Food is considered as the necessary nutrient for human body and an enjoyment for the human mind. Since the beginning of civilization, human has developed sophisticated foods for consumption for the above two purposes. Human senses of sight (colorful presentation), smell (aroma), taste (stimulating taste buds and appetite), touch (texture appealing to touch and chewing) and sound (crunchiness and food preparation methods) have been all employed to judge the goodness of food. However, as we enter into the twenty first century, it appears that our food concerns have also entered a new era. Naturally, we Americans are no longer in the primitive hunt and feed days nor subject to the famine and feast cycles of an agricultural society. As a matter of fact, Americans are known to be too fat. Americans are eating too much fat food, too much sugar, too much salt, too much soft drinks, too much beef.....almost too much in everything. There is now an outcry from health professionals that we must change our eating habits and alter our diets before it is too late (mortality rate). The good news is that this message is getting louder recently. It is raising more people's awareness of what they eat and raising some food company's concern of what they produce. The bad news is that the message is loud but not clear hence producing some serious confusion about our 'food concerns'. (Food safety is also a concern, which has been discussed in an earlier article, will not be included here) There are too many formulas for weight control, exercises, diets, supplements and drugs. The society in general is regarding slim being good and fat being bad and ugly (fashion model image), but society does not seem have to have a solution to the growth of our obese population. Some people are obsessed by staying thin, being afraid to eat or to become fat. Hence some are desperately trying to lose weight and experimenting with special diets, exercises and even drugs. Some people are battling with will power to control food intake resorting to spiritual methods, fasting, meditation and religious diets. Yet others believe that obesity is hereditary or God given, hence they are not going to do anything about it. Yes, many people have a great concern to be labeled having obesity problem but they are not sure whether they have a heredity or a medical or mental problem.
Fortunately, 'food concerns' have a long history. Many empirical diets have evolved over many centuries giving hints about their effects on people's health and longevity. Recently, scientific advances do shed some lights on our 'food concerns'. Unfortunately, 'food concerns' are complex and encompassing many broad and deep knowledge domains. Every individual, depending on his or her biological background, cultural upbringing, social environment and religious belief, sometimes has very different concerns. Therefore, we don't have a clear theory or solution to deal with our 'food concerns'. However, one common understanding or perhaps a common objective is shared by almost everyone. That is we human should be able to enjoy food and stay healthy and pretty. In this article, we attempt to think about our 'food concerns'. We will try to sort out the complex issues and present some scientific facts so that we can make better sense about what are our food concerns and what we should do about them. In this article, we shall limit our discussion of 'food concerns' under four categories, namely, Fat, Obsession, Obesity and Diet. (FOOD Concerns) With scientific advancements in health and nutrition in general and genetic research in particular, we do have more knowledge about these concerns such as fat growth, causes of obsession, obesity and merits of certain diets.
Since 'FOOD Concerns' are complex issues, we elect to take a 'peeling the onion' approach to discuss these concerns. First we take a broad overview of the issues, sort of gathering all the Q&A statements in one place. Then we get into deeper discussions about these statements backed with some analysis and scientific findings. The overview is presented in a list form to cover many points. They are listed under three groups: 1. what people think about food and health (mental factor), 2. how human body deals with food and health (physical factor) and 3. which external matters have any effect on food and health (environmental factor):
The above are statements derived from general knowledge in the literature concerning food and health. Some statements are well accepted by the public and some may get different interpretations from different people. In the following, we will get into a deeper knowledge level following the four threads we defined for the 'FOOD Concerns'.
Fats in appropriate amount are an important part of a healthy balanced diet. Fats in body act as a means of insulation when it is stored under the skin as stored energy. Fats contain twice as much potential energy as carbon. Fats can be broken down into 5 different categories:
Fat intake (mostly triglycerides) is absorbed in the intestines by the following process:
The fatty acids are absorbed from the blood into fat cells, muscle cells and liver cells. In these cells; under stimulation by insulin, fatty acids are made into fat molecules and stored as fat droplets. It is interesting to note that fat cells can take up glucose and amino acids, which have been absorbed into the bloodstream after a meal, and convert those into fat molecules. However, the conversion of carbohydrates or protein into fat is 10 times less efficient than simply storing fat in a fat cell. Fat cells can store 100 calories in fat (about 11 grams) using only 2.5 calories of energy. On the other hand, it will take our body 23 calories of energy to convert 100 extra calories in glucose (about 25 grams) into fat and then store it. Our body tend to pick the efficient means to store fat. Hence, Isn't it wise that we take this fact into consideration when selecting a diet?
When we are not eating, our body is not absorbing food, thus there is little insulin in the blood converting food to energy. However, our body is always using energy, this energy must come from internal stores of complex carbohydrates, fats and proteins. Under these conditions, various organs in our body secrete hormones:
These hormones act on cells of the liver, muscle and fat tissue, and have the opposite effects of insulin. They breakdown fat for energy consumption. The first choice in maintaining energy is to break down carbohydrates into simple glucose molecules via the glycogenolysis process. Next, our body breaks down fats into glycerol and fatty acids by the process of lipolysis. The fatty acids can then be broken down directly to get energy, or can be used to make glucose through a multi-step process, gluconeogenesis, in which amino acids can also be used to make glucose. In the fat cell, other types of lipases work to break down fats into fatty acids and glycerol. These lipases are activated by various hormones, such as glucagon, epinephrine and growth hormone. (Note: some dietary supplements claim to be based on these processes) The resulting glycerol and fatty acids are released into the blood, and travel to the liver through the bloodstream. Once in the liver, the glycerol and fatty acids can be either further broken down or used to make glucose. Following the thread of discussions above, we can summarize that storing fat depends on insulin, conversion of carbohydrates and amino acids depends on insulin, but burning fat to get energy occurs when there is no insulin. This is essentially the basis for low-carb diet. We shall devote more discussion about diets and supplements in the later section.
Fat, in terms of nutritional terminology, can be divided into three main categories and other classifications:
Among all fatty acids, two have been identified as "essential fatty acids" for body development. These are called linoleic and (alpha) linolenic. These are essentials because the human body has to obtain them in a specific form in the diet. All infant milks have to contain them by law and they must be present in the correct proportion for the baby to develop well. Rich sources of them in the diet are vegetable oils.
Carbohydrates as quick energy source (Lactose, Maltose, Sucrose, Glycogen, Deoxyribose, Ribose and Cellulose) are categorized as:
Babies' and toddlers' bodies convert most carbohydrates into glucose, which is an important source of energy for them.
Proteins are essential for body growth. Human body requires proper amounts of proteins as they are necessary for healthy growth and body development. Proteins make up vital parts of every living cell. For babies, they must have proteins to make new cells and to maintain and repair old cells. The body depends on the right amounts of various proteins and minerals to function properly. From food intake, a person's body makes many of its own proteins, which have many different functions in the body. However, nobody, especially babies and toddlers, can make all of the proteins needed to be healthy. That's why it is important to ensure that they get the right balance of foods from their diets.
Diets also must supply the right amounts of minerals and vitamins to help ensure proper growth and maintain healthy body. Minerals are essential for the growth and development of good teeth, strong bones, and for the formation of red blood cells. Minerals cannot be made by the body and must come from the diet. Human body needs various kinds of vitamins to function. Vitamins can be grouped into two kinds, water soluble (Vitamin B, B1, Niacin, B6 and B12 and Vitamin C) and fat soluble (Vitamin A, D, E, and K) Each of these vitamins plays its' own important part in body development. The body requires the right amounts of various vitamins and minerals in various biological processes that allow us to maintain health and fight off infections.
Fats are stored largely in fat tissues (fat cells) under the skin, some in the liver and small amount in the muscles. Fat cells are formed in the developing fetus during the third trimester of pregnancy, and later at the onset of puberty, when the sex hormones "kick in." It is during puberty that the differences in fat distribution between men and women begin to take form. (Note: depletion of brown fat occurs, see below) In fact, fat cells do not multiply after puberty -- as the body stores more fat, the number of fat cells remains the same. Each fat cell simply gets bigger! Hence, it is important to maintain a healthy maternity diet, since it may affect the fat cell counts in the baby.
LCP (Long-Chain Polysaturated) Fatty Acids
LCPs are long-chain polyunsaturated fatty acids that are essential for the healthy development of our brain, nervous system and vision. They are especially important for babies. Mother can transfer LCPs to their unborn baby via the placenta and through breast milk once the baby is born. So it is a good idea for pregnant women to eat foods that are naturally rich in LCPs, such as oily fish like mackerel or leafy green vegetables. LCPs are naturally present in breast milk. Feeding babies milk fortified with LCPs may lead to improved IQ scores (brain development) and better eyesight in later life as reported in a recent study.
Fat Growth Observed in Mice (References 1-10)
Stearoyl–CoA desaturase (SCD) is a central lipogenic enzyme catalyzing the synthesis of monounsaturated fatty acids, mainly oleate (C18:1) and palmitoleate (C16:1), which are components of membrane phospholipids, triglycerides, wax esters, and cholesterol esters. Several SCD isoforms (SCD1-3) exist in the mouse. Ntambi et al (ref. 10) have shown that mice with a targeted disruption of the SCD1 isoform have reduced body adiposity, increased insulin sensitivity, and are resistant to diet-induced weight gain. The protection from obesity involves increased energy expenditure and increased oxygen consumption. Compared with the wild-type mice the SCD1–/– mice have increased levels of plasma ketone bodies but reduced levels of plasma insulin and leptin. In the SCD1–/– mice, the expression of several genes of lipid oxidation are up-regulated, whereas lipid synthesis genes are down-regulated. These observations suggest that a consequence of SCD1 deficiency is an activation of lipid oxidation in addition to reduced triglyceride synthesis and storage. Apart from the dramatic alterations in triglyceride and cholesterol metabolism, the SCD1–/– mice are considerably leaner than their wild-type counterparts. These studies establish a critical role for SCD in the generation of body fat. The deletion of the SCD1 gene resulted in global changes in gene expression and altered metabolic activity that can account for the loss of body fat. These metabolic changes recommend SCD as a promising therapeutic target for the many disorders associated with the metabolic syndrome. Although these studies have not been applied to human, however, some logical deduction may be very enlightening..
We all have 'food concerns' but some are obsessed by them. The fashion world parading the thin bodies on the cat walk is defining a pretty body but not necessarily a healthy body. Some models and teenage girls are obsessed with a thin body and they would try anything to keep thin. Health professionals definitely do not recommend any dieting borderlined starvation for anyone especially for growing teenagers. Similarly, the body building gyms and fitness TV programs often boast strong muscles as attractive and sexual appeal but not necessarily a normal healthy body. Some people are obsessed with a masculine body and they resort to drugs. Again health professionals would not recommend anyone to pump his or her body up with steroids. If one is obsessed with staying thin or staying muscular; it is likely one has a psychological problem. Psychotherapy may be needed to develop right attitudes toward eating and maintaining one's body weight. Sometimes, obsession is influenced by environmental factors such as peer pressure from school or work environment. In general, exercise is a good thing for health but one can not be obsessed by it. Likewise, a lean diet is generally good but one can not be blinded by no knowledge of what the nutritional value a diet offers. .It is always smart to know how one's body functions naturally and what one's body specifically need before adopting a right eating habit, a good exercise program and a moderate life style.
We discuss below how our body reacts to exercise which can help us to adopt an appropriate exercise program.
When we exercise, our bodies turn their focus on helping our muscles. Some organs such as heart works harder. Some organs such as stomach shuts down to conserve energy. Our muscles take in a source of energy and they use it to generate force. Our muscles are biochemical material, they use a chemical called adenosine triphosphate (ATP) for their energy source. During the process of "burning" ATP, our muscles need three things:
The source of energy in every cell of our body is ATP. ATP is an adenine nucleotide bound to three phosphates. A lot of energy is stored in the bonds between the phosphate groups. When a cell needs energy, it breaks this bond to form adenosine diphosphate (ADP) and a free phosphate molecule. In some instances, the second phosphate group can also be broken to form adenosine monophosphate (AMP). When the cell has excess energy, it stores this energy by forming ATP from ADP and phosphate. Chemically, ATP comes from three different biochemical systems in the muscle, in this order:
Knowing how muscle works and how the exercise team cooperates, wouldn't it make sense for us to select an appropriate exercise routine best suited for our body and life style?
Obesity occurs when the body is storing too much fat in its adipose tissue. Obesity
is defined as a heavy accumulation of fat in the body's fat cells to such a
serious degree that it rapidly increases the risk of obesity-associated diseases
and mortality. The adipose tissue is primarily located under the skin and on top of each
kidney. Men tend to carry body fat in their chest, abdomen and buttocks (Heard
of Mars Apple?). A woman tends to carry body fat in her breasts, hips, waist and buttocks
(Heard of Venus Pear? Of course not, these words are coined here for the first
time). Some obesity cases are caused by psychological problems, (depression can
cause it) Some due
to heredity (missing gene) and some due to physical illness (lack of hormone). In any case, Obesity is a
disease. The effects of this disease, in terms of death, disability and
morbidity are devastating. Despite the enormous toll taken by obesity, however,
the disease does not receive adequate attention it deserves from the parents,
the government, the health care profession or even the insurance industry. Many other
diseases, type 2 diabetes, heart disease, arthritis, stroke and other health
conditions caused by obesity are escalating every year.
Body Mass Index (BMI)
BMI is the number of your weight in Kilogram divided by your height in meters squared. For instance, if you are 1.7 meter and weighs 90 kilograms your BMI is 90/(1.7x1.7) = 31.14. According to one online source, people of average weight should have a BMI between 18.5 and 25 (kg/m2), and people with a BMI of 25 to 30 (kg/m2) are considered overweight, while people with a BMI of over 30 (kg/m2) are considered obese. (Note: the author is happy to have a BMI of 20.5)
Being overweight and obese may cause several psychological problems like feeling of inferiority, often caused by discrimination. Furthermore, many physical problems are related to obesity, like difficulties in breathing, personal hygiene, pain in the knees and back and skin problems. People suffering from obesity more frequently have high blood pressure and diseases related to hardening of the arteries, with blood clots in the heart and the brain. Other related problems include non-insulin dependent diabetes, gallstones, some types of cancer, difficulties in mobility and increased risk of mortality.
Of course, severe obesity also creates a financial burden because the amount of food and medication are consumed.
Cause of Obesity
Obesity can be hereditary, hence some people are at increased risk. However, obesity only develops from overeating, irregular meals and lack of daily physical activity. Many people think that if obesity is a disease of heredity, it is inevitable for some people to suffer from obesity. Some bring up the point that if one has inherited some bad genes which, for instance, do not regulate the fat growth, one must be obese. But this is not true because it is really the life style that determines how the genes develop in the first place albeit over a long long time. The fact that the existence of obesity has increased by five times or more since the Second World War and it has occurred mostly in US and Western Europe, is hardly due to a change of our genes but our life styles. That said, however, there is a rare possibility that some obesity cases may be due to a missing gene which does not produce the fat regulating leptin as noted in the mice experiment. Since leptin level increased in mice by injection show reduction of food intake and increase of energy expenditure resulting in weight loss, it is possible a treatment method for such gene-caused obesity can be developed in the near future. Besides these special cases, food, physical activity and mental attitude are probably the real cause for most obesity cases.
Weight loss (ref. 11-15) is always a recommended treatment for obesity. Medical treatment should be recommended only for those who could not reduce weight by diet changes, exercise or lifestyle changes or who had other risk elements and complications. Weight loss is most effectively achieved with a diet administered by a dietician but the greater challenge is to achieve a way of life that can maintain the weight and reduces the chances of putting it back on. Since obesity is a disease that you cannot expect to be cured of or be under clinical control within a few weeks or months, any promise of short-term treatment whether with exercise, diet, supplement or medicine is of suspect. Medical treatment must be expected to be long-term, possibly lifetime, in order to maintain the weight-loss and to prevent illness. However, there is no long history nor experience in medical treatment of obese patients for more than a few years. (Note: some places still think happy Buddha figure represents prosperity and happy life) The information concerning efficiency and safety of the medicines used for obesity in combination with other medicines is very limited. Until we obtain more knowledge (clinical evidences), medical treatment should be reserved for patients with high risk of complications or with complications where maintaining weight is absolutely necessary.
Medicines used for obesity generally fall in the following categories:
There is no doubt that our diet plays a critical role in maintaining our body weight with or without exercise. In the weight loss war, there are numerous diets proposed by researchers, nutrition professionals and experienced weigh-loss 'experts'. We do get confused and overwhelmed, sometimes influenced by hypes. It is advisable to spend sometime doing research and comparing diets before adopting one. The following is a list of commonly known weight-loss diets::
Blood Type Diet
Cabbage Soup Diet
Calorie restriction diet
Low Carbohydrate Diet (list) Low-carbohydrate diet(review)
Low Cholesterol Diet
Low Fat Diet
High Fiber Diet
Mayo Clinic Diet
South Beach diet
Sugar Busters Diet
Suzanne Sommers Diet
The author does not have personal experience with all the diets in the list above nor can make any comment on them. The readers are cautioned to do their own research and study before selecting any diet plan. It is highly advisable to consult your physician before committing to any diet.
Like diets, there are many dietary supplements proposed for health and weight loss purposes. Since many supplements including HCA to be discussed below all carry commercial and promotional information and claims. We shall not list them here to avoid being viewed as endorsing them. The HCA is used just as an example to caution the reader that one must do investigation on the claims and statements made about any supplement, never blindly accepting everything that is printed. Readers must make a thorough research before selecting any dietary supplement. (What it is, any theoretical basis? what are the claims? and are there any clinical proof?, etc) Here is an example:
Hydroxycitric acid (HCA), is the active ingredient extracted from the rind of a little pumpkin-like fruit, Garcinia cambogia, from India and Southeast Asia. Dietary supplements and a wide variety of weight loss formulas, contain Garcinia extract to inhibit fat production and suppress appetite. A number of products include extracts (about 50% HCA) under the brand names Citrin (Sabinsa) and CitriMax (InterHealth) and a new one called Regulator is a 98% pure potassium HCA from a small Irish supplement company.
The theory behind the HCA supplement is that HCA can inhibit an enzyme in cells, citrate lyase, which is needed for the conversion of carbohydrates into fat. In the cell, carbohydrates are broken down into citrate compounds, which are then converted (by citrate lyase) into another compound; acetyl coenzyme A (acetyl CoA) – the metabolic building block for fat synthesis. By blocking the conversion of citrate into acetyl-CoA, HCA can suppress fat synthesis. Acetyl CoA is further converted into malonyl CoA, a compound which may block the actions of carnitine acyltransferase in shuttling fatty acids into the mitochondria to be burned. When you’ve blocked the fat production, you have to do something with those excess carbs. They can’t be stored as glycogen because those stores in liver and muscle are already full, so it is thought that the body disposes of them by increasing carbohydrate oxidation (burning them). As a result of these fully loaded glycogen stores, some researchers have suggested that a "side effect" of HCA supplementation may be a suppression of appetite – which would reduce food intake and promote weight loss.
Animal studies have shown that hydroxycitrate decreases weight gain – primarily by suppressing appetite and reducing food intake. At least one rat study has also shown a loss of body weight and reduced fat mass due to an 11% increase in daily energy expenditure. HCA appears to be effective in both lean and obese rats, where it can reduce food intake, body weight, body fat accumulation, fat cell size, and serum triglycerides. Studies of HCA supplementation in humans have been equivocal. For weight loss, regular intake of Garcinia cambogia and HCA is supported by animal studies (and high carbohydrate diets), where it reduces food intake and body fat accumulation. Other studies do not support a role for Garcinia cambogia in facilitating weight loss beyond the effects observed with a low calorie high fiber diet. Since there are no serious adverse side effects associated with intake of Garcinia cambogia or hydroxycitric acid supplements aside form some minor gastrointestinal distress induced by high doses, HCA may be most effective as an aid to preventing weight re-gain – rather than as an approach to stimulating significant fat loss (which is best achieved by lifestyle modifications in diet, behavior and exercise patterns). Since it is difficult to maintain a reduced body weight following weight loss, those individuals who have succeeded in losing body weight and fat mass may be better able to adhere to their new diet and maintain their new lower body weight more effectively with the help of HCA dietary supplements.
Thermogenesis is the term used by scientists to describe the activity of BAT (Brown Adipose Tissue, brown fat tissues are more prevalent in children and get depleted when grow older), which includes dozens of biochemical and metabolic events. The basic outcome of these events is the generation of thermo units, in other words, the creation of heat in your body. Under normal every-day circumstances, people have little capacity for thermogenesis. Living in warm climates, heated homes and cars, and modern eating behaviors and stresses have all seriously suppressed human's thermogenic capacity. However, scientists have discovered how to reverse the process that strips us of our thermogenic capacity as we leave childhood, or to give us the thermogenesis that we might never have possessed (due to hereditary factors).
Thermogenesis occurs when mammals are keeping body warmer than ambient, hibernating, adapting to freezing cold or eating food. When human is eating, most thermic calories burned are directly supplied by food and not by white fat cells. Some supplements claim that they can activate the brown adipose tissue which can burn body's excess calories and white fat cells. The brown adipose tissues are located around blood vessels and organs. If they get triggered into activity, it warms the blood and through circulation the warmth is spread to the entire body. These findings do seem to promise some effective medicine for burning fat. We should stay tuned about any further studies or any effective supplements developed.
'FOOD Concerns' in terms of food intake, obsession about body appearance, obesity affecting other diseases and mortality and diets for maintaining a healthy life are really all focused on one main issue. That is to achieve weight loss and maintain a healthy BMI. Most people spoke weight loss as a war, an extremely challenging war to win. It is very difficult to lose weight and it is even more difficult to prevent gaining it all back. The connection of food and body weight are influenced by many factors, as tabulated under mental, physical and environmental factors. There are numerous solutions proposed to deal with this problem. Some are based on psychological approaches such as meditation, group therapy and religious diets. Others are based on physical approaches such as exercises, diets and supplements to control appetite and to increase fat burning. And still others are based on medical approaches attempting to temper with body's basic biochemical processes. Since the human mind and human body are both very complex subject matter and the weigh control effect can not be observed in a short time period, one must be extremely patient and careful in selecting what method or solution to win the weight loss war. As pointed out above, there are some encouraging scientific findings pointing to the possibility of a safe and effective medical treatment of obesity. Through genetic research, we have also gained much more knowledge about how human body is programmed to function. These knowledge can help nutritionists and dieticians to put some theoretical foundation for the existing diets proposed and perhaps to invent some more scientifically based new diets. Socially, we human race are now aware of the obesity problem with our current generation, and its severity for our future generation if we do not face the problem seriously. The objective of this article is to treat obesity as a serious long-term social medical concern. The broad observations and general discussions of this writing is peeling only the first few layers of the 'FOOD Concerns'. It is hoped that more people will continue to peel more layers and to get deeper into the issues so that we will be able to eliminate these concerns in a reasonable time.
Written by Ifay Chang on July 4th, 2004
Dr. Chang is the co-founder of Medical World Search which offers an intelligent medical search engine, called MWSearch. MWSearch is an independent search service without affiliation with any healthcare organization or pharmaceutical companies. Medical World Search ( www.mwsearch.com ) has been offered for public use since 1996.
In early 90's, while working as a research scientist at IBM T. J. Watson Research Center, Dr. Chang led a group of researchers developing an advanced clinic information system with the purpose of supporting efficient and reliable healthcare practice. The system with friendly user interface, extensive data and knowledge bases and multimedia document management system has been adopted by Kaiser Permanente and other healthcare organizations.
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