Redmond O'Neal became a free man last October (12) after successfully completing a year-long court-ordered rehab stint following a number of spells in and out of jail and treatment centres to deal with substance abuse issues.
He stepped out for a topless stroll with his actor father on a beach in Malibu, California earlier this month (Jul13) and was almost unrecognisable with his shaved head and pudgy frame.
A source tells the National Enquirer his once-skinny frame has ballooned to an estimated 225 pounds (102 kilograms), and says, "He seems to have swapped one addiction for another."
Redmond, 28, had been battling addiction to narcotics for years and was behind bars when his mother died in June, 2009.
He regained his freedom last year (12) after a judge suspended his jail sentence for a 2011 arrest for heroin and firearms possession following the completion of a court-ordered inpatient treatment programme.