(CNN) -- When Drew Manning stepped out from behind the cardboard cutout of his former fat self on Monday, the audience of "Good Morning America" was appropriately shocked.

The fitness trainer's journey had come to an end after successfully losing more than 70 pounds -- six months after he purposely gained the same amount. "Like it never happened," host George Stephanopoulos said.

"Kind of," Manning said. Both Manning and his wife, Lynn, can attest that a lot actually has changed in the past year. While Manning's body may have returned to its six-pack heydays, his mind, in many ways, has not.

Always a fitness junkie, staying in shape comes naturally for Manning. He's that guy at the gym the rest of us love to hate, the one who likes to use his biceps for pumping iron instead of changing channels, and who prefers sucking down a spinach shake to indulging in a brownie sundae.

Because of that, Manning was a "judgmental" trainer, his wife says. "He would look at someone who was overweight and say, 'They must really be lazy.'

"I was convinced people used genetics or similar excuses as a crutch," Manning writes in his new book, "Fit2Fat2Fit." "You either wanted to be healthy or you didn't."

Defining the new male body ideal

That point of view wasn't helping Manning help his clients. When he failed yet again to push someone over to the light side, he knew something was wrong. In order to better understand the struggles his clients were facing, he had to face them himself.

He gave up the gym and started consuming junk food, fast food and soda. In just six months, he went from 193 pounds with a 34-inch waist to 265 pounds with a 48-inch waist.

Lynn saw the difference in her husband in less time than that. He became lethargic, stopped helping around the house and was less than eager to play with their 2-year-old daughter.

"He was so insecure -- saying 'I'm so fat. I look so horrible,' constantly complaining about how he looks," she said.

Manning says he didn't realize the effects of his weight gain would be more than physical. It altered his relationships and his self-confidence. Returning to the gym after the Fit2Fat portion of his journey made him nervous. The fact that he had to do push-ups on his knees was almost humiliating.

"The biggest thing [I learned] is that it's not just about the physical. It's not just about the meal plan and the workouts and those things. The key is the mental and the emotional issues. I realized those issues are real."

Of course, Manning had his critics. Experts said that his stunt was dangerous. His blood pressure and cholesterol shot up with such dramatic weight gain. But Manning has no regrets. The followers on his website have encouraged him with their own tales of weight loss.

"We see the success stories of people losing all this weight, but it's more common now," he says. "To see someone do it in reverse on purpose -- it's mind blowing. A balance of craziness and inspiration."

Manning suffered through soda deprivation headaches and food cravings on his way back to fit. The journey was easier for him than for most, he'll admit, but he's eager now to provide tips for others to follow in his footsteps.

Lynn is just glad to have her husband back, maybe a bit better than he was before. Before Fit2Fat2Fit, the self-described foodie wife would make treats, and Manning wouldn't even look at them.

"Now he craves them," she says with a laugh. "It might be cruel, but I like that. I like that he's humanized."

I read about this earlier.

It's interesting that he found out that gaining all that weight affected more than just his waistline...it affected his mood and even his relationship.

PurpleJedi said:

I read about this earlier.

It's interesting that he found out that gaining all that weight affected more than just his waistline...it affected his mood and even his relationship.

Yep! Most people who have never had a weight problem don't realize all of the emotional effects being obese has.

He's lucky he didn't have a heart attack.

Genesia said:

He's lucky he didn't have a heart attack.

Shame he couldn't do anything about that smile

Genesia said:

He's lucky he didn't have a heart attack.

I assume that he's young and healthy enough to be able to handle it.

Actually...I think that pro bodybuilders do this sort of thing on a yearly basis...they swell up to gain size then cut weight to get shredded.

does he think that "fat" and "hairy" come together???

NDRU said:

Shame he couldn't do anything about that smile

is he smiling? I thought he was taking a shit

by the way, steroids, anyone?

[Edited 6/6/12 6:08am]

JoeTyler said:

NDRU said:

Shame he couldn't do anything about that smile

is he smiling? I thought he was taking a shit

by the way, steroids, anyone?

[Edited 6/6/12 6:08am]

Actually, he'd probably be full of veins and acne if he was a roid head.

I see plenty of them at my gym.

PurpleJedi said:

JoeTyler said:

is he smiling? I thought he was taking a shit

by the way, steroids, anyone?

[Edited 6/6/12 6:08am]

Actually, he'd probably be full of veins and acne if he was a roid head.

I see plenty of them at my gym.

yeah, that's true, the guy seems like the perfect example of special diet + intense/professional training program

JoeTyler said:

PurpleJedi said:

Actually, he'd probably be full of veins and acne if he was a roid head.

I see plenty of them at my gym.

yeah, that's true, the guy seems like the perfect example of special diet + intense/professional training program

...and let's not forget "being able to workout all the time 'cuz it's your JOB."

PurpleJedi said:

JoeTyler said:

yeah, that's true, the guy seems like the perfect example of special diet + intense/professional training program

...and let's not forget "being able to workout all the time 'cuz it's your JOB."

that's why trainers and ex-convicts are the only ones who are truly bulky

JoeTyler said:

PurpleJedi said:

...and let's not forget "being able to workout all the time 'cuz it's your JOB."

that's why trainers and ex-convicts are the only ones who are truly bulky

Maybe if I ever get REALLY serious about getting in top shape, I'll start by mugging some old ladies.

Most interesting part to me is the fact before the weight gain, he didn't eat junk food. After he started eating those foods, he developed cravings for it, even after losing the weight.

JoeTyler said:

NDRU said:

Shame he couldn't do anything about that smile

is he smiling? I thought he was taking a shit