Jess Brolin, the brother of No Country for Old Men star Josh and stepson of Brolin's wife Barbra Streisand, had been living off his inheritance following the tragic death of his mother Jane Cameron Agee, who was killed in a car accident in 1995.
But the National Enquirer reports the overweight 39 year old's money ran out earlier this year, leaving him completely broke and forcing him to move out of his rented $850 (£531)-a-month apartment in Ventura, California in May.
A source tells the tabloid, "Jess was left a six-figure trust after the death of his mother and has been living off that ever since. But that ran out in May, and since then Jess has been living in shelters, staying with friends or sleeping in his banged-up pick-up truck on the streets of Oxnard or Ventura, California."
And the insider claims Jess, who tips the scales at over 300 pounds (136 kilograms), is doing little to change his lifestyle: "Jess doesn't seem to do much more than eat and sleep."
But James Brolin and his wife Streisand are refusing to give up on the actor's struggling son.
In a statement, the couple says, "We have offered help and support and will continue to do so. We love him very much and want only the best for him."