"I would find myself exercising more and more and not seeing the results on the scale," Greene said.

Mercy Medical Center Dr. Kathryn Boling said the average woman gains between 12 and 15 pounds between the ages of 40 and 55. Boling said a combination of three factors causes middle-age weight gain in women.

The first factor is metabolism.

"Our metabolism decreases about 5 percent for every decade we are alive," Boling said. "So what you could eat when you were 20, if you ate that same thing when you're 40, you're going to gain weight."

The second factor is hormones.

"That's the premenopausal area, and these hormone changes that we go through predispose the body to put on weight, especially to have that weight around the belly area for women," Boling said.

The third factor is exercise.

"As we age, we are exercising, but we can't exercise at the same levels we did when we were in our 20s," Boling said.

Boling said what you eat is more important than how much you exercise. She said that to lose weight, you probably need to cut the carbs, and that includes sugar. But why?

"One of the things that happens with carbohydrates and when you're eating a lot of sugar, your body produces a lot of insulin and your body becomes a little insulin-resistant and that causes your body to take those carbs and turn them into fat," Boling said.

Greene said she stopped eating sugar, flour and wheat and lost 45 pounds, with the goal to lose another 5 to 10 pounds..

"It was really the telltale that what was really going in my mouth was what was going to create the success," Greene said.