Every cell in the human body requires fats for metabolic function.

The human body requires saturated fat for a variety of purposes, including the manufacture of many hormones, including sex hormones.

Just ask any woman who has suffered from anorexia nervosa, for example, about the hormonal effects experienced when she worked so hard at ridding her body of all body fat. She will tell you that her menstrual cycles and periods stopped altogether. Men, too, will face sterility issues if they lack dietary fat or have low cholesterol levels.

Some types of fats are important for antihyperlipidemia (they reduce triglyceride and cholesterol levels in your bloodstream.)

The right fats assist in lowering your blood pressure, thinning your blood and preventing blood clots.

Likewise, most inflammatory conditions can be prevented or controlled with regular Omega 3 fats in the diet. A lack of Omega 3 in your diet will intensify all manner of inflammatory conditions, ranging from asthma to arthritis and even heart disorders.

The human brain is 70% lipid (fats), and requires a regular intake of certain fats and cholesterol to function properly. Inadequate intake of these fats have been proven in many research reports to lower IQ levels, and are precursors to many mental illnesses ranging from short term memory loss and loss of concentration, through to depression, increased suicide rates, bi polar disorders and schizophrenia, and in the longer term, even Alzheimer's Disease.

Numerous essential Vitamins will not be absorbed by the human body unless accompanied by fats. These include the fat-soluble Vitamins A, D, E and K. No matter how many vitamin supplements you take, or how many vitamin rich fruits and vegetables you eat, if you have a low fat diet you will eventually suffer the degenerative diseases caused by vitamin deficiencies. Osteoporosis is one of the many of these degenerative diseases. Calcium requires the presence of Vitamin D to be absorbed in your intestines, and the presence of Vitamin K to "glue" it into your bone mass.

Animal fats also contain trace minerals. The human body is believed to require sixty different minerals for proper function and these must come from food sources. (Most "multi-mineral" supplements contain only ten to twelve minerals.) Many of these minerals required for proper cellular function are rare, so when available the body stores them in your adipose (fat) cells for later use. Eating animal fats therefore increases your intake of important yet often rare mineral nutrients.

If you observe a person who has maintained a low fat diet for an extended period, you will almost certainly note that their skin becomes dry and flaky. It is far more easily damaged. It loses it's elasticity. A low fat diet is the pathway to wrinkles and the "old age" look.

Scientific studies now confirm that certain fats act very similarly to anti-oxidants and are potent cancer fighters and preventers. Omega 3 and CLA - Conjugated Linoleic Acid, are your vital anti-cancer fats. (Admittedly it is equally true that certain fats can cause cancer.)

Your eyesight is very dependent in dietary fats. The single greatest cause of Macular Degeneration (a form of gradual blindness usually associated with age, and increasingly prevalent in western societies) is lack of Omega 3 oils in the diet. The eye's macular, when healthy, is coated with Omega 3 oil. In the absence of Omega 3 in the diet, other fats/oils take its place and degeneration of your eyesight and onset of blindness begins.

Both of the Essential Fatty Acids (Omega 3 and Omega 6) have functions for stimulating eicosanoids - hormone-like substances that boost the human immune system. If you have a low fat diet, and particularly if it is low in these two essential fats, your immune system will be compromised. (Important note - excessive Omega 6 produces the opposite effect.)

Insufficient Omega 6 fats in your diet will result in Diabetes. (It is important to note that Diabetes has other causes, too. Intake of Omega 6 does not of itself prevent diabetes from these other causes, and inadequate intake of Omega 6 fats is very rare indeed.)

The above list of the reasons you must have fats in your diet is not comprehensive, though should give you an insight into the importance of fats in your diet and the dangers of low fat diets.