Schallern told CBS News when she was in just the first grade when her mother put her on a diet.
"There was just this weird relationship with food in my house, it was sneaking food," she said.
Food, to her, was comfort, and by the time she was in junior high, she was 200 pounds.
"I did the iceberg lettuce and water diet, which I invented myself," Schallern said, "And it just doesn't work."
Schallern said she reached a point in college where she thought there was no hope; she was just a big girl -- someone who would never be in shape.
She explained, "I was like, 'I'm just not going to be able to lose weight. I can't lose weight, I'm not going to exercise, I'm just going to eat what I want.'"
Food was her friend, Schallern said.
"When I was alone I was upset and I wanted comfort I went to food, when I was happy and I wanted to celebrate I went to food," she said. "Food never judged me, it was predictable. It always tasted the same."
But, when she reached 300 pounds at the age of 30, Schallern knew this was her breaking point.
"I really felt like I was trapped in a cage," she said. "Sometimes I would look in the mirror and (say), 'That's not someone I even recognize.' Like I was living in someone else's body."
Schallern planned to get gastric bypass surgery to lose the weight, but one of the requirements is that you prove you had tried to lose weight other ways, so she went to Weight Watchers to fulfill the requirement. However, she ended up doing the program, and losing almost 145 pounds.
She now weighs about 155 pounds.
Appearing on The Early Show Wednesday, she said she thinks she is still the same person. "I think I was just let free. I'm able to do so many things that I wanted to do before. Physically I don't have this guard up anymore. And it's the same person, just I can show the world who I am now."
Asked if the experience of the weight loss is what she had imagined, she told co-anchor Maggie Rodriguez, "Life had to get better before I lost the weight. I had to love myself and respect myself in order to take care of myself and my body."
"I think you have to get that relationship with yourself right before you get any relationship with food or exercise or diet or anything like that," Schallern said.
When she considered the gastric bypass, she really thought she couldn't lose the weight on her own. "And I knew in order to get a doctor to approve it I would have to go through some weight loss regimen and showing it wasn't happening."
Remembering her first weeks on Weight Watchers, Schallern said, "I could hardly eat all of the food at the beginning and it just worked and it's something I remember thinking like eight weeks into it, I can do this for the rest of my life."
She has been keeping up her healthy eating regimen since then. Schallern shared a typical daily menu with "The Early Show":
SARAH'S DAILY MENU:
Egg white omelet with spinach
1 slice of white wheat toast
Low fat yogurt with blueberries
94 percent fat-free popcorn
Turkey sandwich on wheat or grilled chicken salad with vinegar
Rotisserie chicken, green beans with almonds (frozen) and baked potatoes
Low fat ice creams, No Pudge brownies
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