THE OIL INSIDE YOU

"I think the devil will not have me damned, lest the		
oil that's in me should set hell on fire" 		

   Shakespeare, The Merry Wives of Windsor.	
Act v, sc. 5, 1. 38.	 

Some years ago, say a few million, mankind had not yet discovered McNuggets (R) and Whoppers (R) and had to make do with whatever catches could be made during good weather. We survived those tough times by developing the ability to store fat as a reserve source of energy. This evolutionary change saved man from extinction. However, with excess storage of fat came many deadly diseases. Fortunately, the process of evolution is a continuous one and now that we donot need such high deposits of fat, help is on the way. Within the next few million years, the human race will not be faced with the dilemma of fighting the battle of bulges as our bodies adjust to the lower fat requirements. In the meantime, however, we must learn to live with our body fats.

Living with our body fats can be made easier, we have recently learned, if we incorporate some fish fat into our diet. Fish fat helps to rearrange, dissolve or otherwise neutralize other fats in the body. How this is done will be examined in this chapter.

WHAT IS FAT?

Fat, as we know it, is a greasy substance which ranges from cooking oil to a beer belly. Americans have a love-hate relationship with fat: they love to take almost 60 percent of their calories as fats but hate being overweight. Almost 80 percent of them are constantly striving to lose weight, most often fruitlessly.

Whatever your reaction to fat, you should realize it is essential to body functions, and in this context, is perhaps more essential than proteins and carbohydrates. The U.S. government classifies fat as an essential nutritional group; however, unlike other nutritional groups, there are no minimum requirements suggested since we always receive enough of it in our diets. Following are some of the important functions of fat in the body:

. Energy Source: Fat is the highest source of energy (about 9.5 calories per gram), giving twice as much energy as carbohydrates. The body stores fat as deposits to provide energy on demand. These deposits turn over frequently and are not stagnant tissues, as commonly believed. The carbohydrates and proteins convert to fat before they are utilized as sources of energy. Would you believe, there is no instant energy gained by taking a quick bite of a chocolate bar?

. Body Insulation: The fat under our skin and around the vital organs such as the kidneys, liver and womb protects against temperature change and injuries. It was the fat in our body that helped us survive the inclement weather when we used to live in caves and on top of trees. Several species, such as whales, still rely on body fat for survival. Traveling more than 5,000 miles, each way, from Alaska's Bering Sea to warm-water breeding grouds off Baja California, whales rely heavily on their fat deposits for nutrition and protection against weather. (The migration of 12,000 to 13,000 California gray whales each winter is an spectacular event. The two-month, 5,000 mile trek is the longest annual migration by a mammal. January, when the migration hits its peak, is considered the best month for whale-watching -- as many as 200 whales a day have been spotted off San Diego's coast line during mid-month. A whale-watching station at Cabrillo National Monument on Point Loma offers free access to a glassed-in observatory as well as to exhibits and a taped presentation about the whales' trek. For information call the Natural History Museum at 619-232-3821.)

Our body resists losing fat because of its essential purpose. Women, who have about 5-10 percent more fat than men, need it specifically during gestational and nursing periods.

. Chemical Storage: The fat deposits in our body often serve as inert reservoirs for many chemicals such as environmental pollutants, carcinogens and drugs to which we are frequently exposed. Without such storage ability, some beneficial drugs would have more dangerous side effects and have to be taken so frequently as to make them useless. Chemicals found in our environment are rendered less dangerous by this chemical storage because they are removed from circulation.

. Chemical Messengers: Body functions such as blood clotting, blood pressure, immunity against cancer and infections, inflammation etc. are all controlled by several chemical messengers synthesized from fats; examples include prostaglandins (PGs), leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs).

Given all these important functions, how can fat be bad? The answer is an old cliche: too much of a good thing can be bad. Now let's examine how this applies to our body.

HOW LEAN ARE YOU?

Before examining the bad effects of what is around our waist, let's figure out how much of it we carry around. The percentage of body fat is generally calculated by skin fold thickness and body density measurements; but the following simple equation should work for most of us.

			Percent fat = [90 - 2(height - girth)] 

The girth is measured at just above the umbilical level and the height is without shoes, both expressed in inches. Let us use this equation to calculate the percent of body fat in an 18-year-old who weighs 150 pounds, is 5 ft 2 inches tall and has a waist of 30 inches.

			Percent body fat = [90 - 2(62 - 30)] = 26%

The total fat in the body, therefore, is 0.26 x 150 pounds or 39 pounds, which is equivalent to 173,518 calories stored in the body, sufficient for about 115 days at the rate of 1,500 calories per day.

On an average, approximately 15 percent of body weight in men and 25 percent in women is made up of fat, corresponding to about 24 pounds of fat in men and 37 pounds of fat in women. The higher fat in women is necessary to provide for gestational and nursing requirements. In older age, the percent of body fat content increases as the lean muscles wither away.

How much fat we accumulate in our body depends on the number and the size of fat cells. Fat cells form early in life; after adolescence, the formation of new fat cells is quite limited. Therefore, if you were overweight at an early age, it was due to large number of fat cells, but if you picked up weight after adolescence, it was due mainly to the growth in the size of the existing fat cells. This explains why it is more difficult to rid yourself of childhood obesity.

Adult obesity is more responsive to weight reduction by dietary measure and is much easier to control. The word "easier," however, is a relative one. Those of us who have weight problems know that it is anything but easy to lose weight, despite the plethora of gadgets, gizmos, potions and therapies available to us.

There is no doubt that being overweight causes many diseases, especially heart diseases and cancer, but it is difficult to assess what is the right amount of fat for one person, because of the differences in the metabolism of fat in individuals and how it causes diseases. Most height-weight tables are at best a crude indication of what your weight should be since they do not take into account the high variability in the effect of weight on body functions. The current medical findings show that being slightly overweight is more healthful than being very lean.

As W. S. Gilbert said in "Iolanthe," act I, "I see no objection to stoutness - in moderation."

The havoc fat wreaks on our physical health is, perhaps, minuscule compared to what it does to our mental health. Only about 8 percent of American elementary-school-age girls are overweight but more than 80 percent of them are on some type of weight loss program, causing severe nutritional imbalance and leading to such diseases as bolemia, nervosa anorexia and suicidal tendency. The word is out: fat is ugly. Historically, this was not the case. During the Renaissance, for example, pleasingly plump bodies drew great admiration. Food has now become so abundant and cheap due to the technological revolution that eating is no longer only a rich man's indulgence. Consequently, the plump body is no longer in vogue

INSIDE FAT MOLECULES

The fat in our food is mostly composed of molecules called triglycerides, which are made up of three fatty-acid and one glycerol molecule as shown below (Fig. 1.1).

Figure 2.1 Structure of triglyceride or fat molecule.

Fatty acids are classified as saturated or unsaturated depending on the number of hydrogen atoms they contain (Appendix A-1 & A-2). The unsaturated fatty acids are further classified as omega-1, omega-2, omega-3 and so on, based on where the first unsaturation appears, counting from the terminal carbon (Appendix A-3). Most vegetable sources have omega-6 whereas fish oil contains mainly omega-3 type fatty acids. Such small difference as the omega position is crucial in determining how beneficial or harmful these acids are to the body.

Three unsaturated fatty acids, namely arachidonic, linolenic and linoleic, comprise a group of "essential fatty acids," or vitamin F. A minimum amount of vegetable fat is, therefore, important in the diet to provide an adequate supply of these essential fatty acids since the body cannot synthesize them. The minimum dietary requirement is that 1 percent of the total calories in adults and 4 percent total calories in children should be provided by these essential fatty acids. These requirements are easily fulfilled in our daily diets.

The essential fatty acids perform several vital functions such as controlling plaque formation and blood pressure and promoting the body's defense against cancer and infections. The deficiency of essential fatty acids in the body results in retarded body growth, scaly or broken skin and excessive water loss from the body.

The physical and chemical properties of fats determine health hazards. One such property is the liquidity of the fat at room temperature. Saturated fats appear solid at room temperature (or have high freezing point), whereas unsaturated fats generally stay liquid at room temperature. If unsaturated oils are hydrogenated, such as in the prepartion of maragarine, the oil turns solid. As a rule of thumb, liquid fats are less hazardous to health than solid fats.

The omega position, in unsaturated fats, has significant effect on the freezing characterstics. Generally, omega-3 acids freeze at much lower temperature than other omega acids giving the oils containing these acids different characterstics (Table 2.1).

TABLE 2.1
FREEZING TEMPERATURE AND SATURATION OF OILS

s = solid at room temperature

THE LIPIDS

Fats in the blood are comprised of triglycerides, fatty acids and several other "fat-like" chemicals such as cholesterol, some hormones and vitamins, all of which are collectively termed LIPIDS. The lipids, because of their immiscibility with blood, cannot stay suspended in it any more than a tablespoonful of oil added to a glass of water would. Therefore, to provide mixing of lipids in the aqueous blood, the body coats the fatty substances with water soluble proteins making a variety of other water insoluble chemical forms.

These fatty balls with a water miscible exterior, called lipoproteins, stay dispersed in the blood and are carried around to wherever they may be needed to supply fat, hamones and vitamins. The percentage of proteins in lipoproteins, which ranges from 1 to 99, determine how heavy these fatty balls are (appendix A-4) compared to water and what their size is. The heavier balls, called high density lipids are smaller diameter because of their compact nature.

Generally, the low density lipids contain large quantity of triglycerides and cholesterol and are much more harmful in causing blocking of arteries than the heavy density lipids; this concept which will be elaborated in later chapters.

The concentration of lipids in blood as found in healthy individuals is listed in Table 6. It is important to know when you blood becomes "fattier" or shows too much of a wrong type of lipids.

TABLE 2.2
LIPIDS OF BLOOD, MG/100 ML
Lipid Mean Rangs

Lipids in the blood pose a serious threat to health, causing blocking of arteries, stroke and even cancer. It is, therefore, inportant to monitor them closely. The following chapter examines the actions of lipids and how they can be modified to ensure better health.