Body Fat 101

Although many people have a hate relationship with their body fat and would like nothing better than to get rid of all of it, a certain amount is essential for our bodies to function properly. This ‘’essential fat’’ is found in the marrow of the bones, in the heart, lungs, liver, spleen, kidneys, muscles, and throughout the central nervous system.

Women need at least 10 to 12 percent of their body weight to be composed of essential fat while men need 2 to 4 percent. Women have a higher requirement because of the demands of childbearing. Although some women are exceptions, menstruation and ovulation usually stop when a woman’s body fat drops below 15 percent.

Storage fat
The rest of the fat in your body is called ‘’storage fat’’. It is located around internal organs (internal storage fat) and directly underneath the skin (subcutaneous storage fat). Storage fat acts like a shock absorber to protect your bones and internal organs from jarring impact, works as an insulator to conserve body heat, and serves as a fuel depot for your energy needs.

In theory, approximately fifty percent of storage fat is underneath your skin and the other fifty percent is stored internally. However, this ratio is not the same for everyone and it changes as you get older.

What is a normal body fat percentage?
A normal body fat percentage range for the average woman is 18 to 26% of body weight, while a normal range for a man is 9 to 15%. This includes essential and storage fat. However, to accommodate all fitness levels and ages, the American Council on Exercise believes that women can be between 14 to 31 percent body fat and still be considered “healthy” while can men can have a range of 6 to 25 percent.

Women are naturally ‘’fatter’’ than men.
Past studies of two American migrant groups (the Donner Party and the Willie Handcart Company) that were stranded in mountain blizzards in the mid-1800’s show that more men than women died. The researchers believe that it was a higher body-fat percentage that protected the women.

Due to a higher fat percentage, a woman is naturally softer than a man. To expect a woman’s body to be as lean and as muscular as a man is to go against nature’s design. Even at 20 percent body fat, some areas of a woman’s body will have extra fat.

Covert Bailey, author of ‘’Fit or Fat’’, observes that ‘’healthy women do jiggle’’. He writes, ‘’The buttock and thigh muscles may be quite firm, but most women, unless they are very young or have inherited thin legs and hips, carry a wiggling layer of fat in that area. Even super-athletic women – those who play professional tennis or run marathons – are not as solid in the hips and thighs as their moderately active male friends – this is simply part of being a woman.’’

Fat distribution patterns.
Fat is not distributed equally throughout the body. It is different for men and women. Men tend to store most of their fat in their trunk and upper body while women have most of their fat in their lower abdomen, hips, thighs, and buttocks. These differences in fat distribution show up during adolescence. During childhood, boys and girls have the same body structure.

According to Vivian Heyward, author of a 75-study analysis of body fat testing methods, there are known ethnic differences in fat storage. Native Americans, Asians, Blacks and Hispanics tend to deposit more fat on the trunk than on the extremities and have more upper-body subcutaneous fat than Whites.

When fat cells are made.
Fat cells are made most rapidly during specific times – the last three months as a fetus until about 18 months of age, between the ages of four and seven, and during early adolescence. After that, fat cells only increase or decrease in size depending on whether you gain or lose weight.

However, if you become significantly overweight, you can develop new fat cells because there is a limit to how much your existing fat cells can enlarge. Another “danger” period is during the last three months of pregnancy when studies have proven that new fat cells can be made if a woman gains excessive weight.

A normal weight person has about 25 - 35 billion fat cells while a person who has been overweight since childhood can have anywhere from 50 to 100 billion. A severely obese person can have as much as 270 billion fat cells!

Research indicates that a person who has more fat cells will have a harder time losing weight than a person with fewer fat cells. This highlights the importance of preventing childhood obesity since childhood is the time when the most fat cells are created.

Fat cells behave differently.
A fat cell has been described as a “tiny plastic bag that holds a drop of fat”. It was previously thought that all fat cells had the same function – to passively store and release energy.

Scientists now believe that fat cells have different biochemical receptors or triggers. They have identified two kinds of receptors – alpha-receptors, which cause the storage of fat; and beta-receptors, which cause the release of fat. And wouldn’t you know it? The fat cells in the hips, thighs and buttocks have more fat-retaining or alpha-receptors while the fat cells in the abdomen tend to have more beta, or fat-releasing, receptors.

Scientists have also found that hormones influence these receptors. Male hormones tend to trigger the beta or fat releasing, receptors, while female hormones tend to stimulate alpha, or fat-retaining, receptors. This explains why hip and thigh fat is so stubborn to remove.

Individualized weight loss patterns.
We all respond differently towards an exercise and weight loss program because of different factors affecting our fat cells and fat distribution patterns. A wife should not compare her weight loss with her husband who will probably have an easier time losing fat in his belly. Two friends who are trying to lose weight together cannot expect similar results because one friend may have more fat cells that developed during childhood.

Next week: The two different kinds of abdominal fat.