The latest news in the world of nutrition is that not all fat is evil.

But that doesn't mean it's time to go rip open a bag of potato chips and start grilling a big steak. There are some parameters to this whole fat issue. Authorities on dietary guidelines agree that fat is needed for health, but there are guidelines for the sources and amounts.

For many years, the American Heart Association and other health organizations have encouraged the American people to keep their total fat intake to less than 30 percent and reduce cholesterol in their diet. Eggs, with their high cholesterol content of 213 mg per yolk, became almost taboo. Diet-conscious people turned to eating vegetables and drinking skim milk.

But there were some who questioned the wisdom of these dietary guidelines. University of Illinois Emeritus Professor Fred Kummerow was one who disagreed with the low-fat guidelines.

"There is a mindset today that fat and cholesterol are bad, which is false," he declared. He pointed to populations that had low dietary cholesterol intake, such as the people of India, and noted that these people also develop heart disease. He feels that the low-fat restrictions, "drive consumers to avoid nutrient-dense foods such as meat, milk and eggs."

But when people reduce the amount of meat, dairy products and eggs in their diets, Kummerow said that they also reduce the intake of protein, vitamins, magnesium and several important trace minerals.

Fat actually has several important functions, according to Kummerow. Fat contains linoleic acid, which helps the body produce a substance that keeps blood flowing through arteries. Kummerow also worked with cardiologists to establish that people on low-fat diets have higher homocysteine levels.

Kummerow is not alone in his questioning of low-fat diets, Dr. Udo Erasmus, a nutritionist who has spent more than a decade investigating his theories, has written a book titled "Fats That Heal, Fats That Kill." His research has determined the fats that can increase metabolic rate, help lose weight, improve digestion, promote cardiovascular healing and increase energy.

One of the statistics that intrigues Erasmus is that as Americans lowered their fat intake from 42 percent to 35 percent of their diets, the number of obese people rose from 20 percent to 33 percent.

"Fats don't make people fat," Erasmus firmly claimed. "What makes people fat are sugar, sweeteners and carbohydrates. When you don't get the fats you need, you develop cravings and end up eating carbohydrates. When you eat more carbohydrates than are needed, they are stored and you end up wearing around that fuel. When you get the fats you need, you are less hungry."

Erasmus distinguishes between good and bad fats and oils. An example of a harmful fat is the hydrogenated fat found in breads, cakes, cookies and margarine. These fats have been changed chemically and interfere with functions of the body. The good fats, when used in a properly balanced form, will increase the quality of life significantly, he said.

"These are essential fats. The body can't make them. They have to come from food. They are required by every cell, tissue, and organ in the body," Erasmus said. "They are required for brain functions, help with autoimmune conditions, increase energy levels, lift depression, help the kidneys dump water, and protect DNA from damage. If you don't get them, everything falls apart," he warned.

Erasmus gives specific recommendations about how to add essential fats and oils to a diet in his book. He prides himself with writing in very understandable language and avoids using difficult terminology.

"The book is written so some one who is 15 can understand it," Erasmus said. "Most of the health problems we see today are blamed on fat." Erasmus wants his work to shed light on the issue of low-fat diets.

"We have mostly been told, ‘Don't do this,’ and ‘Don't do that.’ It's time to hear ‘Do this.’ I'm saying, bring in the good fats and lower the bad fats," he said.

The American Heart Association is mainly responsible for the information promoting low-fat diets. AHA representative, Jennifer Pollzick, said that the guidelines are still recommending only a 30 percent total fat intake, despite nutritionists who dispute this recommendation.

“It is important to understand that we are not talking about each food item being 30 percent, or under, in calories,” she said. “The guidelines are for total calories over a period of time.”

If each food item eaten has to follow the 30 percent rule, many of the foods of a well-balanced diet would be excluded. For example, salmon gets 36 percent of calories from fat, and dark chicken meat without skin gets 43 percent of calories from fat. These food items can still be eaten, however, provided they are paired with other items that are lower in fat. It is the average of the foods eaten rather than the individual foods that should determine the 30 percent total fat intake.

The AHA also suggests figuring the average over a weeklong period. Some meals might be higher in fat while others are lower, allowing for variety as well as a balance of the foods eaten.

Kummerow feels that common sense mixed with knowledge should be the key to diets.

"People are bombarded with information and are spending thousands on diet foods and diets. Don't burden the energy system with high-fat, low-nutrient foods such as soft drinks, potato chips, french fries and candy bars. Eat fish or meat every day. Try to have six servings of fruits and vegetables. And sit down and have a meal with the family," he said.

He said that all the diets in the world won't work unless they appeal to the individual. He said simply, "In the end, people eat what tastes good to them."