Probably the most talked about and controversial of all the macronutrients.
No matter what is written about it, the undeniable fact is that we need fat.

Why we need fat

Fats supply us with the fatty acids that are essential for numerous chemical processes, including growth & development in children, the production of sex hormones, the formation and function of cell membrane, and the transport of other molecules into and out of the cells, finally fats are needed for the transport & absorption of the fat soluble vitamins A, D, E & K

Health Implications of too much
or too little fat

Getting the right amount of fat is a balancing act. Too much, and you increase the risk obesity, diabetes, heart disease and some cancers. Dietary trans fatty acids have an adverse affect on lipid level, by increasing the LDL (bad) cholesterol and decreasing the HDL (good) cholesterol. Too little fat and you are unable to absorb and use fat-soluble vitamins that smooth the skin, protect vision bolster the immune system and keep reproductive organs functioning.

All fats contain the same number of calories, about 250 an ounce or 9 calories a gram.
The average woman’s body is 20-25% fat by weight.
The average man’s body is 15% fat by body weight.

Good Fats vs Bad Fats

Not all fat is the same, and it is important to know the difference between the good fats and the bad fats.

The type of fat you eat is more important than the amount of fat you eat.
Highly saturated fats raise blood cholesterol levels, and with it the risk of heart disease.
Monounsaturated and polyunsaturated fats by contrast, either lower blood cholesterol or have no effect in it.

Unsaturated Fat

There are two types of unsaturated fat, monounsaturated & polyunsaturated. Studies have shown that mono & polyunsaturated fat appear to not raise LDL cholesterol. They also contain the essential fatty acids, Omega 6 & 3. These essential fatty acids reduce the risk of cancer, heart disease, Alzheimer’s disease; the list is growing year by year. The human brain is 60% fat, and one third of that should come from essential fatty acids.

Monounsaturated Fat

Monounsaturated fats are considered good guys because they do not increase LDL, bad cholesterol, and they do not reduce HDL, good cholesterol. They are predominately found in olive, canola & peanut oils, as well as avocado, nuts and seeds. Monounsaturated fats are liquid at room temperature and solid or semi-solid under refrigeration.

Polyunsaturated Fat

Polyunsaturated fat is high in the essential fatty acids, Omega 6 & 3. The human body is unable to self generate these two fats so it is essential that you obtain them from the foods that you eat. They help prevent blood clotting that can trigger a heart attack or stroke. They also help lower triglycerides, which can decrease your risk of heart disease.

Omega 3 are found in fatty fish such as salmon, mackerel, herring & sardines, as well as flaxseed, walnut & canola oil and some newer products as Omega 3 eggs. Omega 6 is found in foods that come from plant sources, Food sources include safflower, sunflower, corn oil, some nuts & seeds as almonds, pecans, Brazil nuts, sunflower seeds and sesame seeds.

Omega 3 provides alpha-linoleic acid
Omega 6 provides linoleic acid.
These fats should be eaten in moderation since they contribute to your total calorie intake.
Polyunsaturated fats are liquid unless hydrogen is added, in a process called hydrogenation.

Saturated Fat

Saturated fat comes primarily from animal products, meat, poultry, eggs & diary; the exceptions to that rule are coconut oil, palm oil & palm kern oil. A diet high in saturated fat can raise blood cholesterol level. Some saturated fat in the diet is important as it forms the cellular wall of each cell. Saturated fat is hard at room temperature.

The really bad guys...

Hydrogenated Oils & Trans fats

Hydrogenation is the process in which natural unsaturated oils, the ones that are beneficial to your health, are turned into unnatural, unhealthy trans fats. The more hydrogen is added to the oil, the more solid and dangerous it becomes. Fully hydrogenated vegetable oil is a hard waxy substance that causes damage to the artery wall.

The American Heart Association, AHA, strongly recommends these fat guidelines;

1.Limit total fat intake to less than 25-35% of your total calories each day.
2.Limit saturated fat to less than 7% of total daily calories.
3.Limit trans fat to less than 1%-the remaining calories should come from mono & polyunsaturated fat-these can be found in nuts, seeds, vegetable oil & fish.
4.Limit cholesterol intake to 300mg per day-if you have coronary heart disease or your LDL cholesterol level is greater than 100mg/dl or greater, limit your cholesterol intake too less than 200mg a day.

Information Sources

American Heart Association
Optimum Nutrition Bible- Patrick Holford
Premier Nutrition for Health and Fitness Manual
Good Fats Bad Fats- Rosemary Stanton PhD
How to Eat Move and Be Healthy- Paul Chek