These sessions aim to increase your awareness and knowledge about obesity. Completion of the workbook and attendance at the seminar should inform you about the increasing prevalence of obesity world-wide, the underlying reasons for this increase, the health consequences of obesity and the management of obesity in different health care settings. You will also be encouraged to think about the prevention of obesity.
By the end of today's session you will have:
The number of people who are obese is rising rapidly throughout the world, making obesity one of the fastest developing public health problems. The World Health Organisation has described the problem of obesity as a "worldwide epidemic". It is estimated that around 250 million people worldwide are obese, about 7% of the adult population. The USA has a particularly high prevalence of obesity. On average, over one third of the adult population are obese, rising to more than 50% in some ethnic subgroups. Although the UK lags behind the USA, the rate of change is very similar to the USA and this offers insight into the potential scale of the problem unless adequate strategies are adopted now to both prevent and treat obesity.
In England, the prevalence of obesity has increased steadily during the last 50 years and since the 1980's the proportion of obese people has trebled. Currently, around 40% of the adult population is overweight (BMI>25kg/m2) and a further 23% of men and 24% of women are obese (BMI>30kg/m2). The prevalence of serious obesity increases with age. In 16-24 year olds the prevalence is around 10%. By age 55-64 years obesity prevalence is over 31%; a three fold increase.
Historically, obesity was associated with affluence and this is still the case across societies. Within developing countries such as India, Africa and South America obesity is a particular problem amongst the recently affluent classes, where being overweight is seen as a sign of prosperity. However, in developed countries there is an inverse relationship between obesity and social class, with a much greater proportion of obese people in the lower social classes than in professional groups. In the UK the prevalence of obesity in women increases from 15% in social class I to 31% in social class V.
Before this session, you should read the summary document at the end of these papers which provides an overview of obesity from a World Health Organisation perspective. For those of you interested in health politics, look at the difference between the draft reproduced here and the final report available from the WHO website. A major change has taken place in the description of the causes of obesity (see strength of evidence), the final document emphasising the role of physical activity rather than nutrition. This change from the draft was brought about by the lobbying of the food industry, an extremely powerful force in American and global politics. See the paper by Swinburn et al. (2004) for an unbiased account of the role of nutrition.
Jack is 48, lives in south Leeds, and is a driver for a medium size manufacturing company. He used to drive heavy goods vehicles for a haulage firm but changed jobs as he was working away from home too much. A few months ago Jack visited his GP, complaining of pain in his left big toe quickly diagnosed as mild gout. Since it had been a while since his last visit to the practice, Jack was offered an appointment with the practice nurse for a basic health check.
Jack's health check gave the following results:
| Weight: | 1.77 m (5'10") |
| Height: | 101.6 kg (16 stone) |
| Waist circumference: | 109 cm (43 inches) |
| Blood pressure: | 160/85 mmHg |
| Fasting blood glucose: | 7.4 mmol/L |
| Total cholesterol: | 6.0 mmol/L |
Jack and his GP discuss the implications of these test results and agree that he needs to lose some weight. She gives Jack details about the Exercise on Prescription scheme that the practice is part of, and asks him to make an appointment with the dietitian attached to the practice.
About 3 weeks later the GP is surprised to find herself sitting opposite Joyce, Jack's wife. She is surprised since Joyce hasn't attended the surgery for nearly 3 years and because Joyce is seeking her assistance to lose weight. After examination, the GP notes Joyce's BMI as 31.2 and her waist circumference as 84 cm (33 inches). Joyce put on a lot of weight during her pregnancy and never managed to lose it. Indeed, she has gained a few pounds every year since. Joyce's GP has recently attended a conference on the management of obesity and understands the importance of evaluating a person's readiness for weight loss before advising on treatment.
The GP is reasonably satisfied with Joyce's replies to her questions and they agree that Joyce will join the practice weight management clinic. This is run one day per week by the practice nurse and assisted by a dietitian who covers several GP centers in the area. In order to work out her energy balance, an assessment of Joyce's usual food intake and daily activity is made.
| Source | Weight (g) | Conversion factor | kcals | % of total energy | (Recommended %) |
|---|---|---|---|---|---|
| CHO | 252 | 3.75 | (53) | ||
| Protein | 105 | 4 | (15) | ||
| Fat | 120 | 9 | (30) | ||
| Alcohol | 12 | 7 | |||
| TOTAL |
| Activity | PAR |
|---|---|
| Lying at rest/sleeping | |
| Quiet sitting activities (reading, TV, etc) | |
| Active sitting activities (driving, playing piano, etc) | |
| Stationary standing activities (ironing, laboratory work, washing-up) | |
| General mixed standing/sitting (personal activities, washing, eating, dressing) | |
| Activities involving moving about (cleaning, tidying, cooking, bowling) | |
| Walking average speed, making beds | |
| Gardening, table tennis | |
| Walking quickly, dancing, swimming | |
| Jogging, football, tennis |
For women aged 30-59, BMR = 8.3W + 846 kcal/day (W = body weight in kg)
| Activity | Duration | PAR | BMR/hour | Used energy (kcal) |
|---|---|---|---|---|
| Sleeping |
7 |
|||
| Driving |
2 |
|||
| Washing, dressing, eating |
2 |
|||
| Watching TV |
5 |
|||
| Ironing |
1 |
|||
| Cooking, cleaning |
2 |
|||
| Secretarial work - sitting |
5 |
|||
| Total: |
24 |
Joyce discusses with the practice nurse ways of increasing her energy expenditure. She is limited in what she can do because of her role as the family carer, taking and collecting her daughter from school, and her part-time job. However, they decide that she could introduce an hour's physical activity each day and reduce her TV viewing time. To begin with, Joyce takes advantage of the Exercise on Prescription scheme that the practice belongs to. This allows her 2 free entries to her local leisure center per week. Joyce used to enjoy swimming and so joins a group of others on this scheme for 2 one-hour sessions per week. For 4 of the remaining days she joins her husband Jack, in taking the dog for a walk for an hour per day. Sunday is a quiet day.
Visiting the practice again 3 months later, Joyce has lost about 3 kg. While she is pleased that she has stopped gaining weight, she is disappointed she has lost so little weight. But Joyce feels fitter and is enjoying the company of a couple of women who joined the Exercise on Prescription scheme at about the same time as her. So together they decide to go swimming once a week, do an exercise class in the leisure center twice a week, and join a dance class again twice a week. On the other two days, she walks the dog. This replaces her previous exercise regime. She also further reduces her daily energy intake from 500 kcal to 700 kcal.
Jack and Joyce's GP has been reasonably satisfied by the patient numbers joining the practice weight management clinic. However, there is still much to be done to address the obesity problem in that area of Leeds. A couple of weeks ago she read an article in General Practitioner headlined 'The Cream Cake Tax'. This described calls by doctors in the UK and US to use taxes to influence the public's diet. The idea is to place an additional tax on foods high in fat or sugar, increasing their price, and discouraging their purchase. While she thinks it's an interesting proposal she has some worries about whether to support such a policy when she goes next week to a meeting on obesity with the local Director of Public Health.
| Advantages | Disadvantages | |
|---|---|---|
| Consumer |
|
|
| Manufacturer |
|
|
| Government |
|
Government unit 'urges fat tax' Published on 19 February 2004
Fairburn, C.G. & Brownell, K.D. Eating Disorders and Obesity. A Comprehensive Handbook, 2nd Edition. New York: The Guilford Press, 2002
Jacobson, M.F. & Brownell, K.D. Small taxes on soft drinks and snack foods to promote health. Am J Pub Health, 2000, 90, 854-857.
The International Journal of Obesity - Health Sciences Library or online
Marshall, T. Exploring a fiscal food policy; the case of diet and ischaemic heart disease. BMJ, 2000, 320, 301-304.
National Audit Office. Tackling Obesity in England. London: The Stationery Office, 2001
Special section on obesity. Science, 7th February 2003, 299, 781 & 845-860
Swinburn, BA et al. Diet, nutrition and the prevention of excess weight gain and obesity. Public Health Nutrition 2004, 7, 1230146
Eckel, RH; Non-surgical management of Obesity in adults
Websites:
Association for the Study of Obesity
- in particular look at ORIC (Obesity Resource Information Centre)
National Heart, Lung, and Blood Institute (US). The Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. (available here as a pdf file)
A recent article in the New England Jornal of Medicine discussing the possibility of taxing sugary drinks
Nutrient recommendations for the prevention of excess weight gain and obesity
Background: Both developed and developing countries are experiencing an obesity epidemic although with great variation between and within countries. In developing countries, obesity is more common in people of higher socioeconomic status and in those living in urban communities. In more affluent countries, it is associated with lower socioeconomic status, especially in women, and rural communities. The direct health care costs of obesity accounted for 6.8% (or $70 billion) in the US in 1995 and somewhat less, but still a staggering amount, in other industrialized countries. Indirect costs, far greater than direct costs, include workdays lost, physician visits, disability pensions and premature mortality. Intangible costs such as impaired quality of life are enormous. Because the risk of cardiovascular disease and hypertension rise continuously with increasing weight, there is much overlap between the prevention of obesity and the prevention of a variety of chronic diseases, especially type 2 diabetes. Population education strategies will need a solid base of policy and environment-based changes to be effective in eventually reversing these trends.
Trends: The increasing westernization, urbanization, and mechanization occurring in most countries around the world is associated with changes in diet towards one of high fat, high-energy foods and a sedentary lifestyle. In many developing countries undergoing economic transition, as obesity rapidly increases, it often coexists in the same population with chronic under-nutrition. Along with the increase in obesity over the last thirty years, the prevalence of diabetes has increased more than 30-fold.
Diet and disease: Mortality rates increase with increasing weight (as measured by body mass index). As BMI increases, so too does the percentage of people with one or more co-morbid conditions. Among women, over half (53%) of all deaths can be directly or indirectly related to their obesity. Eating behaviours are closely linked to overweight and obesity and include; snacking/eating frequency, binge-eating patterns, eating out, portion size and protectively, breastfeeding at birth. Nutrient factors under investigation include fat, carbohydrate type, including refined carbohydrates such as sugar, the glycaemic index of foods, and fibre. Environmental issues are clearly important, especially as many environments become increasingly 'obesogenic'.
Strength of evidence: There is convincing evidence that a high dietary fibre intake helps to protect against overweight and obesity, whereas a high intake of energy-dense foods may increase risk (Table 1). In the category of "probably decreasing risk" are supportive home and school food environments. There is a probable increased risk from the heavy promotion of energy-dense foods and fast-food outlets on TV, frequent eating of food prepared outside home, and low socioeconomic circumstance, especially in women and in developed countries.
| Evidence | Decreases risk | No relationship | Increases risk |
|---|---|---|---|
| Convincing | Regular physical activity High dietary NSP (fibre) intake |
High intake of energy-dense foods Sedentary lifestyles | |
| Probable | Home and school environments that support healthy food choices for children Promoting linear growth |
Heavy marketing of energy-dense foods and fast-food outlets Adverse social and economic conditions (in developed countries, especially for women) Sugar-sweetened soft drinks and fruit juices |
|
| Possible | Low glycaemic index foods Breastfeeding |
Protein content of the diet |
Large portion sizes High proportion of food prepared outside the home (western countries) "Rigid restraint/ periodic disinhibition" eating patterns |
| Insufficient | Increased eating frequency |
Alcohol |
BMI can be used to estimate, albeit crudely, a population-level measure of obesity and the risks associated with it. It does not, however, account for the wide variation in the nature of obesity between different individuals and populations. The classification of overweight and obesity, according to BMI, is shown in Table 2.
|
Classification |
BMI (kg/ m2) |
Risk of co-morbidities |
|
Underweight |
< 18.5 |
Low (but risk of other clinical problems increased) |
|
Normal range |
18.5 - 24.9 |
Average |
|
Overweight |
25 - 29.9 |
Increased |
|
Obese (class I) |
30.0 - 34.9 |
Moderate |
|
Obese (class II) |
35.0 - 39.9 |
Severe |
|
Morbidly obese (class III) |
> 40.0 |
Very severe |
In recent years, different ranges of BMI cut-off points for overweight and obesity have been proposed, in particular for the Asia-Pacific region.
However, sparse data exist at present to make definitive recommendations.Waist circumference:
Men
> 94 cm, Women > 80 cmMen
> 102 cm, Women > 88 cmWaist circumference is a convenient and simple measurement which is unrelated to height, correlates closely with BMI and the ratio of waist to hip circumference (WHR), and is an approximate index of intra-abdominal fat mass and total body fat. Furthermore, changes in waist circumference reflect changes in risk factors for cardiovascular disease and other forms of chronic diseases, even though the risks seem to vary in different populations.
Physical activity:
A total of one hour per day on most days of the week of moderate-intensity activity, such as walking, is needed to maintain a healthy body weight, particularly for people with sedentary occupations.
Total fat:*
Free sugars
:** The fat and free sugars targets are indicators of the energy density of the diet. Very active groups, with diets high in vegetables, legumes, fruits and whole grain cereals, may sustain a total fat intake up to 35% without the risk of unhealthy weight gain.
Additional reading and resources
WHO Global Strategy on Diet, Physical Activity and Health
Association for the Study of Obesity