Doctors at the Burujil Hospital in Abu Dhabi told that Eman's death was due to heart and kidney disease.
In a video released by the hospital, a visibly emotional Shaimaa Selim, Eman's sister, said her condition had improved tremendously after she was admitted to the Abu Dhabi hospital.
Eman was at the hospital in Abu Dhabi being treated by 20 medical professionals, after a major weight-loss surgery in India.
She was under treatment for three months in the Saifee Hospital, Mumbai during which time she lost almost 250 kilograms.
By the time she left Mumbai after the operation, doctors said El Aty had lost more than half her original weight.More news: Reports disagree whether North Korea quake was man-made
She was later diagnosed with the parasitic disease called Elephantiasis - which made her constantly hungry.
Ms Ahmed's sister had alleged that her treatment in Mumbai had been far short of satisfactory and the family had been misled. Eman Ahmed's death comes as a shock to many, however, the young woman was suffering because of her weight-related ailments for a long time.
Eman Ahmed Abd El Aty, from Alexandria, Egypt, weighed 1,100lbs before her surgery.
She died just a week after celebrating her 37th birthday. Egypt Air specially adapted a cargo plane to transport her to India. Once the bariatric surgery was completed, it resulted in her losing an impressive 660 pounds (300kgs). Doctors managed to move her after a wall was brought down to bring her out.
The former world's fattest woman - who weighed 500Kgs - has died aged 37. "She was infected with a very aggressive kind of bacteria", said Dr Neehad Khawala, head of intensive care unit at Burjeel Hospital.