Melissa Dilling, 28, of Indianapolis is losing weight by playing a numbers game. Every day she tries to limit her calories to 1,500 and burn off 500 or more with exercise.

As a result, she lost 25 pounds in four months on the USA TODAY Weight-Loss Challenge.

Dilling, who is 5-foot-9â½, is down to 182 from a high of 207. "This loss is all from eating less and moving more," she says.

She is one of the readers who volunteered to try out the program at the end of September. This year's seventh annual challenge is designed to help people lose 10 pounds in 10 weeks.

The advice offered in the plan is based on the latest scientific evidence, which shows that dieters generally lose about 5% to 10% of their starting weight in the first three to six months on a program. For many people, that's a loss of 10 to 20 pounds. Stories about readers who have trimmed down will be featured every Monday through early March in the newspaper and at

Before starting the program, Dilling tried to eat sensibly but often ate too much, drank high-calorie sodas and didn't exercise regularly. Plus, she spends most of her day sitting, even though she's in charge of recreational programming for a city park. She wanted to lose weight because she and her husband, Joe, would like to start a family soon, and "I didn't want to be large already and then have to lose pregnancy weight."

One of the biggest changes she has made is stepping up her physical activity. During her lunch hour, she walks for 30 minutes. At night, she goes either to an intense kickboxing class or to the gym and works out on the elliptical or stationary bike. Her husband has started going to the gym with her.

Early on, she invested in a Bodybugg, a device that measures motion, heat flux, skin temperature and other factors to determine how many calories she is burning. She paid about $200 for it and says it was worth it because it has kept her honest and motivated.

After losing the first 20 pounds, Dilling let her guard down and didn't exercise as much, and one day she ate four or five cookies. She didn't feel good afterward, and she realized she had to burn off another 200 calories to undo the damage from the cookies. So she got back on track.

When she feels hungry, she drinks more water or has a piece of fruit: "Apples and bananas are my best friends right now."

Overall, she feels as if the weight has melted off. People are starting to notice and congratulate her. "It felt great to hear my mother say: 'Melissa, I can really tell you've lost weight. I'm proud of you.'

"I feel great on this plan. I can really tell the difference in my body. I will keep going until I feel like I look as good as I should."

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