One major enemy of the Western world does not come in human form. Rather, it is a substance, an energy component, that many spend their lives trying to rid themselves of. At once considered a health concern and a necessary health component, this substance, fat, which comes in various forms and compositions, is on the minds of many as they begin their day.
Much of big businesses commercial success hinges on fat removal for health and aesthetic reasons. New and innovative diets and training regimens designed for the express purpose of reducing its deposition are springing up almost daily, such is its reputation as a health concern and the implications it has for all who posses excessive levels.
With such an emphasis on fat reduction between much of the world's industrialized population and with all the coverage it receives in various media, there seems to be a surprising lack of insight as to exactly what it is and why we at turns need a certain amount, but not an oversupply.
While many know what body fat is in its more obvious problematic form, few have a detailed understanding of what its purpose really is. So why do we have body fat and exactly what is this, often-unsightly substance that, if maintained at an appropriate level, can be crucial for survival, health and wellbeing?
In this article I will discuss body fats composition and why it is needed, how it distributes itself, why some possess excessive levels and what can be done about it.
What Is Body Fat, What Are Its Problems & Why Do We Need It?
What Is Body Fat?
Stored body fat in its most easily recognisable lumpy form - the type that contributes to obesity if accumulated in significant quantities - is made up of free fatty acids liberated from various lipoproteins (a lipoprotein is a chemical compound made of protein and fat, that transports lipids around the body to perform various biological functions).
Once liberated, these fats if not used as energy, will be stored in adipocytes (commonly referred to as fat cells), which form the composition of adipose tissue. From there they are assembled into triglycerides to be stored for future use. When we refer to body fat we are talking about adipose tissue and its lipid containing adipocytes.
Adipose tissue is primarily situated beneath the skin, where its main role is to store energy in the form of fat. Depending on its quantity and deposition, this stored fat can be good or bad.
What Are Its Problems?
On the downside, fat cells have been shown to play a role in determining insulin resistance. A large accumulation of abdominal fat (or central obesity) is viewed as an important marker of diabetes as, due to its specific metabolic profile, and given it can prevent a normal insulin response, it is more prone to impaired glucose tolerance, a state that often leads to full-blown diabetes.
Diagnosed by measuring the hip to waist ratio, central obesity (which can be confirmed if the waist measurement exceeds 1.0 in men, or 0.9 in women) also contributes to the expression of Resistin, a hormone that is thought to suppress the ability of insulin to stimulate glucose uptake in fat cells, thus potentially linking obesity to diabetes.
In addition to its influence on insulin response, central obesity is also considered a major risk factor for high blood pressure and heart disease, making it something to be avoided at all costs.
In fact, topping the list of combined factors which may result in "metabolic syndrome", or an increased risk for both heart disease and diabetes (type 2), is waist circumference - for men a measurement of 40 inches or more, or for women 35 inches, will significantly increase their chances of getting metabolic syndrome.
An additional concern for those who possess excessive fat is its potential to produce the enzyme aromatase. Adipose tissue is the greatest peripheral source of the aromatase in both males and females and it has been shown, in some cases, to advance breast cancer, although its principal function is to transform androstenedione to estrone and testosterone to estradiol, thus increasing estrogen levels.
Excessive estrogen can contribute to several health problems, including the aforementioned breast cancer (as in women who are estrogen-dominant it may cause rapid growth of cancer cells), risk of heart disease and stroke, baldness, obesity (which can cause a vicious weight-loss cycle) and reduced sexual appetite, not to mention the diminishing of testosterone, which has many beneficial functions such as fat reduction and muscle and bone growth.
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Why Do We Need It?
While it is obvious that surplus fat can contribute to a raft of health problems, several of which are mentioned above, at acceptable limits it can be advantageous. An acceptable level of fat (defined as between 18 and 24 percent for men and 25 to 31 percent for women, according to the American Council on Exercise) can promote favourable health conditions.
According to Zhaoping Li, M.D., director of clinical research at the UCLA Center for Human Nutrition, "Fat cells are not as passive as physicians once thought. It has been widely accepted that fat tissue doesn't merely store fat but, rather, is an endocrine organ that secretes hormones to regulate appetite, insulin sensitivity and body weight1."
Hormones leptin, which acts on the hypothalamus to suppress appetite and burn fat stored in adipose tissue, TNF (Tumor Necrosis Factor), which controls the production of pro-inflammatory molecules, and helps cells heal or repair, and the prostaglandins (hormone-like substances), which regulate many of the body's functions, are examples of the beneficial molecules liberated from fat.
One who has an acceptable level of body fat will produce sufficient quantities of these hormones, whereas obese people, as mentioned, produce hormones that encourage the accumulation of body fat.
Triglyceride & Free Fatty Acid Levels:
Fat cells also play an important role in maintaining triglyceride and free fatty acid levels, the former being the chemical form in which most fats exist, the latter the components of triglycerides (fatty acids and glycerol) that are released into the blood to provide energy (these fats can yield relatively large quantities of ATP, the body's energy molecule).
Therefore, one who has a ready supply of triglycerides, not an excessive amount, will have an additional energy reserve. Fat as energy is often viewed as being one of the more efficient sources. As fat initially contains very little oxygen - it can combine with more oxygen to produce a longer lasting fuel source.
Additionally, and belying its ability to provide long-term energy, it is stored in the average person in comparatively smaller quantities. To illustrate its energy-giving benefits, an example of how it is stored can be used: given one-gram of glycogen - the body's primary fuel source - is stored with three grams of water, if it were to be stored in place of fat, which contains nine calories per gram in comparison to carbohydrates four grams, as fuel, a typical 155-pound male would have to weigh an additional 120 pounds.
As well as providing energy and promoting the release of important hormones, fat cells also have an ability to cushion and insulate the body, while fat ensures the absorption of vitamins A, D, E and K. Controlled levels of fat in the diet will help to the maintain levels necessary to effectively provide a thermal layer that will protect the body against cold conditions.
Fat in this capacity serves as a temperature control mechanism to insulate. It is also important to overall wellbeing in its role as a protector of vital organs. Regardless of how low we reduce our body fat, we all should maintain at least three percent, a percentage that will help to cushion vital organs, in particular the kidneys, heart and intestines.
This will help to hold these organs in place and protect them from injury. To illustrate the importance of this protective mechanism, the body will actually draw from these body fat stores last when its energy reserves are being tapped into.
Fat is also needed to absorb certain vitamins that are crucial for health and wellbeing. A, D, E, and K, the fat-soluble vitamins, are so named as they are absorbed by, and stored in the fat cells to be used when needed. In fact this is one of the main benefits to having adequate fat in our diets. The recommended daily intake for fat is low (10-15 grams) so most people will achieve the desired amount through their diet.
Who Is Likely To Become Obese & Why?
Generally speaking and as discussed, body fat per se is not the problem; instead, its volume and distribution is what often leads to its reputation as a health concern. While some are genetically more susceptible to storing higher amounts of body fat, others seem to stay slim regardless of how many calories they shovel in.
The former group often have to fight hard to lose appreciable levels, the latter have no problem with regards to fat related conditions - rather they may actually need to increase its intake to obtain necessary levels. Those with unfavourable genetics usually gain fat more readily because one or both or their parents are overweight.
In some cases, this obesity problem stems from a survival mechanism needed to sustain certain populations in their original cultural context. For example, the peoples of various Pacific Islands, due, in part, to the cold temperatures experienced travelling by canoe from island to island, developed, as an evolutionary survival mechanism, an additional fatty layer.
Obesity generally did not pose a problem for them. Today, descendants of these people do not brave the same conditions but still have the genetic predilection for fat storage. This inclination combined with modern technology, which often reduces energy output, while increasing overeating due to the abundance of foods available, often results in obesity in people with unfavourable genetics.
If only these people, on a wider scale, knew of this genetic limitation, they could change their eating habits and counter their inbuilt propensity for fat gain. Indeed, changing dietary habits is often touted as a key to controlling weight gain for any population. Compared to some island cultures and their genetic fat storage potential, however, other populations may become obese through different means.
The impact imparted behaviours can have on future weight gain cannot be understated. Often obese parents will feed their children the kinds of food they themselves ate growing up. Thus, these children, already having the genetics for rapid fat gain, will build more fat cells from an early age, which will contribute to obesity in later life (world reports suggest childhood obesity is on the rise globally).
Fat Cell Growth:
The reason some people gain body fat, whereas others do not is not always genetic in origin though. Like muscle cells, fat cells can also be increased, especially at a young age. Eating fatty foods will, over time, encourage the development of new fat cells. These cells will attract the aforementioned free fatty acids, which will swell them to a greater size, ultimately manifesting itself in obesity.
Although fat can always be lost from these cells, the cells themselves will always be there ready to grow larger with further excessive dietary fat intake.
Women and men also experience body fat distribution in different ways. Women, who are genetically programmed to carry more weight for maternal reasons (hence their higher recommended percentage range), tend to accumulate it around their hips and buttocks, whereas men, who are typically leaner and more muscular, generally store it around the waist (the average man has 26 billion fat cells whereas the average women has 35 million).
While both sexes can become obese with excessive calorie consumption, women will, in general, find it harder to lose stubborn body fat. One basis for this, in addition to maternal reasons - maternal fat is essential for reproduction and maintained on the female body to prepare for pregnancy - is its necessary role in ovulation and the higher levels of testosterone men have: it is known that girls don't begin to menstruate until their bodies are composed of at least 17 percent body fat, and men, with their higher testosterone levels will burn greater levels of body fat, both during exercise and at rest due to this hormones ability to use fat for fuel.
So although, as we have seen, there are genetic, cultural, and social reasons for body fat storage, most of us will become obese, or on a lesser scale overweight, if we live our lives in such as way to promote fat storage.
How Does Body Fat Reduction Work?
Body fat reduction can be approached in several ways. One of the keys ways to ensure life-long low body fat levels is to prevent fat cells from growing excessively in the first instance. For most, this means maintaining a diet low in the wrong types of fat (saturated and trans fats) right from the outset. However in all practicality most of us will achieve a good supply of fat cells by adulthood, making the reduction of excessive fat storage all the more important.
The keys to reducing body fat are quite simple but the science behind them is complex. Two major ways to counter fat storage are aerobic training, which uses oxygen and fat as a main fuel source, and resistance training, which builds the necessary muscle needed to stimulate the metabolic rate to burn fat to faster degree.
During aerobic activity, where the body works continuously for an extended period at a lower intensity level, the body will effective liberate fat stores (technically free fatty acids) for energy. Given our bodies carry a comparative abundance of fat, as the most efficient energy source available, it will continue to draw from these stores provided one does not cross the anaerobic threshold. At this point carbohydrates will become the preferred source and direct fat burning will cease.
With resistance training the nature of the activity is anaerobic in nature, therefore it will not directly use fat as fuel. Rather it will opt for carbohydrate in the form of stored muscle glycogen. However, as an indirect fat burning tool, resistance training is unparalleled.
Given muscle is a metabolically active tissue - meaning it takes much energy to keep it functioning - it needs a significant amount of fuel in the form of fat to maintain it. Thus, the more muscle one has the greater their fat burning furnace will be and the more body fat they will lose.
Body fat is something that we all have to a greater or lesser extent and it's value as a health component is undeniable. However, excessive amounts have been shown to be problematic, fuelling the desire of many to rid their bodies of it.
From a bodybuilding point of view fat is the enemy as it obscures hard-won muscle, from a health standpoint it can cause a raft of problems including heart disease, diabetes and obesity. Conversely, and as this article has shown, fat serves a valid purpose, as part of the intricate design that comprises our physiology, to keep us functioning properly.
Understanding this vital nutrient and how it works to keep us healthy could be seen as a major step forward in health maintenance and disease prevention.
- UCLA Healthcare. (2004). Fat cells play active role in overall wellness. [Online]