Preventing Overweight and Obesity in Scotland: A Route Map Towards Healthy Weight

APPENDIX 1: THE SIZE OF THE PROBLEM

Defining obesity

Obesity is the disease process of excess body fat accumulation, with multiple organ-specific pathological consequences ( ICD-9 code 281). ³⁵ Definitions of obesity and overweight used in epidemiology are based on the relationship between height and weight, Body Mass Index ( BMI) calculated by dividing an individual's weight in kilograms by their height in metres squared, or on measures of central fatness including waist circumference. In adults, overweight is defined as a BMI between 25-29 kg/m ² and obesity is defined as a BMI greater than or equal to 30 kg/m ². As children have different growth patterns at different stages of childhood, obesity in children is defined as having a BMI within the top 5% of the 1990 UK reference range for their age and sex and overweight as BMI within the top 15% of the range.

Prevalence of obesity and overweight in Scotland

The Scottish Health Survey provides information on the prevalence of disease and risk factors and lifestyle behaviours for a representative sample of the Scottish population. One of the risk factors measured is BMI.

Prevalence of overweight and obesity measured by Body Mass Index ( BMI) in Scotland: men and women aged 16+ ('all adults')

Prevalence of overweight and obesity measured by Body Mass Index ( BMI) in Scotland: children aged 2-15

Note - Due to changes in the methodology for calculating children's BMI, figures for 1998 and 2003 were revised on publication of the 2008 report. Full details of the change in methodology are provided in the Scottish Health Survey 2008 report (chapter 7). http://www.scotland.gov.uk/Publications/2009/09/28102003/0

Causes of obesity

The UK Government's Foresight report (2007) referred to a " complex web of societal and biological factors that have, in recent decades, exposed our inherent human vulnerability to weight gain". The report included an obesity system map with energy balance at its centre, covering more than 100 variables that directly or indirectly influence energy balance. These variables can be grouped into seven predominant themes:

• Biology: an individuals starting point survival advantage of an appetite which exceeds immediate need the influence of genetics and ill health on fat accumulation
• Activity environment: the influence of the environment on an individual's activity behaviour
• Physical Activity: the type, frequency and intensity of activities an individual carries out
• Societal influences: the impact of society
• Individual psychology: for example a person's individual psychological drive for particular foods and consumption patterns, or physical activity patterns or preferences
• Food environment: the influence of the food environment on an individual's food choices
• Food consumption: the quality including energy-density, quantity (portion sizes) and frequency

Small daily increases in energy intake can explain weight increase at a population level over time, assuming that physical activity levels have remained low. It should, however, be recognised that at an individual level, large variations in energy intakes and eating behaviours exist. For most people these variations are quite modest.

Consequences of obesity

Overweight and obesity pose a serious threat to long-term health. During childhood obesity can be associated with asthma, type 2 diabetes, musculoskeletal problems and psychosocial impacts relating to stigma and bullying. There is evidence of a high rate of unhealthy weight continuing into adulthood, but whether or not overweight and obese adults were overweight as children, they face multiple accelerated pathologies resulting in an increased risk of:

• Hypertension (high blood pressure)
• Osteoarthritis
• Dyslipidaemia (low HDL cholesterol and high triglycerides)
• Type 2 diabetes and its complications
• Coronary heart disease
• Stroke
• Gallbladder disease
• Sleep apnoea and respiratory problems
• Indigestion
• Venous thrombosis
• Asthma
• Cancers of the colon, rectum, prostate, endometrium, breast and ovary
• Low back pain
• Pregnancy and childbirth complications (including increased risk of caesarean section, postpartum haemorrhage and maternal death)
• Psychological ill-health

For any individual when there are major changes in physical activity, the number of calories/day required increases with body weight. Obese people must consume more calories to avoid weight loss. To maintain each 10kg weight gained, as fat, demands an extra 150-250kcal every day.

Obesity is associated with a significant increased risk of dying prematurely. The largest ever published study, ³⁷ analysing data from around 900,000 people in Western Europe and North America, showed that BMI of 30-35 leads to a reduction in median survival of 2-4 years and BMI of 40-45 (morbid obesity) leads to a reduction of 8-10 years. This is comparable to the effects of smoking, and it has been suggested that it may mean that normal weight parents may have to face their morbidly obese children dying before them.

Severe obesity (eg BMI>50) is increasing most rapidly, and although still relatively uncommon presents enormous costs through disability and social care, transport and attendance allowances, special housing demands and greatly increased costs of hospitalisation.