Childhood Obesity Chapter 3

Fat: What Is It Good For?


What Does Fat Tissue Do?

Adipose tissue (fat tissue) is a type of connective tissue. The two main types of adipose tissue in humans are subcutaneous (under the skin) and visceral (inside the abdomen).

Adipose tissue performs many functions in your body. Its main job is to store energy in the form of lipids (triglycerides and cholesterol). When you eat fatty foods, often there are more lipids than you need for energy at that time. The excess lipids are stored in your adipose tissue. The same holds true for proteins and carbohydrates—when you eat more of them than you need immediately, excess amounts are converted to lipids and stored in adipose tissue for future use.


What Are Fats Used for in the Body?

Fats are a type of lipid. Lipids are our major fuel reserves. They are very efficient at storing energy: a single gram of fat stores about 9 kcal per gram, whereas a gram of carbohydrate or protein stores only about 4 kcal. Such a concentrated form of stored energy means there’s less bulk to carry around, and it also enables us to survive for long periods of time without eating. A normal body is about 20% fat. That’s enough stored energy to enable someone to go without food for 20-30 days. READ MORE

About 80% of adipose tissue is composed of lipids. If you look at a fat cell under a microscope, it looks as though it’s almost empty. In fact, most of the space in the cell is taken up by the lipids, which push other parts of the cell (like the nucleus and cytoplasm) to the cell’s edges. The large lipid content of the cell makes fat a good cushion against impact, helping to protect the body’s organs. And because lipids are very poor conductors of heat, fat tissue is an excellent insulator. LESS


Females and Fat

Women and men store fat in different places. Men tend to carry weight on their chest, abdomens, and buttocks—they’re “apples.” Women, on the other hand, tend to carry fat on their breasts, hips, waists, and buttocks, making them “pears.” The difference is determined by the hormones estrogen and testosterone at puberty. Puberty is also the time when the number of fat cells you’ll have for the rest of your life is set. Fat cells are generated in the developing fetus and also at puberty, but normally aren’t generated after that. When you store more fat, the fat cells increase in size, but not in number. (The exceptions are if you gain a large amount of weight or if you have liposuction.) READ MORE

If you’re a woman, it’s probably not news to you that you can consume fewer calories than a man and still put on more weight than he does. Researchers think this is due to the female hormone estrogen, which reduces the ability to burn energy after eating. Women store fat more efficiently than men, most likely to prime them for childbearing. LESS


Fat Is an Organ

For many years body fat was thought to be a mostly dormant substance with a mainly passive function, that of storage. But now researchers have found that adipose tissue is, on the contrary, highly active. Scientists have identified about 80 different proteins produced by fat cells. Adipose tissue has a metabolic function and acts as an endocrine organ—that is, it produces hormones and secretes them into the bloodstream, through which they travel to affect organs all over the body. In fact, fat tissue produces literally dozens of hormones, including leptin, which controls appetite, and adiponectin, which affects insulin sensitivity and blood sugar levels. READ MORE

Fat cells are also important contributors to the immune system and its inflammatory response. Among other substances, fat cells manufacture cytokines, proteins that affect cell signaling and behavior. They include interleukins, tumor necrosis factor, and interferons, which trigger inflammation and respond to infections.

Because adipose tissue is now known to be so biologically active, researchers think that it could well play an important role in cardiovascular disease, diabetes, cancer, and other diseases. LESS

Photo credit: Boy running
Copyright 2009 Erick Söderström

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.