A man at his wit 's end after inexplicably piling on 150lbs in just a year has finally had his medical mystery solved after being diagnosed with Cushing 's disease - a rare form of brain tumor . Donelle Trotman , a father-of-two in his thirties from New York 's Staten Island , underwent a series of tests by doctors who could n't figure out his mysterious symptoms - major weight gain concentrated only to his upper body , as well as skin problems and crippling fatigue - but it was a medical intern who solved the riddle when he noticed unusual tell-tale stretch marks on his arms . Luckily for Mr Trotman , who told Today he had never been 'skinny ' , but never been 'overweight ' before got sick , surgery to remove the mass was successful , and doctors expect him to make a full recovery within a year . Scroll down for video . Transformation : Donelle Trotman , pictured ( left ) before he suddenly gained 150lbs and ( right ) as he is now , was diagnosed with Cushing 's disease , a rare form of brain tumor which is fatal unless treated in time . Mr Trotman first starting gaining weight three years ago . He was 180lbs when he was 18 , but after his illness took hold , he rocketed up to 366lbs . Cushing 's disease is caused by a tumor on the pituitary gland , located at the base of the brain . It triggers excess levels of the steroid cortisol to be released in the body . Symptoms include upper body obesity , a swollen face , acne , skin bruising and purple stretch marks . Untreated , Cushing 's disease can be fatal , but the prognosis is good if the growth is surgically removed in time . The disease affects fewer than 50,000 people in the U.S. each year . ' I doubled , like , I got a whole person on me , ' he said . 'It was just specific places ; my stomach , under my arms , my back of my neck , my face , the bottom of my back . 'My legs stayed the same for a long time . ' Despite running and lifting weights , he continued to expand , and was soon so tired all the time that even chewing left him out of breath . Unbeknownst to Mr Trotman , the tumor on his pituitary gland was causing his brain to produce vast amounts of a natural steroid called cortisol . Mr Trotman went to New York 's Lennox Hill hospital after he started experiencing double vision , but a slew of tests got doctors nowhere . It was a medical intern who one day noticed his unusual stretch marks and suggested he could be suffering from Cushing 's disease , which affects fewer than 50,000 people in the U.S. each year , and is fatal unless treated in time . Mystery : Mr Trotman , pictured with his girlfriend in 2013 after getting sick , experienced major weight gain concentrated only to his upper body , as well as skin problems and crippling fatigue . Getting worse : Despite running and lifting weights , Mr Trotman , pictured before ( left ) and after ( right ) , continued to expand , and was soon so tired all the time that even chewing left him out of breath . Clue : Mr Trotman underwent a series of tests by doctors , but it was a medical intern who solved the mystery when he noticed unusual tell-tale stretch marks on Mr Trotman 's arms . Since undergoing surgery to remove the growth , Mr Trotman has been gradually losing weight and returning to normal . 'It 's wonderful , ' he says . 'Every day it 's just like I feel a little stronger . ' There is an eight to ten per cent chase the disease will return , but if so , Mr Trotman will be able to catch it quickly .
Donelle Trotman , a father of two from New York 's Staten Island , saw his weight double to reach 336lbs in a year . Regular exercise failed to help him shift the pounds . After a series of tests which left doctors baffled , a medical intern noticed tell-tale stretch marks on his arms , a sign of Cushing 's disease . The rare form of brain tumor triggers the release of excess weight-building steroids . Mr Trotman had surgery to remove the mass and doctors say he will make a full recovery within a year .