If President Trump really is the picture of extraordinary vitality portrayed by the White House physician this week, he is defying long odds, according to experts and medical research.

Tuesday's depiction of Trump as much healthier than the average 71-year-old means he is managing to escape the consequences of a lack of sleep, the dangers of significantly elevated "bad cholesterol" and the well-established health effects of obesity, poor nutrition and lack of exercise.

That's certainly possible, but some experts were skeptical in light of his high-fat diet, his aversion to exercise and the photos they see of the president every day.

"The health report sounds like one for a Third World dictator. No contrary information is permitted," Marion Nestle, a professor of nutrition, food studies and public health at New York University, wrote in an email. "Therefore, it's impossible to discuss this without more genuine information."

In a relentlessly glowing description of the president's health at Tuesday's news conference, White House physician Ronny L. Jackson declared that Trump's "overall health is excellent" and predicted he "has a very strong and a very probable possibility of making it completely through his presidency with no serious medical issues."

"Some people have just great genes," Jackson said. "I told the president that if he had a healthier diet over the last 20 years, he might live to be 200 years old. . . . He has incredible genes, I assume." Trump has never smoked, which removes one of the gravest preventable threats to his health, and does not drink.

Jackson conducted Trump's three-hour physical exam, which included an EKG, a CT scan and an exercise capacity test, and consulted with a dozen other experts. Jackson, who has an office near Trump's, speaks with the president each day and has traveled overseas with him, both of which allow Jackson to gauge the president's physical and mental health.

"We'd get these 14-, 16-hour days, and the staff is just spent after a while," Jackson noted about long trips. "And I'll tell you, out of everybody there, the president had more stamina and more energy than just about anybody there."

But some critics found parts of Jackson's presentation a bit too positive. Some said it was convenient that Trump, at 6-foot-3 and 239 pounds, is a mere 16 ounces short of being technically obese. And that, they said, is at the height reported by Jackson; on his driver's license, Trump is listed at 6-foot-2.

But that distinction may obscure the real issue.

"We do know that the president is at an unhealthy weight, and it's splitting hairs whether he is overweight or obese," said Marian Neuhouser, past president of the American Society of Nutrition and a professor at the Fred Hutchinson Cancer Research Center in Seattle. "Whether his BMI is 29.9 or his BMI is over 30, he's at an unhealthy weight."

The health report did not reveal Trump's waist circumference, she noted. But visually, he has abdominal obesity that is associated with poorer than average health outcomes, including cardiovascular disease, diabetes and colorectal cancer, said Neuhouser, who was a member of the committee that drafted the 2015 government dietary guidelines.

Jackson said Trump is eating better now that he lives in the White House, where the staff prepares meals more healthful than the McDonald's fare he has long favored.

Trump told Reuters on Wednesday that he gets plenty of exercise on the golf course and at the White House complex. "I get exercise. I mean, I walk, I this, I that," Trump said during an Oval Office interview. "I run over to a building next door. I get more exercise than people think." He said he had impressed medical staff with his recent performance on a treadmill.

Trump has said he sleeps only four to five hours a night, another element of his lifestyle that Jackson remarked upon.

"That's probably one of the reasons why he's been successful, I don't know. Because, me personally, I need a lot more sleep than that," Jackson said. "But he's just one of those people, I think, that just does not require a lot of sleep."

Research has shown that there are rare individuals who function well on four to six hours of sleep, said Ying-Hui Fu, a professor of neurology and neuroscience at the University of California at San Francisco, who has studied the regulation of sleep for 20 years.

But for the vast majority of others, long-term sleep deprivation is a serious threat to well-being. It weakens the immune system and is associated with higher levels of metabolic problems, including diabetes, she said. Cognitive function and energy-level decline and the risk of depression and dementia increase, Fu said, because the brain and body aren't given enough time to flush waste products and replenish resources.

"Sleep is one of the most important things for our survival," Fu said. "I would say right after air and water . . . and before any food."

One result of Trump's coronary tests alarmed cardiologists. Even though he is on the statin Crestor daily, the president's low-density lipoprotein — his bad cholesterol — was measured at a troubling 143.

Research shows that patients have a wide range of responses to statin therapy, said Richard Chazal, immediate past president of the American College of Cardiology, but in some cases it can lower LDL levels as much as 40 percent. That means that Trump's cholesterol levels, if they were measured off medication, could be seriously elevated. Another possibility, some cardiologists said, is that Trump doesn't take the medication faithfully.

"It's reasonable to assume that untreated his LDL would be above the number we heard," Chazal said.

Chazal disputed a CNN report Wednesday that high levels of calcium in Trump's blood are an indication of heart disease. Statins often increase calcium scores to the point that the measurement becomes useless as an indicator of coronary problems, he said. Research supports the idea that use of those scores to indicate heart disease is controversial at best.

"The literature is clear that patients placed on statins have a calcium score that is higher" than it would be without that medication, Chazal said.

Jackson said he is planning to increase Trump's medication and put him on a diet and exercise regimen, though he maintained that Trump's coronary health is superb.

"He has incredible cardiac fitness at this point in his life," Jackson said.