Obesity and its management.

Obesity is a natural response to an unnatural environment, an environment where high calorie foods are available ad libum and where  there is little need to expend  many calories in day-to-day living.  Obesity is now recognised as a major public health problem.  If government health targets for heart disease, diabetes and cancer are to be achieved obesity will need to be tackled aggressively.  Its management is complex and must be behaviour based and multi-sectorial.  Pharmacists can have a role to play but, along with other healthcare professionals, must avoid the temptation to medicalise what is essentially an environmental and lifestyle public health problem.

Facts and  figures

Obesity is the accumulation of excess fat (adipose tissue) in the body caused by eating more calories than is necessary to provide the required energy for each day’s activity 
Obesity is a major risk factor for many diseases especially type 2 diabetes and coronary heart disease.   The development and prevalence of obesity is complex  involving; psychology,  hormones,  lifestyle and environmental  as well as genetic issues.   Since a genetic basis for obesity is far from clear in the simplest of terms obesity results from too many calorie over a prolonged period of tim e.

In the UK the number of obese people in the population is increasing.  Currently some 17% of men and 19% of women are classed as obese with approximately 50% of the population between age 40 and 70 years being either overweight or obese (see table 1).   It is predicted that by 2010, 23% of women and 22% of men will be obese.  This compares unfavourably to1983 when the prevalence of obesity was 6% in men and 8% in women.  Levels of obesity in children are also increasing.   Across the UK there are differences in the prevalence of obesity. The average weight of men and women is higher in Northern Ireland than England and Scotland.  Other countries in Europe have a much lower prevalence of obesity compared to the UK, for example, in Finland just one in ten women is obese compared with one in five in England.  Currently, in Europe, Malta has the highest levels of obesity in children with over 50% of  10 year olds with a BMI of greater than 25..
             
Lifestyle has changed significantly in the past 100 years.  In  1890 the percentage of calories in the diet as fat was 15%.   In 1990 this figure was 42%.  In   the UK one quarter of both men and women live sedentary lifestyles. The sedentary levels increase with age and are highest (37%) in the unskilled socio-economic groups and lowest (17%) in professional groups.   The incidence of obesity,  and as a consequence its impact on health, is more significant in lower socio-economic groups  and reflects a common theme that  if you are less well off you are more likely  to be unhealthy. 

Studies have demonstrated differences in obesity between social classes with 21% of women in Class IV being obese compared to only 12% of women in Class I

The cost of obesity

In addition to its impact on health, obesity also has financial consequences for the National Health Service (NHS) and the UK economy with an estimated cost of at least £500 million a year in treatment costs to the NHS, and possibly in excess of £200 million to the wider economy.   These healthcare costs are predicted to escalate over the next few years as the number of obese people in the population increases. The economic and human cost of obesity is estimated to be very high with 1.8 million sick days a year and  30,000 deaths a year resulting in 40,000 lost years of working life.

Obesity and disease

Obesity is an independent risk factor for major diseases including; coronary heart disease, type 2 diabetes mellitus and cancers (mainly breast cancer and cancer of the colon, kidney and oesophagus).   It also contributes to the increased prevalence of other conditions including; arthritis, gallstones, infertility and  gynaecological problems.  In addition to its direct medical consequence it also has a significant social impact particularly in leading to depression and to some degree social exclusion.

Table 1.  BMI,  obesity and health risk

What is obesity?

Obesity is assessed (crudely) by measuring Body Mass Index (BMI).    BMI is a ratio of height (meters squared) divided by weight (kilogrammes).      BMI as a measure of obesity is arbitrary (see table 1) and can therefore only be a crude predictor of disease risk in an individual.    BMI does not discriminate between muscle mass and adipose tissue.  For example, someone who starts to exercise will achieve a reduction in adipose tissue but an increase in muscle mass. This will result in a reduction in disease risk but may not be accompanied by a change in BMI.   Other  measures of obesity such as the bioelectrical impedance test and immersion tests are more accurate and precise in predicting risk but not practical in the pharmacy setting.   For this reason BMI is widely use and a useful indicator of risk in someone who undertakes little exercise.

Where obesity exists on the body is linked to disease risk.  For example, central obesity, common in males, indicates  a greater risk of CHD and type 2 diabetes.  This is know as the “apple” shape and contrasts with  the”pear” shape more common in females where the obesity occurs on the hips and increases the risk of osteoarthritic disease. 
 
An increase in fat deposition around the abdomen – the apple shape -is the main risk factor, rather than obesity itself, for the development of type 2 diabetes.   Adipose tissue in the abdominal cavity has a high lipolytic rate which releases free fatty acids that drain directly into the liver via the portal circulation.    Flooding of the liver in this manner has a direct impact on hepatic glucose homeostasis; insulin mediated inhibition of glycogenolysis is reduced and peripheral muscle uptake of glucose is impaired. Insulin resistance develops and impaired glucose tolerance results in hyperinsulinaemia and profound dyslipidaemias.    With impaired clearance there is raised plasma triglycerides, reduced high-density lipoprotein (HDL) cholesterol, which are cardio-protective, and high levels of low density lipoprotein (LDL) cholesterol, which generate the small, atherogenic LDL particles that contribute directly to coronary heart disease.

Obesity can also result in respiratory disorders, particularly obstructive sleep apnoea syndrome. Excess fat deposited in the neck, chest wall and abdomen has adverse effects on lung function. Apnoeic episodes can lead to pulmonary hypertension, myocardial stress, excessive daytime drowsiness and altered tissue oxygenation during the night.

Therefore BMI, in conjunction with a waist to hip ration, provides a good  measure of  disease risk.    The hip:waist ratio for a female should be less than  0.9 and for males should  be less than  0.8.   There is an increased risk where a female’s waist is greater than 88 cm and a male’s waist is greater than  102 cm.

Management of obesity

Relatively modest weigh loss leads to a significant health benefit.   Ten percent weight loss is typically associated with around a 30% reduction in abdominal obesity.    This gives significant improvement in; blood pressure, dyslipidaemia and insulin resistance and a consequence reduction in morbidity and mortality.

Impact of lifestyle changes

Two studies provide the evidence that avoiding obesity, through a healthy diet and increasing exercise, reduces the risk of developing type 2 diabetes.    . 

Study 1, conduced in Finland, considered  middle-aged, overweight people with impaired glucose tolerance.   The lifestyle intervention involved counselling aimed at; reducing weight, total intake of fat (especially saturated fat), increased fibre intake and increased physical activity.

The net weight loss after 2 years was not great (3.5 kg in the intervention group compared to  0.8 kg in the control) the incident in diabetes was 11% in the intervention group compared to  23% in the  control group and the result significantly different.

Study 2, conducted in American, demonstrated that intensive life-style intervention in a group of patients at risk of developing type 2 diabetes resulted in the number developing the disease being halved compared to a control group.   The lifestyle changes involved a low-fat diet and 30 minutes of moderate exercise (mostly walking)  each day.

These studies provides our best evidence of the direct impact of controlling obesity and indicates that lifestyle adjustment should be central to any initiatives.

Supporting motivation to change.

Successful management of obesity requires a multi-factorial, multi-agency approach.  If weight loss is to be successful, and sustained over a long period, patients must be at a point where they are prepared to commit to a sustained lifestyle change.    This requires discussion of motivation and setting realistic goals.   Regular encouragement and reinforcement of lifestyle changes are important.  Diet and exercise are the mainstay of any weight loss strategy.  Pharmacological aids and “special diets” can only be an adjunct to this approach.    Adoption of a healthy balanced diet with a reduced calorie content in association with increased exercise remains the best, and most sustainable, way to maintain long-term weight loss.   

Exercise for life

The level of exercise taken is directly linked to the benefit of reduced disease risk.     In addition the level of activity suggested in the government guidelines will bring health benefits but may only maintain body weight rather than reduce it.   A recent paper published  has suggested that the government exercise targets would need to be doubled to effect weight loss in an individual that  continues to eat the same calories.  This  was picked up widely by the lay press and  such information only serves to confuse the public in what is good for their health.   This paper was not stating that exercise brought no benefit and pharmacists  have  a role in  objective reporting of  such information.

Government targets

Everyone should be encouraged to take either;

a. Six 30 minute periods of gentle exercise per week such as brisk walking

OR

In practical terms this can be difficult for many especially those over weight and over 50 years of age.   Obese people can find exercise difficult and care must be taken to ensure that they do not injure themselves when becoming involved in strenuous exercise.

Often it is best, when discussing exercise with overweight and obese people,  to use the word “activity” since exercise has a connotation of formalised activity that many may feel they are unable to comply with.  Listening to clients and finding out their personal barriers to taking exercise is a useful way to start supporting them towards change. For example they might not be happy walking in their neighbourhood at night – walking with a few friends might be the way to resolve this.

Despite the widely known public health burden and years of individually based intervention approach, physical inactivity remains a growing problem among industrialized nations.   Interventions aimed at increasing physical activity usually result in small changes in behaviour that are forgotten about within weeks.

Regular physical activity is an important part of effective weight control.   Increased energy expenditure helps to increase lean muscle mass, decrease total body fat and improve overall fat distribution. Physical activity improves mood and sense of well-being.     Exercise also plays a part in preventing several diseases and improving overall health. For example, physical inactivity results in almost a two-fold increase in coronary heart disease.     Physical inactivity is also associated with increased risks of developing colon cancer, non-insulin dependent diabetes mellitus and high blood pressure.

A Better Diet

Diets should contain food from all four food groups: bread and cereals, fruit and vegetables; meat and fish; diary products.  Above all individuals must enjoy their diet otherwise concordance will be poor.

The diet should provide sufficient nutrients and maintain health. For those who are overweight or obese, low-fat and reduced sugar foods will accelerate weight loss. People should be  encouraged to eat five portions of fruit and vegetables per day, these can be raw, cooked, canned, frozen or dried and one portion may be substituted with a glass of fruit juice if preferred.

Once some weight loss has been achieved regular encouragement and reinforcement of lifestyle changes are important. This may be done by attending weight-loss groups or by regular assessment on a one-to-one basis, for example, on subsequent visits to the pharmacy.

The principle of good dietary management:

Pharmacotherapy

The National Institute of Clinical Excellence (NICE) supports the use of Orlistat (Xenical ®) and Sibutramine (Reductil ®) in specific circumstances and has issued guildelines for their use in primary care.   Rimonabant (Acomplia®) has been recently launched and its role in managing obesity is still to be properly evaluated.
           
Orlistat is a lipase inhibitor that acts locally in the gut to reduce the absorption of dietary fat. The drug covalently binds to the lipase enzymes, resulting in 30% of dietary fat passing through the gastro-intestinal tract unabsorbed.   NICE advises that it can be used in patients aged between 18-75 years with a BMI of at least 30 or with a BMI of 28 in the presence of associated risk factors, such as type-2 diabetes, hypertension or hyperlipidaemia.    Orlistat can only be prescribed to a patient who has achieved a weight loss of at least 2.5kg over a period of four consecutive weeks before the start of treatment through diet and exercise alone.

Sibutramine inhibits the uptake of both serotonin and nor-adrenaline, thus it has two modes of action. Firstly, sibutramine acts centrally leading to a feeling of fullness (satiety), resulting in a reduction in food intake. Secondly, sympathetically mediated thermogenesis maintains ‘original’ basal metabolic rate (BMR) even when weight loss occurs. Normally, BMR will decrease as weight is lost, thus conserving energy and making it hard to lose more weight.

Patients prescribed sibutramine must have their blood pressure monitored. Both blood pressure and pulse rate should be checked every two weeks for the first three months, every four weeks for the second three months, and then at least every three months after that. If an increase in heart rate of 10 beats per minute (bpm) or a rise in blood pressure of at least 10mmHg (systolic or diastolic) is found at two consecutive checks, therapy should be stopped.

NICE advises that sibutramine can be given to patients aged between 18-65 years with a BMI of at least 30 or with a BMI over 27 in the presence of at least one associated risk factor. It can only be prescribed to people unable to display and maintain a weight loss of at least 5% through lifestyle changes within three months.

Rimonabant Acomplia is an oral selective cannabinoid receptor antagonist.  It is thought to affect the endocannabinoid system in the brain that modules the intake of palatable, sweet or fatty foods.   It is licensed as an adjunct to diet and exercise for the treatment of obese patients (BMI >30 ) or overweight patients (BMI >27) with associated risk factors such as type 2 diabetes.

Although drugs cannot replace exercise and dieting and should not be used alone, drug therapy is appropriate as long as it is done in accordance with current recommendations and with co-ordinated support for the patient.  

Popular Slimming Diets and Over the Counter (OTC) Products

Many obese people will attempt the latest fad diet that promises quick results, as a consequence there have been a massive increase in the number of diet books being published. These popular slimming diets fall into a number of categories as follows:

Very few of these diets comply with healthy eating principles. They may lead to weight loss in the short-term, but they do not encourage the change in eating behaviour necessary for maintaining a lower weight.

 In addition to these popular slimming diets there are a wide variety of over the counter (OTC) weight control products available. The ingredients of these products are thought to act by either one or both of the following mechanisms:

Examples of some of these ingredients include L-carnitine, chitosan, chromium, fibre, hydroxycitric acid (HCA), seaweed and lecithin
.
There is little evidence to support the benefit for any ingredients contained in OTC weight control products.

By far the most popular fad diet currently is the Atkins diet.  It has the power to effect considerable weight-loss in a very short time.  Named after the American physican Dr Atkins who popularised and promoted the diet it is however based on work of William Banting in the early 1900s which led to the discovery of insulin and the management of diabetes.   By restricting carbohydrate intake insulin secretion is suppressed.   Without insulin the body attempts to metabolise fats – as in diabetes – with resultant loss of glycogen from the liver.  Glycogen is associated with water and  the resultant weight loss over one or two weeks can be as great as 3 or 4 stones.  However such a diet is unsustainable and possibly carries considerable health risks.