B1-06: The changing social patterning of obesity: an analysis to inform practice and policy development

Principal investigator

Background

The prevalence of overweight and obesity continues to increase. A socioeconomic gradient in the prevalence of excess body weight has emerged, such that it has increasingly become a condition associated with lower socioeconomic position. For example, in the 1958 birth cohort no socioeconomic gradient in overweight or obesity was observed in childhood or young adulthood, but a gradient has emerged in mid-life . Recent cross-sectional studies suggest that socioeconomic gradients have become established in childhood. The emergence of these gradients may be linked, since parental fatness predicts childhood fatness.

The emerging socioeconomic gradient of obesity in children is of particular concern both because overweight and obese children have increased risk of obesity in adult life and weight management interventions among children and young adults are of limited effectiveness . Evidence from a longstanding national dietary survey indicates that in the post-war years absolute energy intakes have gradually decreased. This suggests that declining levels of energy expenditure from habitual physical activity are likely to have played an important role in the emerging obesity epidemic. However, less is known about the social patterning of diet and physical activity, and their relative importance as correlates of overweight and obesity among different population groups. Halting the rise in childhood obesity is a PSA target, and both childhood and adult obesity are a major focus of the 2004 White Paper and its delivery plan.

Aims, methods and contribution

The project used a range of datasets to investigate age, sex and socioeconomic trends in:

Overweight and obesity, using national cross-sectional and longitudinal data
Weight gain among parents and its influence on weight gain in children, using national cohort studies
Indicators of the changing epidemiology of diet and PA, using national cross-sectional and longitudinal data

The 1958 and 2000 (Millennium) birth cohort studies allowed us to explore the emergence of obesity, physical activity and diet from birth, through the childhood years, to adulthood. The 1958 birth cohort also includes approximately 4,000 offspring, thus allowing study of intergenerational effects in the generation and transmission of obesity within families. In addition to these cohorts the Health Survey for England (HSE) provides data on body mass index (BMI), diet and physical activity in children, young people and adults at different time points over the last 10-15 years.

Concurrent analyses of the datasets were undertaken, to provide an assessment of the emerging epidemic of obesity in the UK over recent decades and to detail the changing social and demographic patterning of excess body weight. In particular, we determined the extent to which inequalities in obesity are widening and the extent to which there are parallel trends in putative influences, notably diet and physical activity. Analysis focused particularly on:

how socioeconomic trends in obesity and related influences are changing over time;
how socioeconomic inequalities in BMI develop with increasing age.

These analyses of socioeconomic trends in obesity, diet and physical activity were designed to inform strategies to tackle widening social inequalities in obesity. Evidence on the likely contribution of diet and physical activity to the emerging social patterning of obesity is also important for targeting interventions at appropriate time points and population groups. Additionally, the project established baseline information on socioeconomic trends against which future trends and the effectiveness of policies in reducing socioeconomic differentials in body mass can be monitored.

Duration: January 2006 - December 2006 (12 months)