Fat is a word that most of us do not want to hear on a regular basis, especially when it relates to our own bodies. We associate fat with growing beer guts, tighter pants, and less-than-ideal sex and social lives.

However, fat plays a critical role in many of the processes our bodies go through each and every day, and it has both positive and negative sides.

This three-letter-word has more secrets than you know...

1. Fat cells can swell to as much as six times their minimum size

When you consume more calories than you burn off, fat cells in the body swell to as much as six times their minimum size, and they begin to multiply — from 40 billion in an average adult up to 100 billion. Everyone has fat cells; they begin to form and take shape before birth. Around the age of 16, the body's fat cells are mature, and then lifestyle and genes play a role in gaining or losing weight as you age.

Fat cells are critical for survival and help assist the body's "store and management" energy system. Simply put, fat that is not used for fuel immediately is stored for later use. To that end, if you're eating high-calorie meals every day and not burning very many calories, your fat cells swell and multiply, resulting in weight gain.

2. Fat cells secrete extra estrogen

Carrying a few extra pounds may also wreak havoc on your hormonal balance, leading to a variety of illnesses and health risks. Estrogen, the classified "female hormone," is a fat-storing hormone that is also naturally present in small amounts in men. But when you gain weight, estrogen levels rise and other health problems ensue.

Although estrogen is necessary in men, as it regulates a healthy libido, improves brain function (especially memory) and protects the heart, when the levels are too high, testosterone levels are reduced, and many men experience fatigue, muscle tone loss, decreased sexual function, and in some cases, enlarged prostates. In other words, there are no good side effects to increased estrogen levels in men.

3. If you lose a lot of weight, your fat cells shrink, but they do not disappear

Having 100 billion fat cells in your body from weight gain may sound scary. The good news is that you can still lose weight after your fat cells swell and multiply; in fact, when you lose weight, your fat cells shrink. Although their total number only decreases slightly (if at all), the cells become less metabolically active and remain in your body, waiting for you to pick up a bag of pork rinds so they can expand again.

This means that it's better to try to maintain a normal weight than to gain and lose weight on fast, "quick fix" types of diets. Someone who has maintained a normal weight (i.e. has been relatively thin) all their life will have an easier time staying at that weight than someone whose fat cells have swelled and multiplied.

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4. Fat tissue attracts cells that promote inflammation

Aside from the lousy way you feel when you're packing a few extra pounds, there are also internal complications that result from excess fat.

Fat tissue attracts immune system cells called macrophages that promote inflammation in the body. So, if you are carrying any extra fat, your body begins to produce an immune response similar to the reaction your body exhibits when you develop the flu or have an injury.

Inflammation's intended purpose in the body is to fight infection. Therefore, your body sees the extra fat calories that you consume from fried calamari and greasy pizza as an invasion in the body.

But don't worry: You don't have to give up your favorite foods just yet. Studies show that decreasing your total body weight by as little as 10% (if you're overweight) can improve your health and limit the immune response that your body exhibits from the extra weight.

5. Fat cells behave differently in different parts of the body

Men typically carry excess weight in the midsection; thus, if you gain weight (whether you drink beer or not), most of it will go directly to your gut first.

Belly fat increases the likelihood of bad cholesterol (LDL), triggers extra fat in the bloodstream, and raises blood pressure and blood sugar levels. Furthermore, abdominal fat tends to be deeper inside the body, as opposed to hip or thigh fat, which is stored directly under the skin.

Fat cells within the abdomen are metabolically more active than fat cells located in other areas of the body. They release more fatty acids, which can lead to diabetes, coronary artery disease, stroke, and certain cancers. Abdominal fat cells may also affect the healthy functioning of the liver.

Unfortunately, there is no way to target weight loss in one specific area of the body (i.e. your abs). So, in order to lose your spare tire, you must exercise your entire body. The good news is that excess weight in the midsection is usually the fastest to come off during regular exercise.

6. If you consume no fat at all, you will short-circuit your body

If you avoid consuming any fat, you will short-circuit your body's natural system for transporting vitamins through the body and regulating cholesterol levels.

As noted above, fats are critical for maintaining your body's natural processes, such as vitamin absorption and energy production. Without these particular fat-soluble vitamins (A, D, E, and K), the body cannot suitably absorb calcium, hormone production may be negatively affected, and blood may have difficulty forming and/or clotting properly.

A lack of fat-soluble vitamins can lead to serious health problems, including night blindness, rickets, anemia, and internal bleeding. Furthermore, when the body cannot absorb calcium, bones can become weak and brittle.

Fat — the unsaturated type — can also play a role in regulating cholesterol by lowering your "bad" (LDL) cholesterol levels.

7. Fat calories should only be 30 percent of your total daily calories

Despite all of its secrets, fat is not the enemy. A certain amount of fat is needed to maintain the normal functioning of your body's internal processes. Fats aid in the absorption of certain vitamins, and above all, they provide your body with the energy it needs to function every day.

A healthy diet should take approximately 30% of its total calories from fat. However, keep in mind that fat contains twice the number of calories of a carbohydrate or protein, and that different fats are considered "healthier" than others.

Saturated fat, which is derived from red meat and dairy products, tends to raise bad (LDL) cholesterol levels more than other types of fat, such as monounsaturated and polyunsaturated fats found in nuts, olive oil and fatty fish.

Saturated fat has also been linked to abdominal obesity, as has trans fat, which is found in many processed foods.

Coexisting With Fat

Despite its ugly reputation, you can have a healthy relationship with fat and maintain a lean body. Here are some tips:

— Choose "healthy" fats (olive oil, nuts and fatty fish) and bypass the obvious "bad" fats (fried/fast food, baked goods and sugary soft drinks)

— Steer clear of processed foods and eat animal products (meat and dairy) in moderation

— Watch your abs — if you're belly has started to resemble the spare tire sitting in the trunk of your car, get to the gym!