OBESITY

by Dr John Cohen MA, MSc, MB BS, FRCGP, FRGS, Director of the Centre for Community Care and Primary Health, University of Westminster; Senior Lecturer in Primary Health Care, Royal Free and University College Medical School; General Practitioner, London

Obesity is the most common nutritional disorder in the developed world and is associated with several serious health risks. In earlier times and other societies, being fat was an advantage in times of famine and was often associated with higher social classes, in particular, barons, lords and monks.(1)

Concerns about obesity are recorded in Greek literature. In Shakespeare's King Henry V, the king says of obese Sir Jack Falstaff: '... doth thou not know that the grave doth gape for thee three times more than for other men'. Early in the 20th century, insurance companies began to notice that obesity was often associated with early mortality, especially in relation to hypertension and heart disease.

In 1976, a Department of Health and Medical Research Council working part concluded: 'we are unanimous in our belief that obesity is a hazard to health and a detriment to well-being. It is common enough to constitute one of the most important medical and public health problems of our time, whether we judge importance by a shorter expectation of life, increased morbidity, or cost to the community in terms of money and anxiety'.(2)

But very little seems to have happened since that time, although several experts have continued to point out the risks of obesity. In 1992, Kent and Bowyer said that 'obesity is one of the most important preventable causes of ill health in the UK'.(3)

The prevalence of obesity is increasing in both developed and developing countries, and is strongly associated with increases in dietary intake and reduced levels of physical activity. Obesity is becoming a considerable problem among children in affluent, urbanised, industrial societies such as those of Western Europe and the USA.(4)

Measurement of obesity

The best measure of obesity is the body mass index (BMI), calculated from the weight in kilograms divided by the height in metres squared. Women are considered to be overweight at a slightly lower BMI than men. An alternative measure is waist size - the risks of obesity increase as the waist measurement increases above 94 cm in men and 80 cm in women.

The scale of the problem

The number of obese people in the UK has increased considerably over the past decade. More than half of all men and just under half of all women are overweight (BMI greater than 25), whereas women are found in greater numbers among the obese (BMI 28-40) and very obese (BMI greater than 40).(5)

In 1992 in The health of the nation,(6) the last Conservative government set targets to reduce the proportion of adult men and women with a BMI of over 30 to around 6% and 8% respectively by 2005, but these are unlikely to be achieved. The health of the nation: one year on,(7) published in 1993, reported an increase in obese men from 8% in 1986 to 13% in 1991, and the proportion of obese women increased from 12% to 15% in the same time. The proportion of overweight men (BMI 25-30) increased from 34% to 40% from 1980 to 1990, while that of women increased from 24% to 29%.

Obesity in women is six times more common in social classes 4 and 5 than in classes 1 and 2, and it rises with increasing age.(8)

Internationally, the overall incidence of excess weight and obesity is highest in Canada, followed by The Netherlands, Norway, Australia, the USA and the UK.(9)

Risks of obesity

Overweight or obese people are at risk of developing several conditions (Box 1), and the higher the BMI the greater is the risk.

In an Australian study(10) it was estimated that 10% of deaths in 1989 were caused by obesity-related disease, although obesity rarely appeared on the death certificate. Other conditions such as osteoarthritis are merely disabling and do not cause an increased mortality, but they affect the quality of life for the patient quite explicitly.

The Whitehall study(11) of 18,403 British civil servants aged 40-64 years, over a 7-year period, showed that obesity in men with a normal glucose tolerance increased mortality by 10%, but if the glucose tolerance was impaired, the increased mortality risk was more than 40%. The conclusion was that a man aged 45 years with a BMI above 30 has about three times the mortality risk of a man with a BMI of 20-25.

Causes of obesity

When the body's intake of energy exceeds the output over a period of time, the individual will gradually become overweight and eventually obese. Many factors affect food intake and energy expenditure. Some of these are internal and based on body composition and the resting metabolic rate. Others factors are external and depend on messages and cues received by the eyes, nose and mouth. The amount of energy expended by an individual depends on his or her occupation, lifestyle and personal habits.

Genetic factors

Several studies have examined whether genetic factors play a significant role in the development of obesity. Although studies reviewed by Floch and McClearn(12) showed that two out of three obese patients had obese parents the shared environmental factors, such as eating habits, were more likely to be significant. However, a study of adopted children showed that there was greater correlation between the weights of the children and their natural parents, than between children and their adoptive parents.(13)

Socioeconomic factors

Socioeconomic factors seem to be important in some people. In 1992, Garrow claimed that 'in addition to metabolic considerations there are social factors that predispose to substantial weight gain, such as low educational level, chronic disease, little physical activity, high alcohol consumption, loss of employment and child-bearing in women'.(14)

Women from higher social groups may be better educated and know more about food and nutrition, and more familiar with the benefits of exercise and have access to exercise facilities. They may be more conscious of their appearance in the competition for education, work and personal relationships.

Psychological factors

Psychological factors are also important, as overeating may occur as a consolation in times of acute or sometimes chronic

trouble. Loneliness, anxiety and depression may all lead to abnormal eating habits. An obese person may be more influenced by habit, time and the taste of food than by feelings of hunger, but there are no specific aspects of personality that separate obese from non-obese people.(15)

Management of obesity

The management of overweight and obese patients entails reduction of their body weight and maintenance of the reduced weight. The risks of being overweight and obese are long term, so the weight-control programme has to be continued for life.

Obesity in children

Many children eat too much and do little exercise. Reducing sedentary behaviour in children can improve their weight.(16) Good behaviour and habits start in youth, and parents, GPs, practice nurses and health visitors should all be aware that they can prevent excess weight and obesity in adults - in particular, by increasing the dietary intake of vegetables, fruit and fibre, reducing the intake of sugary drinks and snacks, and encouraging regular exercise.

Reduced-calorie diets

A reduced-calorie diet is the main form of management for all overweight and obese patients. After this, the options depend on the severity of the condition and patient motivation. A high-fibre, low-fat diet is recommended to reduce the risk of heart disease, stroke and some cancers (Box 2). A daily intake of 1000-1500 kcal should lead to a weight loss of 0.5-1.0 kg a week. Compliance is not easy and depends on the individual's motivation and satisfaction with the diet, the diet's palatability and whether it provides adequate nutrition.

Patients should be told that weight loss may be more rapid in the first 2 weeks of the diet, as a result of water and glycogen depletion, and they should not give up if weight loss is not so rapid after this. Encouragement and practical or psychological rewards - for individuals, families or groups - assist compliance.

Exercise

Regular aerobic exercise is a valuable adjunct to the management programme as it helps to achieve the necessary balance between food intake and energy expenditure. This can be achieved by the individual alone, or as part of a group activity, and many GPs are now encouraging more exercise for patients, and in some cases purchasing exercise programmes in local facilities.(17)

Follow-up

Follow-up and review by the patient's GP, practice nurse or dietician at the surgery will provide support and psychological reward for a change in lifestyle, which can be very difficult for many people. If there is limited or no weight loss, then the many factors in the patient's life, family and work situation that prevent change should be explored and the completion of a detailed food diary recommended. These diaries can provide extremely valuable insights into an individual's eating habits, and they encourage patients to become active participants in the therapeutic process.

Psychological therapies

Of various forms of psychological treatment, only behavioural therapy has been shown to be effective, individually and in groups.(18)

Group activities

Group activities seem to have a higher success rate in producing and maintaining weight loss, especially when there is strong group cohesion and motivation to attend. Groups such as Weight Watchers are effective, perhaps because there are financial incentives, and have stood the test of time. Other non-profit-making groups can be equally successful.

The GP, practice nurse or practice-based dietician can start a group by inviting all patients with a BMI greater than 30 (obtained from the practice computer, or from a record of all obese patients) to attend at a certain time and place. Experience suggests that 6-7pm is a good time for many people. The groups need motivation and enthusiasm to get started, continue and succeed. Some patients will not respond to the invitation to attend, and others will stop coming after one or two attendances.

It may be preferable to have separate groups for men and women, as some factors causing obesity vary in each sex. The sessions can begin by weighing participants on arrival, followed by discussion on a variety of health-related matters (Box 3). The emphasis is on achieving and maintaining good health, not solely on managing obesity. Additional gentle exercise could be incorporated. Other sessions could address issues such as why it is difficult to change habits, looking after yourself, shopping and cooking, clothing and make-up.

For some attenders there may be little short-term weight change, but the benefits in the medium term include improved self-image and motivation. This can lead to the ability to change lifestyle at a later stage.

The support, lifting of depression and the lightening of mood induced by the group activity can also be passed on to other family members, neighbours and friends. One patient put it more succinctly: 'You have turned a group of depressed fat ladies into a much happier group - even if we haven't lost very much weight - and we can't thank you enough for that'.(19)

Very-low calorie diets

Very-low-calorie diets, which provide less than 800 kcal each day, have a place in the management of patients with a BMI greater than 30. The Cambridge diet is an example of a very-low-calorie diet, producing 405 kcal per day. The 'meals' come in a number of different forms - soups, milkshakes and desserts - each containing 135 kcal.(20)

In 1993, the National Task Force on the Prevention and Treatment of Obesity reported that very-low-calorie diets were initially more successful than conventional low-calorie diets, but the long-term outlook for those following them was no better.(21)

For overweight patients (BMI 25-30 in men and 23-28 in women), the same study recommended combining nutritional education and behaviour modification, a balanced low-calorie diet, and an exercise programme. For obese patients (BMI greater than 30), very-low-calorie diets were recommended as part of a comprehensive educational, behavioural and exercise programme.

Drugs for obesity

Patients sometimes request drugs to help with their weight-reduction programme. Over the years a large number of drugs have been tried and rejected on the grounds that they were ineffective or produced unpleasant or dangerous side-effects.(22) The British national formulary currently lists only the bulk-forming agent methylcellulose and the centrally acting drug phentermine as adjuncts to the treatment of obesity, but neither is recommended for use. Phentermine is licensed for only 12 weeks' use, and carries the risk of pulmonary hypertension.(23)

There has been recent interest in this area with the launch of orlistat, which is a gastro-intestinal lipase inhibitor. There have been three published multicentre studies of the effectiveness of the drug in a combined dietary and exercise programme.(24,25) The latest is a 2-year study in the USA, which began with 1,187 participants randomised to orlistat or placebo. By the end of 2 years there were only 403 participants remaining, 45% of those randomised and 34% of those who began the run-in period. In addition, there was a near 10% dropout rate because of adverse effects for those on orlistat compared to 4% for placebo, mainly because of steatorrhoea. While there was a small and persistent reduction in body weight in participants who completed the study, the benefits versus the economic cost of a 10% reduction in body weight using this drug means patients must be chosen with care.(26)

Surgical treatment

Surgical treatment should be considered as an additional optional treatment in patients who are very obese (BMI greater than 40), if dietary and behavioural modification have been unsuccessful, although the number of patients who agree to referral will be quite low. Gastroplasty to reduce the size of the stomach is the preferred operation but should be preceded by a very-low-calorie diet for several weeks before the operation.(27) Intestinal bypass and jaw-wiring procedures are no longer acceptable.

Outcome for obese patients

Enthusiasm and motivation, on the part of patients and the primary care team, are essential for a successful outcome. Exercise and a group approach improve the outcome with psychological, social, educational and diet-ary advice offered to active, interested par-ticipants who obtain mutual encouragement and support.(28) Other studies have suggested that restricted diets are ineffective, and not worth the effort involved.(29)

None of these management options will be of any use unless there is mutual understanding, confidence and cooperation between the patient and a key member of the primary care team, who offers support and follow-up. The patient will need encouragement and personal motivation to deal with aspects of his or her life that they might not wish to confront, and to change long-established habits on a permanent basis. I suggest that general practice is best placed to carry out this mission. Running a dietary management clinic or group may also be a way of encouraging those who find it hard to lose weight to try again, without the feeling of rejection.

Changing personal habits will be easier for some and harder for others, but the benefits of even a small weight loss are significant in physical, psychological and social terms. For example, in population terms, a small weight reduction makes animportant contribution to reducing the amount of ischaemic heart disease, hypertension and diabetes.(30)

Conclusion

It would seem logical and sensible for more effort and resources to be made available for health education and the prevention of obesity, starting by teaching children and young people about the benefits of a healthy lifestyle, including regular exercise. Care and attention could also be given to health promotion at work and through providing suitable leisure activities free, or at much reduced prices, to offset the advertising of high-calorie foods and drinks. Perhaps this is where the effort should be made.

Box 1. Risks associated with being overweight or obese.

• Ischaemic heart disease
• Cerebrovascular disease
• Noninsulin-dependent diabetes
• Cancer of uterus, cervix, ovary, breast
• Hypertension
• Hypercholesterolaemia
• Gallbladder disease
• Osteoarthritis
• Gout
• Ovulatory failure
• Menstrual irregularities
• Polycystic ovarian disease
• Complications after surgery
• Complications in labour and delivery

Box 2. Dietary advice for obese patients.

• Eat three meals a day. Meals should be low in fat and sugar and high in fibre
• Eat complex carbohydrates (bread, potatoes, rice, pasta and cereals) regularly, although not in excess
• Increase your intake of fibre. Eat wholemeal or granary bread, high-fibre breakfast cereals, brown rice, wholemeal pasta and all fruit and vegetables, including potatoes
• Reduce your fat intake. Avoid fried foods; grill or bake instead. Cut the fat from meat before cooking it. Limit the quantity of crisps, biscuits and pastry you eat. Use low-fat milk, spreads and cheeses
• Reduce your sugar intake. Avoid added sugar, confectionary, sweet biscuits and cakes. Use 'diet' or sugar-free soft drinks

Box 3. Discussion topics for a group of obese patients who are attempting to lose weight.

• Simple dietary advice
• Preparing and cooking low-calorie foods
• Making food tasty but less fattening
• Do we eat to live or live to eat?
• You are what you eat
• Keeping healthy
• Starting an exercise programme
• Clothing and make-up (for women-only groups)
• Care of the feet
• Changing habits for life
• Assertiveness and motivation training
• Psychological factors in eating
• Overcoming depression, dealing with stress

Practical points

• In Britain more than half of all men, and just under half of all women are overweight (BMI >25 for men and >23 for women). More than 8,000,000 adults are obese or very obese (BMI >30).
• Obesity in women is six times more common in social classes
• and 5 than in social classes 1 and 2, and increases with age.
• Obesity has genetic, environmental, cultural, social and psychological causes in different proportions in different people.
• The treatment of overweight and obese patients involves reducing body weight, and maintaining it at the lower level. The self-management programme that is agreed has to be continued for life.
• Patients should be warned that for the first 2 weeks of a reducing diet they may experience a more rapid weight loss than later in the programme. Encouragement and rewards assist compliance.
• Regular aerobic exercise is a beneficial adjunct to a dietary programme.
• Very-low-calorie diets (less than 800 kcal a day) have a place in the management of patients with a BMI greater than 30.
• Drugs have a limited place in the management of overweight and obese patients, and should be use for short periods only.
• Surgical treatment (gastroplasty) should be considered in patients who are very obese (BMI >40), if dietary treatment has been unsuccessful.

References

1. Ayers W. Changing attitudes towards overweight and reducing. J Am Dietetic Assoc 1958; 34: 23-4.
2. James W. Research in obesity: a report of a DHSS/MRC group. London: HMSO, 1986.
3. Kent A, Bowyer C. When weight gets out of control. Doctor May 1992; 48-9.
4. Murata M, Hibi I. Nutrition and the secular control of growth. Horm Res 1992; 33: 89-96.
5. Colhoun H, Prescot-Clarke P. Health survey for England 1994: a survey carried out for the Department of Health. London: HMSO, 1996.
6. Department of Health. Health of the nation. London: HMSO, 1992.
7. Department of Health. Health of the nation: one year on. A report on the progress of the health of the nation. London: HMSO, 1993.
8. Goldblatt P, Moore M, Stunkard A. Social factors in obesity. JAMA 1965; 152 : 1039-42.
10. Crowley S, Antioch K, Carter R et al. The cost of diet-related disease in Australia. Discussion paper, Australian Institute of Health and Welfare and National Centre for Health Program Evaluation, 1992.
11. Fuller, Shipley M, Rose G, Jarrett R, Keen H. Coronary heart disease risk and impaired glucose tolerance. The Whitehall Study. Lancet 1980; i: 1373-6.
12. Floch T, McClearn G. Genetics, body-weight and obesity. In: Stankard A, ed. Obesity. Philadelphia: W. Saunders, 1980.
13. Withers R. Problems in the genetics of human obesity. Eugenics Rev 1964; 56: 81-90.
14. Garrow J. Treatment of obesity. Lancet 1992; 340: 409-13.
15. McCrae C, Yaffe M. The obese, eating and their bodies: mind over matter? Treating overweight. No. 1, March 1986. Servier Laboratories.
16. Savage J. Children: weight and lifestyle. British Nutrition Foundation Bull 1996; 21 (Suppl.) 28-32.
17. Nichol J, Coleman P, Brazier P. Health and health care costs and benefits of exercise. PharmacoEconomics 1994; 5: 109-22.
18. Bjorell H, Rossier P. Long-term treatment of severe obesity: four year follow up of results of combined behaviour and modification programme. Br Med J 1985; 291: 379-82.
19. Cohen J. Running a dietary management clinic. Update 1992; 44: 1053-63.
20. Howard A. The Cambridge diet. London: Jonathon Cape, 1985.
21. National Task Force on the Prevention and Treatment of Obesity. Very-low-calorie diets. JAMA 1993; 270: 967-74.
22. Bowen R, Glicklet A, Kier M et al. Cardiac valvulopathology associated with exposure to fenfluramine or dexfenfluramine. US Department of Health and Human Services Interim Public Health Recommendations, November 1997. MMWR Morb Mortal Wkly Rep 1997; 46: 1061-6.
23. Appetite suppressants. British national formulary, No. 36 London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 1998, 188-9.
24. Sjostrom L, Rossanon A, Andersen T et al. Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. Lancet 1998; 352: 167-73.
25. Hollander P, Elbein K, Kirsh I et al. Role of orlistat in treatment of obese patients with type 2 diabetes. Diabetes Care 1998; 21: 1288-94.
26. Davidson M, DiGirolamo M et al. Weight control and risk factor reduction in obese subject years with orlistat: a randomised controlled trial. JAMA 1999; 28: 235-42.
27. Anderson T, Backer O, Astrup A et al. Horizontal or vertical banded gastroplasty after pre-treatment with very-low-calorie diet: a randomised trial. Int J Obesity 1987; 1 : 295-304.
28. Garrow J. Should obesity be treated? Treatment is necessary. Br Med J 1994; 309: 654-5.
29. Wooley S, Garner D. Should obesity be treated? Dietary treatments for obesity are ineffective. Br Med J 1994: 309: 655-6.
30. Goldstein A. Beneficial health effects of weight loss. Int J Obesity 1992; 16: 397-415.