Definition and distribution of obesity
medical description of obesity is simple :
It is a situation in which the body fat mass is above the standard norms which correlate age, sex, height and muscular mass.
The definition of the World Health Organisation (WHO) is even more straightforward: obesity is an excess of body fat leading to negative consequences on health (1997 report).
definition is more simple, and has the advantage of setting the records straight:
when a doctor is referring to obesity according to the correct definition,
he is not talking about a "state" or "excess weight",
but of a true morbidity.
We will be looking at how to measure obesity, and thereby define it, however, it is important to emphasise from the start that measuring obesity still does not take into account all the factors that create this morbidity.
obesity is spread across the body:
Excess body fat can be evenly spread across the body or concentrated within certain areas. A scientific classification of obesity has actually been made on the basis of how the fat is distributed throughout the body:
Type I: "harmonious" distribution of obesity across the body.
So-called gynoid obesity, where the fat is concentrated on the lower part
of the body (hips, pelvis).
This is more typically the female type of obesity. It may be considered the least aesthetical, but it is also associated with the lowest medical risks.
Type III: So-called visceral obesity: where the fat is on the internal organs, such as the abdominal visceres. This obesity is therefore less obvious to the eye, but it is the type which is associated with the highest health risks in the long-term.
Type IV: So-called android, concentrated on the trunk of the body. This typically characterises male obesity and is generally dangerous.
The technical and aesthetic implications of the different types of obesity will be further reviewed in the section on plastic surgery.
Regulation of the appetite
The human brain is equipped with centres that simultaneously regulate the sensation of hunger and of satiety. These centres are found in a small gland situated within the centre of the brain called the hypothalamus. These centres are sensitive to blood hormones called neurotransmitters, which exert a stimulating or inhibitating effect on hunger and satiety.
The neuro-mediators are adrenaline, noradrenaline, dopamine, and serotonine. Certain drugs such as the anorexigenes (or "hunger inhibitors") act on the neuro-mediators. These drugs are derived from amphetamine and increase the release of dopamine and adrenaline in the area where hunger is regulated, leading to the suppression of the latter.
The flenfluramines in turn increase the release of serotonine where satiety is regulated, thus stimulating it.
->> All mediators constantly interact, leading to an extremely fine-tuned regulation of the appetite and satiety for each individual, which is closely linked to their individual calorific needs and physical activity.
Causes and mechanism of obesity.
The usual cause of obesity is an unbalance between energy intake and output. There are indeed intricate weight-regulating mechanisms that act upon the Body's energy stores. The latter can in effect be "destored" when the body needs them, thereby compensating for a lack of energy intake compared to one's needs.
The daily energy output is made up of three entities:
>> Basic metabolism: this is the minimal output necessary for the body to remain alive. It depends essentially on the lean mass (which encompasses mostly the muscles) and represents 70% of the total energy output.
>> Physical activity: this of course varies greatly, from the sedentary person to the hard labourer. It accounts on average for 20% of the total energy output. Because of the excess weight an obese person carries around, even when exerting only moderate physical activity he will be using up more energy than someone with normal weight.
It is therefore easy to understand why physical activity alone will not enable an obese person to achieve maximum weight loss. However, if the main element of a correctly balanced diet is an overall decrease in food intake, sport will play a significant role as it will assist in maximising its effects. Sport has moreover been shown to be beneficial in the long term as a means to prevent a relapse.
Thermogenesis: this phenomenon
results from the metabolism of food - absorption and storage - after meals.
It represents 10% of the total energy output. A certain amount of the calories absorbed during a meal are therefore immediately "burnt off" by digestion. This explains why jumping a meal does not fit into sensible dieting recommendations.
Taking into account the above facts, and coupling these the notion that moderate but constant overeating can lead to a state of obesity, it is easy to understand the difficulties to obtain good therapeutic results with diets. In particular, it is known that only to maintain their lean body mass - in particular with regard to the muscular component - obese people are dependent on hypercalorific food rations.
The fact that the obese patient depends on a hypocalorific diet to survive is enough to inevitably fall into bad eating habits. An internationally renowned specialist has clearly explained the problem:
of energy balance is easy to understand; it is its quantitative nature that
is often disregarded. A typical obese patient will have increased body weight
by some 20 kg over 10 years. This means a daily energy excess of 30-40 kcal
(0.126-0.168 MJ) per day at the start of the development of obesity, which
gradually has to be increased to maintain the enlarged body. A daily energy
excess of this magnitude corresponds initially to less than half a sandwich
or to the lack of low to moderate intensity exercise (eg, walking or climbing
stairs) for half an hour.
(Per Björntorp. Obesity. The Lancet, 1997).
a true inequality for weight-gain in normal subjects, which can explain a
feeling of unfairness. The famous experiences of Sims, carried on with inmates,
are very relevant: some of them had a high-calorie diet (more than 10000 calories
per day, whereas the normal intake is an average of 2200 calories). Only a
minority of them could gain some weight (more than 6 kg), precisely the ones
that had a family background of obesity, which is an acknowledged cause of
(Sims. Endocrine and Metabolic effects of Experimental Obesity in man, 1973).
that encourage obesity
The above statements clearly show how obesity in itself is a complex phenomenon. Without getting too specific, the main factors that induce obesity can be roughly divided into the following main groups.
Factors related to Food.
These intervene at three levels.
- Excess intake (quantity): obviously food intake must vary according to a person's physical activity. A sedentary person will use up much less energy than a labourer. Too much food and not enough physical activity will inevitably lead to a person putting on excess weight.
- Imbalance in intake (quality): without going into too much detail, we know that fat (lipids) plays an important part in creating an imbalance. Excess intake of so-called fast-acting sugars (sweetened drinks, chocolate, etc) is also detrimental. In effect, these sugars are stored as fat and are then difficult to get rid off.
- Eating disorders: these include the absence of regular meal times, a problem characteristic of modern industrialised countries; and an overall poor lifestyle incompatible with regular meals. In a few cases there can be an alteration of the central nervous system regulating the appetite, but this is only true for a small minority of people.
Factors related to energy output
This relates to the state of being sedentary in the large sense of the term, and also to the change from an active to a sedentary lifestyle.
There is certainly a genetic predispostition (linked to numerous genes, not just one) which makes an individual, or members of a same family more susceptible to becoming obese within a given environment. We should not, however, conclude that obesity is a genetic illness, except for very rare and specific cases such as the Prader-Willi syndrome which affects adolescents and combines obesity and mental deficiency.
As described in the chapter on the psychological aspects of obesity, there is no such thing as a typical psychological profile for an obese person. In other words, there is no specific trait of character or anatomy of the psychism that predisposes towards obesity. On the other hand, certain psychological states such as depression or stress can influence weight gain. Matters are further complicated by the fact that weight gain in turn can lead to a number of abnormal psychological traits which could wrongly be interpreted as the cause of obesity.
Social and cultural factors
It is wrong to infer that poverty predisposes towards obesity, however an inverse relationship between income and obesity can be observed in all western countries. This can be explained by different eating habits (more fat in the diet for the poorer classes of the population) and unequal rights to healthcare. Hardly one century ago obesity was considered as a sign of wealth and prosperity. Today the tendency is towards the opposite, where the rich can be seen " taking care of their body ". It is in fact the life styles that have have been adopted today which exert a bad influence on eating habits : global reduction in physical activity due to improved means of transport which lead to people walking less, a reduction of sport activities in schools, an increase in fast-food restaurants and vendors of high calorific sweet drinks and foods, the disappearance of regular eating times, snacks eaten in front of the television, and more recently videos and an increased use of computers for recreation means.
brief introduction to illustrate how relative the criteria describing obesity
have been :
In the United States, the definition of " ideal weight " which is based on height, was significantly lowered for women between 1943 and 1980, whereas it has remained virtually unchanged for men.
A debate arouse after a revision made in 1983 and women's ideal weight was reajusted to a higher level on the basis of new statistics on mortality. However, many experts saw this revision as a step back. In other words, the definition of normal or ideal body volume (body size) reflects the cultural and aesthetical standards of the time; medical discussions are also the reflection of these standards. The result is that for western societies like the United States, the current aesthetical ideal of body volume is thinner than the medical ideal.
Let us look at the figures. For a first estimate, weight is set against height. In this way we obtain the two common criteria used to measure excess weight which are :
>> Excess weight in relation to ideal weight for a given height
is defined as follows:
For the man: ideal weight = height (cm) - 100 - (height-150/4)
For the woman: ideal weight = height(cm) - 100 - (height-150/2)
For a woman with a height of 1m 60, the ideal weight is of 160-100-10/2=55 kg
For a man with a height of 1m 60, the ideal weight is of 160-100-10/4=57.5 kg
- The body mass index, where weight is divided by the height squared
weight ranges between 20 to 25 kg/m2.
- Between 25 et 30 kg/m2 , one is described as being overweight.
- Severe obesity starts at 30 kg/m2. This corresponds to the definition of obesity given by the WHO (World Health Organisation).
- Morbid obesity is defined as from 40 kg/m2, or as from 35 kg/m2 provided that there are associated comorbidities related to excess weight
thickness, which can be measured with a compass.
- Percentage of fat mass, which is measured with more sophisticated techniques such as the Bioelectric impedance; special weighing scales also exist.
- The waist-hip ratio measurement.
Frequency, cost and social consequences of obesity
In Europe : Obesity is unfortunately on the rise.
For example in France, its prevalence is of about 7%. According to the last available survey carried out by the SOFRES in 1997, 8.7% of men and 7.9% of women over 15 years of age are obese, which represents an body mass index of over 30 kg per square metre. These figures are even more worrying if one simply talks about being overweight (starting at 25 kg per square metre), in which case 36.7% of the population is affected.
>> In the United States and the rest of the world: here as well the situation tends to be worsening, as it is also in certain countries of the developing world. In the United States, over 50% of the population is currently considered overweight (over 25 kg/m2).
Below is an estimate of the prevalence of obesity in Europe and the United States in 1993, where obesity is definded as a body mass index above 30% (medical definition of obesity according to the WHO), for a population aged between 40 and 60 years.
-> North Europe 10% 15%
-> Western Europe 13% 16%
-> Southern Europe 16% 30%
-> Russia 14% 44%
-> United States (caucasian population) 15% 18%
-> United States (afro-caribbean population) 20% 37%
>> The cost of obesity. Costs can be split into two categories.
Direct costs, which are those incurred within the health system, and which are attributed to various specialties in the absence of the recognised pathology. In other words, they are all the medical costs linked to obesity.
Indirect costs are the days off work and lost income.
The direct costs were estimated to correspond to 5.5% of the total expenditure made on health in the United States, or 4% in the Netherlands, which corresponds to several billion(US) or thousand million(UK) US dollars or Euros.
A correlation also exists between BMI (body mass index) and co-morbidities (that is, all the illnesses related to obesity). A Finnish study even demonstrated that for each section of the population there existed a significant correlation between BMI and the overall additional medical costs incurred every year which included consultations with general practitioners or specialists and hospital admissions.
These findings are quite alarming for the health care system. They call for political and administrative decisions to be taken in order to incourage prevention. A lot remains to be done in this area.
Social concequences of obesity
Obesity is both a social and cultural a handicap in every day life. In effect, obese people often find themselves to be the victims of discrimination both and at school, on the sports ground and within the professional setting. Whithin certain professions (secretarial and public relation positions, etc) it is often very hard for the obese person to compete for the job despite offering equal qualifications. Obese people frequently have psychological problems which also contribute to this social rejection. The same applies to the pathological phenomenons and medical complications, which eventually lead to isolation.
Major options in the treatment of obesity
When we talk about the treatment of obesity, it is important to specify what criteria are used to evaluate the effectiveness of a given treatment. Short-term effectiveness should be discarded right out. We should only be looking at long-term effectiveness. This is where many debates between specialists arise. The methods available to treat obesity can be roughly be divided into three categories, from the simplest to the most intricate (or aggressive) treatment:
and support groups
- drug therapy
- surgical techniques.
Diets and support groups:
These are the traditional methods used to treat obesity. There is an overall scientific consensus on their effectiveness. Although they should be the first option to be offered to an obese patient, there comes a point where they are no more an option for those who have repeatedly attempted, but failed weight-loss using such methods. All diets are based on some form of understanding of weightloss, however, the well-founding of some of the diets on offer is sometimes quite dubious. Many are only effective if applied within a given environment or with specific support. The latter offer a good psychological frame but tend to be effective only as long as the patient feels under the constraint of a specific environment, as it is the case with health institutions.
It is important to distinguish between two types of medical treatment :
- The first
deals with the complications linked to obesity such as diabetes, hypercholesteromia,
- The second includes the actual anti-obesity drugs. Some have been tried and abandonned, other more recent drugs are still in the experimental stage.
These techniques include actual surgery performed on the upper gastro-intestinal tract (stomach, and sometimes the intestines), although this approach is limited to people with a BMI above 40 kg/m2. Another alternative, the intra-gastric balloon, has not yet been validated.
Treatment strategy for the obese patient
A treatment stategy can only be based on a case to case evalutation of each obese patient. More than with any other current pathology, treatment will have to be tailor-made despie a rough outline being made of the treatments that will follow.
The first step is a thorough evaluation of the patient's medical history (illnesses,
any surgery they may have undergone), treatments already tried, eating habits
+++, behaviour and psychological profiles, physical activities and hobbies,
family and professional surroundings. A strategy is then devised for each
What needs to be understood from the start is that any form of treatment of obesity needs to be undertaken with the long-term in view. Obese patients sometimes find this hard to accept as they are desperate to find a "miracle treatment". Long-term effectiveness is, however, the only guarantee of success. The treatment programme can be set up as a gradual succession of therapies, the choice of which will depend on the seriousness of the case and the results obtained from previous treatments.
>> First, the patient and the doctor must agree on weight loss objective. This must be reasonable and adapted to the patient, that is to say, it must be realistic. This is where a lot of the problems arise, between the patient who wishes to lose "all excess weight" as fast as possible, and the doctor who, based on his previous experience and on the available literature, knows that only realistic objectives can be met. It is important to realise that a loss of only 10% excess weight can significantly improve complications or morbidities linked to overweight, such as diabetes or hypertension.
>> The second form of treatment is drug therapy. There are many treatments on offer but these can be divided into two groups : those that treat complications linked to obesity and those that treat the obesity itself. The first type include the anti-diabetic and anti-cholesterol drugs. The second type are the appetite suppressors and those that modify fat absorption.
>> Gastric surgery offers the third type of treatment. Surgery is only available to those people who have failed with all other treatments and to the severely obese patients (so-called morbidly obese, with a BMI above 40 kg/m2, or 35 kg/m2 with co-morbidities linked to the obese state). The intra-gastric balloon is a more moderate alternative as it is less traumatic than surgery, but the objectives are less impressive with regard to weight loss. Plastic and reconstructive surgery should also be mentioned here, although they are explained in a section of their own.
>> Whatever the treatment envisaged, it is only worthwhile as long as the medical and nutritional follow-up is correct. No treatment, no drug (whether it be a miracle drug or not) can ever replace this aspect of the treatment, the absence of which almost inevitably leads to failure.
>> Finally, it is important to talk about preventative treatment, which should mainly be taken on board by the public authorities. Although this aspect of treatment is often overlooked, it is certainly one of the most promising grounds for future success. It will be the object of a special chapter.
Guide to Physical Activity
An increase in physical activity is an important part of your weight management program. Most weight loss occurs because of decreased caloric intake. Sustained physical activity is most helpful in the prevention of weight regain. In addition, exercise has a benefit of reducing risks of cardiovascular disease and diabetes, beyond that produced by weight reduction alone. Start exercising slowly, and gradually increase the intensity. Trying too hard at first can lead to injury.
Examples of moderate amounts of physical activity
Common Chores Sporting Activities
Washing and waxing a car for 45-60 minutes Playing volleyball for 45-60 minutes
Washing windows or floors for 45-60 minutes Playing touch football for 45 minutes
Gardening for 30-45 minutes Walking 13/4 miles in 35 minute (20min/mile)
Wheeling self in wheelchair 30-40 minutes Basketball (shooting baskets) 30 minutes
Pushing a stroller 11/2 miles in 30 minutes Bicycling 5 miles in 30 minutes
Raking leaves for 30 minutes Dancing fast (social) for 30 minutes
Walking 2 miles in 30 minutes (15min/mile) Water aerobics for 30 minutes
Shoveling snow for 15 minutes Swimming Laps for 20 minutes
Stairwalking for 15 minutes Basketball (playing game) for 15-20 minutes
Bicycling 4 miles in 15 minutes
Jumping rope for 15 minutes
Running 11/2 miles in 15 min. (10min/mile)
Your exercise can be done all at one time, or intermittently over the day. Initial activities may be walking or swimming at a slow pace. You can start out by walking 30 minutes for three days a week and can build to 45 minutes of more intense walking, at least five days a week. With this regimen, you can burn 100 to 200 calories more per day. All adults should set a long-term goal to accumulate at least 30 minutes or more of moderate-intensity physical activity on most, and preferably all, days of the week. This regimen can be adapted to other forms of physical activity, but walking is particularly attractive because of its safety and accessibility. Also, try to increase "every day" activity such as taking the stairs instead of the elevator. Reducing sedentary time is a good strategy to increase activity by undertaking frequent, less strenuous activities. With time, you may be able to engage in more strenuous activities. Competitive sports, such as tennis and volleyball, can provide an enjoyable form of exercise for many, but care must be taken to avoid injury.
For the beginner, activity level can begin at very light and would include an increase in standing activities, special chores like room painting, pushing a wheelchair, yard work, ironing, cooking, and playing a musical instrument.
The next level would be light activity such as slow walking of 24 min/mile, garage work, carpentry, house cleaning, child care, golf, sailing, and recreational table tennis.
The next level would be moderate activity such as walking 15 minute/mile, weeding and hoeing a garden, carrying a load, cycling, skiing, tennis, and dancing.
High activity would include walking 10 minute/mile or walking with load uphill, tree felling, heavy manual digging, basketball, climbing, or soccer/kick ball.
You may also want to try:
exercise to attain full range of joint motion
strength or resistance exercise
The Problem of Obesity
By Fintan Lynch
Courtesy of the ASO