Nutrition: Fats Chapter 12

Building a Body with Fat


Rethinking Fat

Fat definitely has an image problem. We look down on fat aesthetically. So much so, in fact, that we pay doctors billions of dollars each year to physically siphon out millions of pounds of fat from our bodies. We also look down on it biologically, as lazy, sedentary tissue produced by lazy, sedentary behavior. Sure, we understand fat in terms of extra fuel, but being a depot of stored calories in wait of a hungry day isn’t a very glamorous job in the bodily division of labor.

Fascinating Fat

That is changing. Fat has newfound respect, at least from scientists, who are learning that even the extra inches in our waistline are made up of very sophisticated and complex tissue. Fat in our body functions as an organ. Rather than just a passive or inert storage depot, fat is metabolically active and constantly communicating with other organs, including the brain, through a variety of hormones and chemical messengers. READ MORE

Moreover, the exact role fat cells play is influenced by the fat cell’s location in the body. In other words, fat cells in different parts of the body behave differently. For example, researchers have recently found that visceral fat, the fat that is deep inside the abdomen and wrapped around organs, seems to increase the risk of heart disease, stroke and diabetes. People with big bellies (the “apples”) typically have lots of visceral fat. How big is dangerous? Generally speaking, a waist circumference of more than 35 inches for a woman and more than 40 inches for a man will put those individuals at greater risk.

Individuals who might weigh just as much, but with the fat located mostly in their hips, thighs and rear ends (the “pears”) do not have this increased risk. Why? It isn’t clear, but it may be that the visceral fat is metabolically more active than thick layers of subcutaneous fat on the hips. LESS


Fats for Life

Fat Stores

Human beings seem engineered to be a fat species. An infant is born with about 5 billion fat cells and this number increases throughout childhood and adolescence to about 40 billion fat cells in an adult. And the difference between an adult who gains weight and an adult who stays lean is mostly the size of the fat cells, not the total number. Weight gain expands cells and weight loss shrinks them. If obesity begins in childhood, however, the number of fat cells increases as well and can approach 100 billion.

Brown Fat in Babies

One of the functions of fat is to provide insulation. That may not sound as important as it really is. Especially for babies. The insulating fat put on during the third trimester is an essential adaptation for a newborn. For a preemie, on the other hand, who doesn’t have the advantage of that fat, even a comfortable 72 F degree room can become be lethally cold very quickly. READ MORE

The control of body temperature, or thermoregulation, is so important for babies, in fact, that they have a very special kind of fat. It’s called brown fat because of its appearance and its job is to generate heat, which it does better than any other tissue in the body. Brown fat is brown because it is loaded with the iron-rich cellular powerhouses called mitochondria, as well as an extensive network of capillaries supplying blood.

Brown fat is found in the newborn animals of many species, as well as animals that hibernate. In a full-term human newborn, brown fat can account up to 7% of the infant's weight, and is concentrated in the back and nape of the neck, as well as around the heart, lungs, esophagus, liver and kidneys.

The reason that babies have brown fat is that they can’t shiver. As babies mature, they are able to rely more on physical methods of heat generation such as shivering and increasing their activity. With that development, brown fat gradually disappears.

Brown Fat in Adults

Compared to a baby, an adult has only a tiny amount of brown fat. In recent years, however, researchers have discovered that grownups have more of this special fat than was once thought. And furthermore, it appears that an adult’s brown fat can still play a significant role in energy consumption and weight regulation.

Cold temperatures seem to get brown fat working harder. Researchers have tested the idea, in fact, by keeping people in uncomfortably cold rooms and then having them put their feet in ice-water baths every hour. Maybe the next big weight loss trend, joke some researchers, will be frosty spas. LESS

The material on this site is for informational purposes only and is not intended as medical advice. It should not be used to diagnose or treat any medical condition. Consult a licensed medical professional for the diagnosis and treatment of all medical conditions and before starting a new diet or exercise program. If you have a medical emergency, call 911 immediately.