Angelina Jolie is partnering with Halle Berry for a new action movie, and sources say the mother of six is relying on her incredibly fit co-star to help her improve her slender physique. The two are set to produce and star in the thriller "Maude vs. Maude," but insiders suggest that 47-year-old Angelina is not yet prepared for the role.

"Angelina is far too thin," our source reveals. "She realizes she needs to gain muscle, and now that her work requires it, she's running out of excuses to avoid focusing on her health."

According to insiders, Jolie is turning to fellow Oscar winner, 56-year-old Halle Berry, to guide her through the transformation process.

"Angelina is in awe of Halle's physique," says the insider. "She wants to achieve a similar look, and Halle is more than willing to help her get there."

When Angelina starred in the action film "Lara Croft: Tomb Raider" in 2001, she appeared much healthier. Sources estimate that she needs to gain at least 15 pounds of muscle to regain that level of fitness.

"She knows it won't be easy, especially after more than 20 years," shares a source. "She's not in her 20s anymore, but she's committed to doing whatever it takes."

Halle, a firm believer in a "strict ketogenic diet," is confident that she can help Angelina both gain weight and tone up. According to insiders, Jolie has already adopted a rigorous diet and exercise regimen.

"Halle is very passionate about nutrition. She follows a paleo diet and is always encouraging others to try it," says the source. "She was delighted when Angelina sought her advice."

Under Halle's guidance, Angelina has started drinking bone broth, consuming more healthy fats, and lifting weights.

"Angelina may be frail and out of shape at the moment, but with Halle's assistance, she's determined to transform her body and excel in her role," concludes the insider.