Brad Pitt has given his longtime partner Angelina Jolie "an ultimatum that she has to start eating."

The Hollywood pair raise six children together; adopted kids Maddox, ten, Pax, eight, and seven-year-old Zahara as well as biological children Shiloh, five, and three-year-old twins Knox and Vivienne together.

Angelina is rumoured to be pregnant with another set of Brad's twins.

Brad is reportedly concerned for the health and wellbeing of his love and his unborn children, as the loving patriarch believes Angelina is too thin.

"It's really got Brad terrified," a source told OK! magazine. "Brad gave Angie an ultimatum that she has to start eating for the sake of the twins' health."

It is speculated that Angelina began battling issues with her weight nearly a decade ago.

"She's been extremely thin since [her and Brad's 2004 movie Mr and Mrs Smith]," the source revealed. "She's never properly put that weight back on."

Angelina's frame altered drastically following the birth of her twins Knox and Vivienne in 2008. The actress wasn't happy with how her body changed.

"When she went to Cannes eight months after the twins were born, she had the tiniest of curves in her hips and stomach," the source explained. "I think it was the most beautiful she's ever looked. But I don't think she felt that way."

Brad is prepared to take a stand for Angelina's wellness.

"Brad is determined to see her gain some weight," the source said. "And this time he's not going to back down. Brad needs to get her to start eating for at least one."