President Trump's critics looking to seize on his medical records to undermine his presidency or take away his powers are likely to be dissatisfied by the information that will be made public in January.

Trump is expected to have his first routine physical as president at Walter Reed National Military Medical Center in Bethesda, Md., on Jan. 12, which will partly serve to address some of the speculation that has been swirling about his health.

Trump's tweets and speeches have brought about various denunciations, as have his age, diet, and exercise choices. Before Trump's election, former President Barack Obama called him "unfit to serve." Rep. Zoe Lofgren, D-Calif., introduced a resolution in August calling for a mental and physical exam of the president to remove him from office. MSNBC host Joe Scarborough recently said Trump has dementia. And social media erupted with questions over whether he had a stroke when he appeared to be slurring his words.

The medical records may provide some clarity, but no law demands their disclosure or that they are complete. The release of health records is not the same as releasing tax returns — which Trump hasn't done — in which raw data are provided to the public to analyze. The president must consent to which details are released and with whom.

"Very few people have that kind of an exam where they would release everything into the public domain," said Arthur Caplan, founding head of the Division of Medical Ethics at NYU School of Medicine. "The Walter Reed physical is more for the president, president's family, and close advisers to see what they learn. Whether they share it with us is completely up to them."

Before leaving office, Rep. Jason Chaffetz, R-Utah, chairman of the House Oversight Committee, said he was considering filing a bill that would require presidents to undergo an independent physical and mental exam. Chaffetz said he wasn’t “talking about some of the rhetoric that’s flying around” about Trump, but added, “If you’re going to have your hands on the nuclear codes, you should probably know what kind of mental state you’re in.”

When asked about the details of the physical, the White House would share only the date and acknowledged that Dr. Ronny Jackson, the White House physician, would read the results. Walter Reed officials also declined to provide specifics. "To respect the privacy‎ of all of our patients both past and present we do not provide details of care or treatment plans," said Sandy Dean, a spokeswoman for Walter Reed.

If doctors were to leak information that wasn't in the read-out, they would be fired and lose their license for violating patient confidentiality laws.

"If the president has something wrong, we won't know," Caplan predicted, adding: "We have a long tradition of doctor-patient privacy. Nothing in law overrides that, even if you're the president."

A glowing report may invigorate critics.

"If it comes out rosy and positive, but does not contain a lot of information, people will still have the same doubts about him," said Barbara Perry, director of Presidential Studies at the University of Virginia's Miller Center.

She also pointed out that the exams of Trump's predecessors George W. Bush and Obama declared them "fit for duty."

"If that phase doesn't appear, then people will say, 'Is he not fit for office? Why didn't the doctor say that?' That may work against him that you have this precedent," Perry said.

What's in the physical?

A Washington Examiner review of past medical records shows significant variation in the physicals. The exams last about four hours, with the White House doctor sometimes taking part alongside other specialists. Other than weight and cholesterol levels, some records have indicated whether presidents had moles removed or received vaccinations.

Other information can potentially be more embarrassing, including whether the president has gained weight or has hemorrhoids, or whether he has ever had a sexually transmitted infection. An extensive mental health assessment isn't typically part of the exam.

"To be fair, the president isn’t ducking this," Caplan said of a mental health exam. "It’s just when Americans get physicals they tend to be literally physical — a lot more blood chemistry and a lot less psychiatric analysis."

But that doesn't mean no mental health exam would be included. Dr. Diane Meier, director of the Center to Advance Palliative Care and professor at Mount Sinai Hospital in New York, said assessments of memory, function, depression, and anxiety should typically be conducted for people over age 65. The screenings would be in the form of a questionnaire from a primary care doctor.

One of the earliest signs of memory problems, she said, is when "things you used to do before are now more annoying and difficult to complete," whether grocery shopping to prepare a specific meal or difficulties balancing a checkbook.

What we know about Trump's health

A patchwork of news reports and Trump's own medical records reveal some information about his health but still paint an incomplete picture. Without the details, the public has reacted with assumptions, speculation, and at times even ridicule. Some came after Trump's longtime physician, Dr. Harold Bornstein, wrote during the campaign that Trump "will be the healthiest individual ever elected to the presidency."

Dr. Lawrence Altman of the New York Times learned before the election that Trump takes antibiotics to control rosacea, a statin for elevated blood cholesterol and lipids, a daily baby aspirin to reduce the risk of a heart attack, and finasteride, a drug that promotes hair growth on the scalp. Trump's appendix was removed when he was 10, and when he graduated from college he was not drafted in the Vietnam War because at the time he had bone spurs in his heels, which are calcium protrusions that can be painful. Trump, 71, has never smoked tobacco or drunk alcohol, and his allies have marveled at his stamina.

Reports say he golfs for exercise, drinks a dozen Diet Cokes a day, likes fast food, and a well-done steak.

In September 2016, Trump weighed 236 pounds. At 6-foot-3, he is four pounds short of obese. In this way Trump is more like the average person in the U.S., where more than 70 percent of adults are categorized as overweight.

S. Jay Olshansky from the University of Illinois at Chicago, a leading researcher on aging, warned against drawing conclusions about people's expected lifespan just because of the way they eat, pointing to billionaire Warren Buffett, 87, who has a fast-food diet.

"The science tells us there are some people who are not susceptible to diet and other harmful behavioral risk factors, and he might be one of them," Olshansky said.

He also cautioned against determining people are unable to do their jobs based on age, saying that while the risks of having ailments rises as people get older it "doesn't mean they can't do their jobs or live their lives normally."

"It's not their age that should matter it’s their policies," said Olshansky, who believes in erring on the side of privacy when it comes to releasing medical information.

Perry, however, is of the view that full mental and physical health records and history should be disclosed by presidents.

"The role involves leading the free world and having to make split-second decisions about life and death," she said.

The political pressures of health

Since Ronald Reagan, releasing medical information has become more common for presidents. George H.W. Bush had at least four routine medical exams while in office, while Bill Clinton underwent six exams over two terms, George W. Bush had at least five, and Obama had at least four.

The 25th Amendment often emerges in discussions about a president's health. It allows the vice president, Cabinet, and Congress to take away the president's powers if they decide he is “unable to discharge the powers and duties of his office," by putting it in writing to the speaker of the House and the Senate president pro tem. The result can lead to a disagreement that Congress must resolve.

If the administration chooses to omit information about Trump's health, it wouldn't be the first time.

Grover Cleveland secretly had cancer surgery on a boat, and William McKinley almost died from pneumonia. Woodrow Wilson's wife carried out White House affairs for a time because he was paralyzed following a stroke, and Franklin D. Roosevelt had severe heart disease during his final campaign. The press was told Dwight D. Eisenhower was hospitalized because of an upset stomach, when in fact he had a heart attack. John F. Kennedy's Addison's disease, an endocrine disorder that can be life threatening, only became more public after he was elected.

It is not clear whether mental health issues can affect presidential decision-making and how to parse out each situation. Abraham Lincoln, for instance, had depression while in office.

But Olshansky's studies refute assumptions that being president ages a person because of its demanding schedule and high stress levels. Their personalty type allows them to thrive under stress, his research shows.

"Trump has come up against an incredible amount of stress in his presidency, he doesn't seem to be influenced by it in any way," Olshansky said. "That’s the unique nature of the folks running for president — they are able to handle that better than the rest of us."

He also has created an analysis to measure how long a person is likely to live, finding that the most important factors are education, income, smoking status, weight and height, marital status, and family history.

His prediction for Trump? That he will live until age 87.8, or more than eight years after a two-term presidency.