A new book claims that President Trump has been lying about his height in order to avoid being categorized as obese.

"An overweight seventy-year-old man with various physical phobias (for instance, he lied about his height to keep from having a body mass index that would label him as obese), he personally found healthcare and medical treatments of all kids a distasteful subject," Michael Wolff wrote in Fire and Fury: Inside the Trump White House.

This isn't the first time Trump's height has come under scrutiny. A copy of his New York driver's license in Politico records his height as 6-foot-2, but in a letter dated Sept. 13, 2016, Trump's longtime physician, Dr. Harold Bornstein, wrote that Trump's height was 6-foot-3 and that he weighed 236 pounds.

The latter combination makes his body mass index 4 pounds short of "obese," and instead makes him "overweight." More than 70 percent of U.S. adults have a body mass index categorizing them as overweight and nearly 37 percent are categorized as obese, according to the Centers for Disease Control and Prevention.

If Trump's height is 6-foot-2, then his weight would place him in the "obese" category. Trump is scheduled to undergo a routine medical exam Jan. 12 that is likely to include his height and weight.

During his campaign, Trump addressed his weight after handing his doctor's letter to Dr. Mehmet Oz, host of the "Dr. Oz" show.

"I think I could lose a little weight," Trump told Oz. "I've always been a little bit this way. ... If I had one thing I'd like to lose weight, but it's tough because of the way I live." He added that he would like to lose 15 to 20 pounds.

A correction issued by the New York Times in September 2016, ahead of Trump's election, stated that a story "misstated the candidate’s height, as reported in a recent letter from his physician. Mr. Trump is 6-foot-3, not 6-foot-2." The story was written by Dr. Lawrence Altman, who has for decades written about the health of presidents and presidential candidates.

The White House and reporters who cover Trump have said that Fire and Fury contains many inaccuracies.

Related: Trump's medical exam will disappoint critics. Here's why