Donald Trump has "incredible genes" and could have lived to 200-years-old if his diet had been better in recent years, the White House presidential physician said. Dr Ronny Jackson, who performed Mr Trump's first medical exam as president, declared him "fit for duty" physically and mentally. As well as a thorough physical Dr Jackson performed a "difficult" cognitive test and Mr Trump scored 30 out of 30. The doctor said: "He's very sharp, he's very articulate around me, I've no indication to be concerned about his thought process." Dr Jackson said he had not planned to do a cognitive test but Mr Trump asked him to, and he did "exceedingly well" on it. The doctor said: "If he had some kind of mental cognitive issue he would not have got 30 out of 30 on the test. He has no mental or cognitive issues." Donald Trump Credit: AP He said it was the first time a president had undergone such a test, and Mr Trump asked for it specifically so he could lay to rest recent speculation about his mental capability. In a recent book, Fire and Fury by Michael Wolff, White House aides were said to have questioned his state of mind, and Mr Trump responded by calling himself a "very stable genius". Last month, the president slurred his words while announcing a decision to recognise Jerusalem as the Israeli capital. Dr Jackson took responsibility for Mr Trump slurring his words during the speech, saying he had prescribed him Sudafed, a cold remedy, and that had dried up his mouth. Mr Trump's weight was 239 pounds. He had a Body Mass Index at the very top of the "overweight" range and just shy of "obese". Here is the release of President Donald Trump's medical exam by Dr. Ronny Jackson, on paper: https://t.co/kLR436GYM8pic.twitter.com/24zbLYQD0C— Lisa Feierman (@lisathefeierman) January 16, 2018 His resting heart rate was 68 beats per minute, and his blood pressure was 122/74. His total cholesterol was 223, which is higher than recommended, and had risen over the last year. Mr Trump takes a medication for his cholesterol, the doctor said. He also takes Propecia to combat male pattern hair loss. Dr Jackson said Mr Trump "could do with losing 10 or 15 pounds". He added: "We talked a lot about diet and exercise. He was more keen on the diet than exercise but we will do both." The physical part of the four-hour medical exam settled a long mystery over how tall Mr Trump is. He has claimed to be 6ft 3ins, while an old driving licence showed him as 6ft 2ins, leading to accusations he had exaggerated his height. Dr Jackson confirmed Mr Trump is 6ft 3ins. Asked how a 71-year-old man known to like hamburgers could be in "excellent" physical health, he said: "It's called genetics. Some people have great genes. "I told the president if he'd had better diet over the last 20 years he could have lived to 200 years old. The answer is he has incredibly good genes, it's just the way God made him. "He had great findings across the board but his cardiac health stood out. Hands down he is in the excellent range. "He continues to enjoy the significant long-term cardiac and overall health benefits that come from a lifetime of abstinence from tobacco and alcohol."