Transcript for Man Loses 300 Pounds After Major Lifestyle Change
Reporter: Brian beck has been on the heavier side of the scale for most of his life. The doctor put me on skim milk at six months old because i was gaining weight too rapidly. Reporter: By the time he graduated college he was tipping the scales at over 400 pounds. He found a job in radio where he could hide behind his voice. I was able to have a career entertaining without having to be seen. Reporter: But by 2003 brian's weight wasn't just affecting his personal life, it was affecting his career, as well. I had an interview to go to orlando and went over to get my ticket. And they said, you need two. You take u a row basically. Reporter: That's when he decided to have gastric bypass surgery. He lost nearly 200 pounds but didn't change his eating habits and gained all the weight back. After getting married in 2007, a second wake-up call. I'm on the phone with my wife and I just said, I can't live like this anymore. I can eat better. I can change my health. Reporter: Brian starting changing his life slowly walking his dogs around the block and cutting out processed foods from his diet. Over 2 1/2 years more than 300 pounds melted away. Are you happy? I couldn't be happier. I never knew life could be this good honestly. Reporter: What was a meal like for brian at 480 some odd pounds. two pizzas and a big order of cheesesticks along with that. Now I eat a lot of fresh fruits and vegetables. I do eat meats. I eat a lot of chicken, I'll eat steak. Reporter: Now 40 years old brian has decided to share his experience with others. He's a personal trainer and his clients include people who knew him at his heaviest weight. So what do you think about the new brian? I think he's awesome. Thank y, buddy. Inspiration totally. Reporter: I couldt help but pick up some tips myself. Oh. He even kept a memento if his heavier days to remind him hoi far he came. I found an old pair. Wasn't at my biggest but close. I'm in one leg now of my old jeans. Reporter: For "good morning america," rachel smith, abc news, plano, texas. Joining us now is the host of abc's extreme makeover weight loss edition and author of "choose to lose "gma" special weight loss contributor chr powell and, chris, a number is one thing but a visual always helps so can you show us -- absolutely. These jeans are heavy. There's a lot of denim. It could be a blanket. These are size 58 here and this is what he was in when he was 475 pounds, 175 pounds -- he's smaller than I am. He's ripped. Yes. And explain to people, though, it's not -- it's not easy. He still fought with it. He had bypass surgery. He lost 200 pounds and then gained it all back. Yeah. Does that happen a lot and what advice do you have for people who have that severe yo-yo? It does happen and I see it all too often. What happened was he was so busy focusing on altering his body he didn't change his mind. That's where transformation happens up here first then he got it. He went through that mistake. He learned from it and then he said, o. Wait, I'll do this the right way. I'll go walk my dog and start one step at a time. I see it a lot with gastric bypass, lap bands, I'm not for it or against it but a tool people use to believe in themselves again. What happens when they start to spiral? Do they give up right away? Hard to imagine you could climb that high. All too often they do. As soon as they fall off once, hands go up in the fail, I knew I couldn't do this. We can fall without failing. Best thing to do if you do spiral out of control, confess. That's what the support system is for. In every transformation we need to surround ourselves with people who love us. Set up realistic expectation. How hard is it to maintain it? That's a whole new journey. The best thing and what I love about his story, he's training now. He's found another purpose and it feels so much better than food ef ever did. He always has to look forward to something more than food. Nothing tastes as skinny looks. It's true. You guys both knew that. All right, lara. It's about changing your relationship with food. Almost like you have to have a good breakup with food as opposed to a bad breakup. He started to look forward to other things. As soon as he's on the journey stepping on the scale and seeing the loss, it was great. People supporting him but now that he's where he's at he doesn't see the change on the scale anymore but he gets that feel-good from heading other people. Nothing feels as good as service towards others. Skinny looks good. Congratulations to brian. What an inspiration and thank you for bringing us yet another great story.
This transcript has been automatically generated and may not be 100% accurate.