(CNN) -- Adam Lambert used to be much bigger than he is now -- and his recent flashy behavior is due to a self-esteem boost after a major weight loss, he told a radio show.
The former "American Idol" finalist explained some of his onstage antics at the American Music Awards as part of overcoming image issues from his youth.
"I suffered from a little bit of an ugly-duckling complex in my early 20s. When I was in high school I was 250 pounds and that creates some stuff ... some body image stuff, some confidence issues. And I got a lot of my confidence from the validation I got as a performer," Lambert told the Morning Jolt's Larry Flick on Sirius satellite radio.
The singer does believe he could have made a better first impression to follow up his successful run on "American Idol" than he did with the much-maligned risqué dance sequence he did on the AMAs.
"I think in hindsight I look back on it and I go, OK, maybe that wasn't the best first impression to make again, the first second impression. I mean, I had fun up there," Lambert told Ellen DeGeneres on her talk show Tuesday.
The singer said he was concerned that fans who watched his performance -- in which he kissed a male band member and simulated oral sex with a dancer onstage -- felt "disrespected," he told DeGeneres.
"I respect people and feel like people walked away from that feeling disrespected. I would never intend to disrespect anybody. So that was not my intention," Lambert said.
The former "American Idol" finalist also said that his performance was shocking to some people because he broke away from the typical media-friendly portrayal of gay men.
"People aren't used to seeing gay man portrayed that way on TV. The gay male image in the media tends to be ... safe," Lambert said. "I was putting on a character, putting on a persona, being this kind of rock star, kind of dangerous kind of guy. ... I don't know, something came over me and got caught up in the moment and maybe went a little too far."
ABC, the network that broadcast the AMAs, received more than 1,500 complaints over Lambert's behavior on the program. The network subsequently canceled a scheduled live performance by Lambert on "Good Morning America" later in the week. CBS's "The Early Show" invited Lambert to speak and perform on that program following ABC's cancellation.
On "The Early Show," Lambert was joined by his mother, Leila, who said she was a little taken aback by her son's performance on the AMAs. She said she ultimately just went with the flow and was proud of him for being so inspiring to his fans.
His father took a harsher stance, Lambert told DeGeneres.
"My dad was like, 'Maybe you should apologize, Adam,' " Lambert said.
He said he told his father, "I don't feel like I did anything wrong -- it just wasn't maybe the right judgment call. It's a taste thing more than an obscenity thing. I think it's just a taste level."
But Lambert said he didn't fault "Good Morning America" for canceling his performance.
"I don't blame them. I got carried away. It was stuff that I did not do in rehearsal, so they were probably a little bit taken aback," he said. "They gave me a great opportunity to close the AMAs and I would never want to smack that gift horse in the mouth. I think they were taking a leap of faith having me do that, and it unfortunately it didn't work out as we all thought it would."