Slimming down usually means eating less along with exercising more. Most shortcuts just don't work. A five-year study from Wake Forest Baptist Medical Center found one that does.

Just add more soluble fiber to your diet.

The study found that for every 10 grams of soluble fiber eaten daily, visceral fat decreased by 3.7% over the next five years. You can add 10 grams of soluble fiber to your diet by eating two small apples, one cup of green peas and one-half cup of pinto beans.

Only the soluble type of fiber seems to lower belly fat. It also appears to lower cholesterol and blood sugar. Foods high in soluble fiber include oats, peas, beans, apples, citrus fruits, carrots and barley.

Visceral fat is also known as intra-abdominal fat or just plain belly fat. It's much more dangerous to overall health than subcutaneous fat, the fat which lies just under the skin. This means that someone's waist size may be a better indicator of their health than their weight is. Large waistlines mean large amounts of visceral fat.

There are two types of dietary fiber: water soluble and water insoluble. Only the soluble type seems to lower belly fat. It also appears to lower cholesterol and blood sugar. Foods high in soluble fiber include oats, peas, beans, apples, citrus fruits, carrots and barley.

Insoluble fiber aids digestion and has other benefits. This is the type of fiber found in wheat bran, nuts and many vegetables. But there's no evidence that insoluble fiber trims belly fat.

The study was of 1,114 adults, 339 of whom were African-Americans and 775 who were Hispanic-American. Ages ranged from 18 to 81. Diet was determined from a food-frequency questionnaire. Visceral and subcutaneous fat were measured from abdominal CT scans taken at the start of the study and five years later.

It's recommended that people who want to increase the amount of fiber in their diet do it gradually over a period of a few weeks. Drinking plenty of water also helps.

While soluble fiber decreased the accumulation of visceral fat, it did not decrease the amount of subcutaneous fat.

Another finding of the study was that participants who were moderately active (30 minutes of vigorous exercise two to four times a week) lowered their rate of fat accumulation by 7.4% in the next five years. This is double the decrease seen from eating 10 grams of soluble fiber. But the fiber results show that it is possible to lower belly fat just by making a simple dietary change.

Adding too much fiber to your diet too quickly can cause stomach problems such as gas and cramping. It's recommended that people who want to increase the amount of fiber in their diet do it gradually over a period of a few weeks. Drinking plenty of water also helps.

An article on the Wake Forest study was published online by the journal Obesity on June 16, 2011 and will also appear in a future print edition of the journal.