier diet over the last 20 years, he might live to be 200 years old.”

“I don’t know. It’s just the way God made him,” Jackson said.

The physician’s press briefing came after Trump underwent his first physical examination as president on Friday at the Walter Reed National Military Medical Centre in Bethesda, Maryland.

Jackson said Trump received a perfect score on a cognitive test designed to screen for neurological impairment.

According to him, it is evident that the President did not suffer from mental issues that could prevent him from functioning in office and can serve out two terms of eight years.

“I’ve found no reason whatsoever to think the president has any issues whatsoever with his thought processes,” Jackson, a rear admiral in the Navy, said.

A book published earlier this month, “Fire and Fury” by Michael Wolff, asserted that even Trump’s own advisers and associates questioned his fitness for office.

Trump, the doctor said, asked for the cognitive test to answer his critics and attempt to quell questions about his mental abilities.

Jackson said with mostly normal results on a battery of tests and examinations “excellent”, Trump, 71, has remarkably good cardiac health, probably because he does not smoke or drink alcohol.

Jackson said the president sleeps only four to five hours a night but rarely sees the president overly stressed.

“He has a unique ability to just get up in the morning and just reset. He gets up and he just starts a new day,” he said.

According to him, however, Trump weighs 239 pounds, he is too sedentary and his cholesterol is too high, in spite of taking medicine to lower it.

“The president and I talked; he would like to lose 10 to 15 pounds. We talked about diet and exercise a lot,” Jackson said.

The physician, who was appointed to the White House post by President Barack Obama and retained by Trump, said that Trump’s diet had changed since he took office.

During the presidential campaign, Trump’s long-time personal physician, Harold Bornstein, had declared that Trump would be “the healthiest individual ever elected to the presidency”.