Jackson said he'd be arranging to have a dietitian consult with the White House chef to cut calories and would be recommending a low-impact, aerobic exercise program for Trump, with the aim of shedding 10 to 15 pounds this year.
"He falls into a category that portends years of event-free living", Jackson said.
He gets plenty of exercise on the golf course and at the White House complex, the President said on Wednesday. The question arose after a week of speculation about the President's mental fitness for office, spurred by the publication of a damaging book that suggested Trump's own aides worry about his stability.
As a result, the president can boast a reasonable 122/74 blood pressure and solid circulatory and respiratory health, Jackson said. "And, I have never known him to repeat himself around me", Jackson said.
Trump is taking the prescription medicine Crestor to lower his cholesterol, Jackson noted.
Mr Trump underwent the medical exam at Walter Reed National Medical Centre last week and Dr Jackson issued a blanket declaration that Mr Trump was in "excellent health".
He passed a battery of heart exams including a stress test that Jackson said showed an above-average exercise capacity for a man of his age, despite some calcium buildup in his arteries.
"For health, the issue is not how much you weigh, but how much abdominal fat you have", a 2005 Harvard Medical School blog post said. The doctor said he is going to try to put the president on a diet but joked that the commander-in-chief might just live to be 200.
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"But any benefit", Newsweek said, "assumes Trump will take it regularly, which ... only about 50 percent of people do after six months".
But hundreds of people tweeting with the #GirtherMovement hashtag are accusing the USA president, 71, of lying about his weight.
Still, at the president's request, Jackson did an assessment to screen for any cognitive impairment such as Alzheimers - and Trump got a ideal score.
Some critics say that the rather short screening test doesn't provide a complete picture of a participants mental health.
The president's weight puts him just a hair below the Center for Disease Control's obesity threshold, with a body-mass index of 29.9. "Some people have great genes". So, that's his current exercise regimen: walk, this, that, run next door.
"There's no indication whatsoever that he has any cognitive issues", Jackson told reporters at a White House news briefing. The president has also noted that he sleeps only about 4 to 5 hours per night, and Jackson confirmed that.
Overall, Jackson said he was impressed by the president's health, saying tests revealed no evidence of cancer, lung problems, diabetes or joint problems.