Adult obesity 1: tackling the causes of the obesity epidemic and assessing patients

Author

Debbie Cook, BSc, Dip Nurse Practitioner, is clinical nurse manager, Rydal Practice, Woodford Green, Essex, and is a board member of the National Obesity Forum.

Introduction

If current trends continue, 60% of men, 50% of women and 25% of children in Britain will be obese by 2050 (Foresight, 2007). Foresight’s report highlights the weakness of current anti-obesity measures and the scant evidence for any truly effective treatment or prevention policies. It acknowledges that excess weight is increasingly seen to be the norm in society and, due to lack of awareness of sustainable or even available healthy, cheap lifestyle choices, individuals can no longer be held solely responsible for obesity.

The UK appears to have a particular problem, with obesity levels rising threefold between 1980 and 2001. Levels of extreme obesity nearly doubled among women in the 1990s and trebled in men. By 2007, 56% of women and 65% of men were overweight or obese (NHS Information Centre for Health and Social Care, 2008).

Clearly this overwhelming problem deserves attention. However, responsibility for the action plans needed to tackle this immense social burden can no longer be shouldered by primary care alone. Policymakers are beginning to realise that social engineering and corporate responsibility encompass the need for a change in attitudes to public health – it is everyone’s responsibility to work towards an environment which is less obesogenic (Kennedy, 2008).

Causes of obesity

So why is our environment so obesogenic? The existence of a genetic predisposition towards obesity caused much media excitement in 2007 when teams at Oxford and the Peninsula Medical School in Devon established the existence of the FTO gene, which appears to affect weight regulation. Certain diseases such as Prader-Willi and Bardet-Biedl syndrome are also causes of marked obesity (Chee and Olczak, 2008; Kennedy, 2008), although they are rare.

Much more commonly, people living in a modern social environment seem particularly susceptible to obesity (Qi and Cho, 2008). In Kennedy (2008), two leading researchers debated the causes of obesity: genes or environment? One argued that obese people will be found in every society and this is more the result of the over-availability of tasty, nutritionally dense food and lack of physical exercise. The opposing researcher disagreed, arguing that the most important influence on individuals’ degree of adiposity is their inherited set of genetic variants (Kennedy, 2008).

The widespread lifestyle habits of developed societies, together with a genetic predisposition which favours thrifty people who can survive in times of famine, is one of many accepted reasons for the continuing trend towards a heavier society. Yet times are changing and we are seeing the end of the era of cheap food. Lock (2009) predicts that food price inflation will further compound the obesity problem as people buy relatively cheaper, poorer quality foodstuffs to save money. Energy expenditure is also changing, with television and other media frequently blamed for rising levels of obesity.

Visceral fat

The health threat from obesity is now known to stem largely from fat around the organs, or excess visceral fat (Fig 1). This in turn leads to abdominal obesity, hypertension, glucose intolerance and insulin resistance, resulting in increased cardiovascular risk.

Until recently adipose tissue was thought to be inert, having little effect on the body, but new research shows it is a secretory endocrine organ producing chemicals which are toxic to the body. Free fatty acids are carried by the hepatic portal circulation, which in turn raises hepatic glucose output and thereby hepatic insulin resistance. The rise in free fatty acid formation causes hypertriglicidaemia, more insulin resistance and reduced glucose use by muscles. Excess visceral fat promotes insulin resistance, dyslipidaemia and the release of adipokines. The net result of these changes is an increase in insulin resistance and inflammation which is pro-atherogenic (Karet, 2008; Eckel et al, 2005).

Impact of obesity on other long term conditions

Obesity is implicated in a number of diseases. It is directly associated with the morbidity and mortality from diabetes, cardiovascular disease, cancers, sleep apnoea syndrome and chronic obstructive pulmonary disease (COPD). Largely this is attributable to the insulin resistance and other metabolic abnormalities caused by excess visceral fat and dyslipidaemia, as explained above (Qi and Cho, 2008).

Metabolic syndrome, a clustering of abnormal physical findings, was classified by the International Diabetes Federation (2006) as the core presence of central obesity with any other two of: hypertension; raised triglycerides; raised fasting blood sugar levels; and low high-density lipoprotein (HDL) cholesterol levels. People with metabolic syndrome have a five-fold greater risk of developing type 2 diabetes, if not already present (Stern et al, 2004).

Obesity and co-morbidities

However, many experts now feel the metabolic syndrome does not go far enough to explain and identify cardiovascular risk factors. We now need to move on from this tool and begin to consider the perception that other factors such as polycystic ovarian syndrome and non-alcoholic fatty liver disease are also implicated (Haslam, 2008; Preiss and Sattar, 2007).

Obesity also increases the risk of cancer - approximately 70,000 new cancers a year are diagnosed in Europe which are attributable to excess body weight, with obesity-related cancer a greater problem for men than women (Dobson, 2009). A recent survey of around 4,000 people found only 3% were aware that body weight was a risk factor for cancer (Cancer Research UK, 2009).

Departures from the normal physiological and metabolic state carefully maintained by the body’s homeostatic mechanisms, fuelled by weight gain, result in changes to the way that glucose and fatty acids are used by the body (Zammit, 2009).

Type 2 diabetes and insulin resistance develop as the beta cells in the pancreas become less sensitive to the effects of insulin and the resulting rise in endogenous insulin levels results in even more weight gain. Latest figures from Diabetes UK (2009) show there are now more than 2.6 million people with diabetes in the UK and more than 5.2 million registered as obese.

The benefits of living a healthy and active lifestyle should be promoted to everyone, but it is imperative for overweight and obese people to acknowledge and act on this as early as possible. Obesity is currently often classified according to body mass index (BMI) but in many people it is more helpful to measure waist circumference as this gives a greater indicator of risk, especially in those of Asian origin. Table 1 explains the BMI classification of weight (Poirier et al, 2006).

Measuring obesity

As with any long term condition obesity management requires a practical, focused approach. Even modest weight loss can produce health benefits and reduce risk.

Nurses in primary care are likely to have the most contact with obese or overweight people, often as a result of them attending for some other (seemingly unrelated) condition. Convincing apparently otherwise asymptomatic patients of the importance of risk factor interventions, for example reducing waist circumference, is often fraught with difficulty (Turner, 2007). However, there are significant variations in the management of those with obesity, co-morbidities from the condition or metabolic syndrome (Barnett et al, 2009).

Patients may present to nurses in primary care as a self-referral, as a GP referral or, increasingly, as a referral from acute care with instructions that they must lose weight before they can undergo operations/procedures.

Assessment is the key; all patients should have a comprehensive assessment at the outset of their treatment plan with agreed goals and outcomes based on this (Box 1).

Broaching the subject

Perception of obesity is a major issue. If patients feel fit and healthy, they do not seek out practical help and advice from healthcare professionals. It is often only when they start to have symptoms that they feel the need to consult professionals for help.

Embarrassment will stop many from accessing care, as well as fear that practitioners will blame them for putting on weight. Indeed, the lay definition of “risk” and “obesity” are often far removed from healthcare professionals’ own criteria, which presents a barrier to communication (Johnson-Taylor et al, 2008).

Healthcare professionals can also slip into a blame culture that is not conducive to weight loss. Fry (2004) also argued that practitioners are capable of ignoring the obvious signs of a nutritional disorder such as obesity, only offering interventions when medical complications have (inevitably) become apparent.

Brief interventions with open questions about which aspect of patients’ health bothers them the most (such as fear of diabetes) will often elicit a response that can be used as an opening to a discussion about weight or lifestyle. Using current statistics as evidence, an obese woman is 12 times more likely to develop diabetes (Stern et al, 2004).

Finding a diplomatic way to approach people about their weight which does not alienate them is not easy. Pearson (2004) suggested the best way is to ask patients what they feel they can do to become more healthy, examine how food fits in to their day and encourage an exploration of health beliefs to confirm that their ideas about weight loss are correct.

Conclusion

There are clear benefits in treating obesity and its health sequelae, the co-morbidities of cardiovascular disease, diabetes, cancer and others. Consistent, whole system-approaches are needed to reduce the effects of this currently poorly managed condition.

• Part 2 of this unit, to be published in next week’s issue, explores treatment and management options for overweight and obesity.