how is the most overweight person in the world and how much is his weight in kg and punts

The most overweight person in the world was Jon Brower Minnoch, an American man who weighed approximately 635 kilograms (1,400 pounds) at his heaviest.

why did he get overweight like this

Jon Brower Minnoch's extreme obesity was attributed to a combination of factors, including a genetic predisposition to obesity, a lack of physical activity, and a diet high in calorie-dense and unhealthy foods. Additionally, he suffered from a rare condition called massive generalized edema, which causes excessive fluid retention throughout the body. This condition contributed to his rapid weight gain and difficulty in losing weight.