( 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 did n't . '' The link between fat and cancer . That point of view was n'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 did n'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 . A fat girl gets naked . `` 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 . Power walker loses 150 pounds . 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 would n'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 . '' CNN 's Ashley Strickland contributed to this story .
Fitness trainer Drew Manning wanted to better understand his clients ' struggles . Manning gained 70 pounds on purpose so that he could lose it . He was able to do this by eating a diet of mostly raw food, and exercising for an hour every day.