Dr. H From 'Biggest Loser' Drops $5.5 Million On Phat Malibu Mansion

Dr. H from "Biggest Loser" doesn't just help fat people with their problems -- he dropped $5.5 million on a sick mansion in Malibu ... to help folks of all sizes change their lives!!!

The good doc -- Robert Huizenga -- purchased the 9,750-square-foot casa at auction in July. But we're told the place isn't for him ... Dr. H will be using it as a wellness retreat where people (with fat wallets) can focus on making lifestyle changes through fitness, meditation and yoga.

FYI: He owns another mansion-based retreat -- located in the Hollywood Hills -- focused on weight loss. We're told the Malibu site is NOT strictly about shedding lbs.

As for the primo pad -- five separate buildings, 10.2 acres, 7 bedrooms, 7 baths, 360-degree views of the Cali coastline, outdoor cabana, pond, and an infinity pool overlooking the ocean, according to our friends at Trulia.

FUN FACTS: Before "Loser" Dr. H was the team physician for the L.A. Raiders and once wrote a book that inspired Oliver Stone's flick "Any Given Sunday."