An obese mother in the US is trying to put on weight in order to become the world's fattest woman.

Donna Simpson, from New Jersey, weighs 273kg but told the Daily Mail newspaper she had her heart set on reaching her goal weight of 1000lb (450kg) in two years.

The 42-year-old already holds the title of the world's fattest mother after giving birth to her daughter in 2007 when she weighed 241kg.

"I'd love to be 1000lb ... it might be hard though, running after my daughter keeps my weight down," Ms Simpson told the Daily Mail.

Ms Simpson, who needs a mobility scooter to go shopping, eats huge amounts of junk food each week and tries to move as little as possible so she doesn't burn off as many calories.

"I do love cakes and sweet things, doughnuts are my favourite," she said.

Ms Simpson said she also loved eating sushi and would often eat 70 big pieces in one go.

Her 49-year-old partner Philippe — who she met on a dating site for plus-size people — was encouraging her to reach her goal, she said.

"I think he'd like it if I was bigger ... he's a real belly man and completely supports me," she said.

To put on enough weight, Ms Simpson will need to eat 12,000 calories a day, which is six times the recommended daily intake for women.

In order to pay for the enormous amounts of food she is eating — her weekly grocery bill is $815 — Ms Simpson makes money by running a website where men pay to watch her consume fast food.

In order to pay for the enormous amounts of food she is eating — her weekly grocery bill is $815 — Ms Simpson makes money by running a website where men pay to watch her consume fast food.