Charlie Sheen revealed on NBC's "Today" on Tuesday that he is HIV-positive as he sat alongside his doctor Robert Huizenga. Huizenga is a famous doctor who's appeared on many news and reaility shows. 

On the NBC morning show, Huizenga helped clarify what's going on with Sheen, while also confirming that the actor does not have AIDS. The clip can be seen below:

Huizenga, also referred to as "Dr. H," has appeared on NBC's "The Biggest Loser" over the past 14 seasons and has helped people battle obesity through nonsurgical methods. He has shown these methods by instituting a heavy exercise regiman on the show and has 15 published medical abstracts, according to "The Biggest Loser" website.

Dr. Huizenga Dr. Robert Huizenga, pictured here with an unidentified woman at Hope Ball Oct. 11, 2014, in Beverly Hills, California, has appeared on reality shows and news programs as a medical expert. Photo: Getty

The doctor started his career in 1983, serving as the team physician for the NFL's Los Angeles Raiders for eight years and as president and president-elect for the NFL Physicians Society for four years. Following his NFL experience, Huizenga wrote the book "You're OK, It's Just a Bruise: A Doctor's Sideline Secrets About Pro-Football's Most Outrageous Team," which sparked debate about the dangers of anabolic steroids. The book also inspired Oliver Stone's football film, "Any Given Sunday."

Viewers may know Huizenga from other shows. He has appeared on NBC, CBS and ABC Evening News, on "Nightline" and on "Larry King Live." He has also been involved as an expert in some legal cases, notably as an expert in both the criminal and civil O.J. Simpson trials, NBC said.

Huizenga grew up in Rochester, New York, before attending the University of Michigan for college and the University of Harvard for medical school. Currently, he is also Associate Professor of Clinical Medicine at UCLA.

The doctor is married to former Playboy bunny and model Wanda Huizenga, though TMZ reported in June 2012 that she had filed for separation. They have three children: Ashley, Troy and Hayley.