Chapter V

A Look at Fat and Your Body

The physician indicates the type of fat that can be helped by liposuction.

Athletes tend to have considerably lower proportions of body fat. For example, world-class marathon runners may have as little fat as 6 to 8 percent of their body weight.

If you are overweight, however, your proportion of body weight composed of fat may be substantially higher than the average for your sex. In extreme cases, adipose tissue-the technical term for the layers of fat in your body-can increase as much as a thousandfold. That's why you read about unusual men or women who weigh as much as 900 lbs. or more.

1. The doctor shows how this patient's contours are marred by fat deposits.

2. The "pinch test" illustrates fat deposits beneath patient's arms on back of torso.

Not all fat is the same, however. Your body contains two kinds of fat cells (called adipocytes): brown fat cells, and white fat cells.

Researchers believe brown fat is not the type of fat that causes adult obesity. They think brown fat is significant because they believe it is responsible for keeping our blood vessels and internal structures at the "right" temperatures. Most of the brown fat in our bodies lines the outside walls of blood vessels, the heart, and vital organs. The brown fat plays an important role in creating and dissipating (getting rid of) heat. You may want to think of it as a sort of insulating jacket that surrounds the larger blood vessels and helps to regulate the temperature at which the blood circulates through them.

The brown fat found near these blood vessels is not the fat that is found almost immediately under your skin and makes you look fat.

Perhaps brown fat is connected to survival in cold climates. For example, the heat which brown fat generates enables hibernating animals to maintain a temperature high enough to sustain life.

Human beings seem to have more substantial amounts of brown fat (in proportion to total body weight) in fetal life. Perhaps-and no one is sure-the much higher proportion of brown fat in a fetus insulates the walls of its blood vessels and thereby protects the extremely vulnerable fetus from the more severe effects of a change in temperature. Brown fat seems to generate heat from the "burning" of fat from the many tiny fat globules inside each brown fat cell.

As a person matures, the brown fat that surrounded the vital organs in the abdomen slowly diminishes. By the time you are an adult, very little of the brown fat remains. In most adults, the small deposits of brown fat remaining deep inside their abdomens are unaffected by the normal state of their nutrition.

1-3. Bulges of fat on hips, arms, thighs are indicated by the "pinch test."

4. Excess fat is apparent in the "pinch test."

White fat cells, however, are quite different. They are the fat cells removed during liposuction. White (actually, a sickly, pale yellow) fat deposits respond readily to the state of your nutrition. If you eat too much-even a small amount too much-you can trigger the transformation of the excess food into fat. This fat is carried by your blood into each and every fat cell of your body, and stored inside these tiny white fat cells. You can easily understand that it does not take a long time for fat to accumulate inside each fat cell; in fact the cells grow in size to store the fat.

In addition, there are certain parts of our bodies where "white fat cells" seem to accumulate much more fat, and at a faster rate than in other body parts. Most noticeably, these areas include the "love handles," the abdomen, the hips, the thighs, and the buttocks. In some cases, male breasts are enlarged with fat deposits, causing much embarrassment to those men plagued with the condition.

As we will see later, white fat deposits accumulate mainly under the skin. They can also accumulate in the abdomen, among the sheets of tissue which support the intestines. Unlike the brown fat cells, these white fat cells cannot burn their fat. Instead, they serve primarily as energy deposits. The globules of fat-also called lipids-inside each cell are available for conversion to energy as it is needed, and can be used by other tissues in the body.

SOURCE OF ENERGY
Since fat is really a concentrated fuel, it is the body's most efficient energy storage system. Each gram of fat yields nine calories, while each gram of protein or carbohydrate (starch, sugar, or glycogen-a form of carbohydrate stored in your liver and muscles--yields only four calories.

Your primary source of energy is glucose, a simple sugar that your bloodstream carries to every cell in your body. As part of your normal digestive process, glucose is produced from the food and drink you consume.

1. The doctors fingers indicate flabby skin and fat under patient's chin and on neck.

2. Center, above, shows bulging hips and abdomen, with protruding navel.

3. Another typical site of fat deposits, at saddlebag area.

The glucose in your bloodstream, however, doesn't last very long. When you go four or five hours without eating, the level of glucose in your blood (often called "blood sugar") begins to drop.

The body has a second source of energy, or alternate fuel, called glycogen. It's stored in your liver and muscles. Glycogen can provide you with energy. But you don't have much glycogen ...only enough, if you aren't eating, to provide you with energy for one or two days.

Your third source of energy, or alternate fuel, is your fat.

Unfortunately, your body tends to transform any excess energy to fat, rather than to glycogen. There are relatively small amounts of glycogen stored in your liver and muscles, but there can be a great deal of fat stored in your body-a fact most of us know only too well.

Densely packed deep in the body and under the skin, fat supplies energy more efficiently than any other fuel. The average adult has 2000 to 4000 calories of glucose stored in his body--a supply sufficient to last one or two days. However an average adult, who is not even overweight has something like 150,000 calories of fat stored in his body. It is not uncommon for overweight people to have as many as 300,000 to 500,000 calories of fat stored in their bodies. Such an amount of fat can support life for anywhere from two to four months...and explains why a plane crash survivor, downed in Alaska, was able to exist with little or no food, even though several months passed until rescue.

Realistically, however, the human ability to store energy in the form of fat is unnecessary today for those of us who live in a food-abundant society. Long ago, however, it was an important survival advantage.

Before human beings settle down to domesticate animals and raise crops, before civilization in other words, this energy stored in the form of fat enabled human beings to live through frequent periods of famine that we think were common in pre-historic times. Having a substantial amount of body fat was crucial during droughts, floods, earthquakes, volcanic eruptions, severe winters, and other calamities which caused shortages of the food supply.

Stored fat enabled human beings to travel long distances, even though the food supply was scarce or uncertain during the journey. Anthropologists tell us that primitive voyagers of the South Pacific would deliberately gorge themselves for weeks before setting out on the ocean in their small vessels. The fat on their bodies provided them with the energy needed to maintain life, long after whatever food supplies they took with them had been exhausted.

FAT STORED BEFORE BIRTH
Survival seems to be the driving force behind the body's storage of fat, even before birth. Researchers have found fat deposits in human fetuses which were between 26 weeks and 30 weeks of gestation (normal full-term pregnancy is approximately 40 weeks.) They have also found evidence which indicates that the human fetus manufactures its own fat while inside the uterus. The average newborn arrives with more than a pound of fat it has made itself--not just absorbed from its mother's body.

FAT STORAGE IN THE ADULT
As an adult, the fat in your body is stored as lipids inside the white fat cells (adipocytes). It has been deposited there by the blood. Your bloodstream picks up the fat in two ways: either as tiny droplets, called chylomicrons, from the digestive system after a meal; or as lipid-protein complexes, from the liver. These lipid-protein complexes, called lipoproteins, are made up of a specialized form of protein molecules that clump together, combined with cholesterol and triglycerides.

Whether the fat is composed of chylomicrons or lipoproteins, the bloodstream picks it up and brings it to the outside of the fat cells. Next, these substances must be broken down into fatty acids before they can be transported through the outside wall of the fat cell. A special enzyme, or catalyst, called lipoproteins lipase (LPL), is manufactured by the fat cell membrane and accomplishes the breakdown.

FAT CHANGES AS YOU GROW OLDER

* INSERT IMAGE 5-12

1. Above, front and side views of normal adults show contours of bodies without deposits of excess fat.

As a person grows, matures, and ages, there seems to be a series of predictable changes in how the body handles fat. Although individuals may vary slightly, the pattern is generally consistent.

Researchers believe the number of fat cells in the human body grows rapidly between birth and about age 2. From that time until just before puberty, the number of fat cells increases very slowly, in fact, during this "latency" period, it remains almost stagnant.

As part of the changes that precede puberty, the number of fat cells again increases rapidly.

Once maturity has been reached, the number of fat cells seems to be permanently fixed. In other words, researchers believe you have approximately the same number of fat cells when you are 27, or 38, or 43 as you did when you were about 15 or 16. The latest findings indicate that this is achieved by changes which affect the chromosomes of fat cells. Certain molecules are thought to behave like "gate keepers," and to keep the fat cells from reproducing.

If this theory is true, then how do adults get fatter?

Researchers agree the size of each individual fat cell increases. Each of the cells expands-to many times its original size-to store the body's excess energy.

GENETIC DIFFERENCES IMPORTANT
The places in which the fat cells are located--the places, in other words, where clumps of fat cells make you bulge unattractively--seem to be determined by your heredity. One woman may find she has prominent saddlebags, while a friend may be agonizing over a protruding abdomen. In a family I treated in which two sisters were patients, Marybeth reported she was always considered heavy in the hips, while Elaine had problems with her thighs. Because no two of us (with the exception of identical tvans) are completely alike in our genetic makeup, we differ as to the number of fat cells that are genetically predetermined for each of our body parts.

SEX ALSO PLAYS A PART
Nutrition experts are starting to conclude that there is a difference in the way in which men and women handle food. Although research studies such as those being done at Medical University of South Carolina in Charleston are continuing, the bottom line seems to be that it's easier for women to put on weight than men, and harder for them to lose, even when calorie count for diet is identical.

*INSERT IMAGE 5-13

1. The chart shows female bodies, with contours showing the deposit of excess fat which typically occurs at various ages throughout life.

*INSERT IMAGE 5-14

2. The chart shows the typical deposits of fat in the male body as aging occurs, from toddler, teenage years, young adult, middle age. and older years.

Mature men have a leaner appearance than mature Women, even at ideal weight and body composition. Physicians believe the ideal percentage of body fat for men is approximately 12 to 15 percent. For women, it's approximately 20 percent; and up to 22 percent is medically acceptable.

FAT COMES WITH AGE
From the age of 35 or so onward, both men and women tend to become fatter. Two factors seem to be responsible. First, of course, is simply eating too much. We are constantly being bombarded with advertisements and reminders of how delicious foods taste. The modern supermarket is crammed full of suggestive displays. Whether it's the produce department (watermelons, canteloupes, berries of several kinds and colors, oranges, grapefruits, tangerines, bananas, avocados, and apples-to name only a few fruits) to the dairy department (milks, cheeses, fruit-flavored and plain yogurts) to the frozen dessert case (cakes, pies, ice creams in various flavors), the supermarket offers the susceptible American consumer a nearly infinite number of choices.

Consequently, it is all too easy to take in more calories than we expend in energy. It's something like continuing to deposit money in a savings account. Instead of becoming wealthy, however, we are accumulating unwanted fat.

For every 3500 calories you eat that you do not "burn off," you add one pound of weight. Although not all that weight is added to your body as fat, a good percentage of it certainly is.

The other factor which tends to make us fatter as we grow older is that metabolism-the chemistry of our bodies-changes. We lose lean tissue and exchange it for fat. Even if your weight stays constant, this change occurs.

As we look at fat cells more closely in the next chapter, you will begin to understand the aspect of fat which makes liposuction possible.