Most of us gain an average 20 pounds between the age of 25 and 55. But some people are able to take the weight off and keep it off. So how do they do it?

Diane Lobel lost 40 pounds and has kept it off for three years. She carries these before-and-after photos in her gym bag to keep her on track.

"The doctor is even happy. He thought I was a completely different patient. He had to check his records to make sure it was me," she remembers.

To unlock the secrets of successful dieters like Diane, Consumer Reports surveyed 21,000 people including those who've never had a weight problem.

"People who've always been thin typically aren't sitting around eating potato chips. Only three percent of the thin people we surveyed said they ate whatever they pleased and never exercised," explains Jamie Kopf Hirsh of Consumer Reports.

As for the successful dieters like Diane, most lost the weight without the help of a diet program, diet pills, or a medical treatment. Their strategies were similar to those of the naturally trim.

"Portion control is a given. I have to make sure I don't go overboard on anything that I eat," she says.

Other winning strategies: eating lots of fruits and vegetables, opting for whole-wheat breads and other whole grains rather than white flour, and limiting fat.

That, plus exercise --any exercise. And having realistic goals, keeping expectations in check means you don't get discouraged.

Sometimes people argue it costs more to eat right, when in fact, it should cost less. The more processing that goes into food the more expensive it can be to save on calories, salt and money.

Eat local fruits and vegetables "in season". Changing what you eat with the seasons for the rest of the year buy frozen or watch flyers for specials on imports. Eat beans, they are a cheap versatile source of protein and fiber too and consider buying a slow cooker that make easy one pot meals using more economical cuts of meat.

The survey also found those who weigh less eat out less save money and pounds!

And if you don't want to cook every night cook for the whole week on one day or evening then you can portion the meals out so all you need is a quick warm up in the microwave for those days when you are "too busy" and tempted to just buy fast food.