Most public health guidelines including the Dietary Guidelines for Americans do not allow fat portions in excess. However, nutritionists and dieticians have agreed that they did not have all the fats in their diet. At present there is evidence to show that not all forms of fats are bad for the heart and some are indeed good for the heart .

Some of the fats may help to reduce triglycerides in blood. This is a particularly harmful type of lipid particle in blood that causes heart disease. Some fats can also raise the HDL or "good" cholesterol in the blood and thus protect the heart. As the HDL rises, the levels of the LDL cholesterol start to decline.

However all fat molecules are broken down in the body to provide high amounts of energy. Each gram of fat yields 9 calories . Fats are broken down into simple molecules containing hydrogen and carbon atoms. There are two major types of fats – saturated and unsaturated. Unsaturated fats contain carbon molecules binding to other carbon molecules while saturated fats contain carbon molecules binding to hydrogen molecules.

There are mono and polyunsaturated fats or fatty acids ( MUFA and PUFA ). MUFA have a single unsaturated carbon bond and are seen in good fats such as olive oil, some types of nuts etc. PUFA contain more than one unsaturated carbon molecule and are found in plant or vegetable oils, salmon and sardines, walnuts etc.

Stearic acid does not raise bad LDL cholesterol

Some of the saturated fats include "12-carbon lauric acid, 14-carbon myristic acid, 16-carbon palmitic acid and 18-carbon stearic acid". Among these stearic acid is not responsible for raising bad LDL in the body.

Researchers led by Heidi Silver, an associate professor of medicine at Vanderbilt University, developed a diet plan for 14 days. The menus contained three meals and two snacks in a day. The diet plan raises the total intake of "18-carbon monounsaturated fat, oleic acid and the 18-carbon and longer chain polyunsaturated fats".

These longer chain PUFAs are also called the omega-3 and omega-6 fatty acids . They replaced the carbohydrate snacks with nuts and croutons in the salads were replaced by slices of avocado. Salad dressings were made of canola oil, safflower oil and olive oil.

Fat consumption causes reduction in abdominal fat

This diet was advised to 144 women over a period of 16 weeks. This diet showed a significant reduction in abdominal fat and waist circumference in these women and there was also a 6 percent improvement in blood pressure markers.

The five and 10 year heart disease risk was also reduced by 6 percent among these women. The diet was appreciated and satisfactory for the participants.

The researchers then looked at the blood lipid profiles of the participants. They noted that the balanced moderately high fat diet showed more improvements in levels of triglycerides and LDL cholesterol among Caucasian females and significant rise in HDL levels among African-American females. Authors concluded that not all populations respond similarly to diets and diets need to be individualized for benefits.