NPRI case studies: Diet and physical activity
- Effectiveness of Fat Taxes and Thin Subsidies
- Impact of the living environment on health behaviours
- Shift-work and Health
- Early origins of obesity and the Gateshead Millennium Study
- The influence of incentives on children’s consumption of vegetables
Effectiveness of Fat Taxes and Thin Subsidies
(Professor Bruce Traill, University of Reading: October 2008 – October 2010)
Obesity is on the increase throughout most of the developed world. The Government’s Foresight analysis of 2007 showed that nearly 60 per cent of the UK population might be obese by 2050, a seven-fold increase in the direct healthcare costs of overweight and obesity and wider costs to society and business of £45.5 billion.
Despite these predictions, it is well recognised that obesity increases the risks of a range of chronic health problems including heart disease, type 2 diabetes and high blood pressure. However, it has also been shown that increased levels of fruit and vegetable consumption will contribute to a reduction in the incidence of some cancers.
Increased interest in public health policies designed to reduce the impacts of diet-related disease is apparent and appropriate. One such policy is a fiscal intervention designed to reduce the consumption of calorie- and fat-dense food and to encourage the consumption of fruit and vegetables.
This NPRI-funded research examines the distributional consequences and economic welfare impacts of a fiscal intervention policy. The study has found that there is a trade-off between public health and economic welfare from imposing a fat tax on society. Energy-dense/nutrient-poor foods are disproportionately consumed among low-income households, which are the foods most likely to be taxed by a "fat tax" policy.
The research shows that fiscal interventions will have adverse welfare implications for low-income households and that while a fat-tax/thin-subsidy approach may have a progressive redistribution of health it will have a regressive redistribution of wealth. Initial results suggest that a blanket fiscal policy is too blunt an instrument to achieve the intended results. Policies which specifically target people consuming bad diets may be more appropriate.
Further information is available from Professor Bruce Traill
Professor Bruce Traill
Email: w.b.traill@reading.ac.uk
Impact of the living environment on health behaviours
(Professor Rachel Davey, Staffordshire University: March 2006 – January 2008)
It is estimated that more than 50 per cent of early deaths and disability caused by cardiovascular diseases may be prevented using a combination of national efforts and individual actions aimed at reducing the major modifiable risk factors. There is emerging strong evidence that lifestyle, mainly through diet and physical activity, may be important in reducing cardiovascular disease risk and other risks to public health and that these, in turn, are influenced by the physical environment in which people live and work.
To examine this issue, a team of researchers from Staffordshire University led by Professor Rachel Davey carried out a detailed study of the relationship between environmental characteristics, health behaviours and health outcomes. Environmental factors considered included proximity of physical activity spaces and facilities, street connectivity, land use mix, population density, mass transport provision, traffic, safety, crime, proximity of food outlets and shops, weather and indices of multiple deprivation. Multi-level regression analyses were used to investigate the relationship between these objective measures of the living environment and health-related outcomes such as participation in physical activity, levels of overweight and obesity, early cardiovascular mortality and hospital treatments for heart disease and diabetes.
Findings from the research support the proposal that residential neighbourhood down to small area level may be important in determining health behaviours and health outcomes. Reported levels of physical activity were low and levels of overweight were high, suggesting that local environments were not supportive of the healthier lifestyles advocated by national public health policy. This point was amplified by the finding of a population intent on maintaining low levels of physical activity and poor diet despite the public health messages to become more active and to eat more healthily. The environmental factors most likely to support better population health behaviours were walking access (ideally within 5-10 minutes) to work, shops and local services; better public use of green space; and greater access to healthier eating options. Persistent wet weather emerged as a significant barrier to being more physically active. Facilities and environmental planners should consider these issues, as well as traffic calming and re-routing to reduce the incidence (and public perceptions) of urban road accidents.
In terms of health outcomes and costs to the health service, the research demonstrated a direct association between physical inactivity and early (< 75 years) cardiovascular mortality and hospital episodes for the treatment of cardiovascular disease and diabetes, suggesting direct health and social returns from investing in healthier living environments.
The research has had considerable impact on the local health economy. By focusing on specific aspects of the environment, greater involvement of the local population and better partnership working among community stakeholders, the city of Stoke-on-Trent has embarked on an ambitious environmental change process designed to reset the balance away from factors predisposing residents to adopt negative health behaviours and towards those that support positive health choices.
Further information is available from Professor Rachel Davey
Professor Rachel Davey
Email: R.Davey@staffs.ac.uk .
Shift-work and Health
(Professor Greg Atkinson, Liverpool John Moores University: June 2006 – August 2009)
About 15 per cent of the European workforce are employed in nocturnal shift-work in order to meet society’s needs for 24-hour services and emergency cover, maintaining continuing process industries in banking, services and call-centres, and also off-setting the economic effects of industrial plant shutdown. However, shift-work is associated with greater health effects and problems than “normal” day-work, including a reduction in quality and quantity of sleep, chronic fatigue, anxiety and depression, adverse cardiovascular effects including hypertension, gastrointestinal effects and reproductive effects in women.
To better understand the relationship between shift-work and health, this NPRI-funded project surveyed shift-workers and then explored the effects of leisure-time physical activity and eating habits during unusual hours of work.
A survey of 200 shift-workers from a range of occupations showed that levels of leisure-time physical activity were lowest in telecommunication shift-workers and midwives, and highest in fire-fighters although the last group had marked variation. Barriers to increasing physical activity focused on time-related factors. Relationships were found between leisure-time physical activity, shift-work experience and body mass index with 73 per cent of the least active shift-workers being overweight or obese.
Simulated night-shifts undertaken in the sleep laboratory discovered, for the first time, that a prior bout of exercise can improve the quality of daytime sleep, which is similar to well-documented evidence that physical activity improves nocturnal sleep. Exercise in the evening increased appetite hormones throughout a subsequent night-shift, unlike after daytime exercise. Finally, evening exercise lowered blood pressure during a subsequent simulated night-shift, offering the potential to moderate the well-documented relationship between shift-work and hypertension.
The final phase of the project trialled a lifestyle intervention designed for shift-workers in the telecommunications division of Greater Manchester Police. The intervention was based on individualised counselling via the novel motivational interviewing approach. The intervention group showed a significantly lower body mass index on follow-up than the comparator group, although other outcomes such as blood pressure and digestive health were unchanged.
The study has indicated that physical activity influences several of the health outcomes deemed to be adversely affected by shift-work. The research will inform policy and, indeed, has already informed thinking by the Greater Manchester Police regarding new shift schedules.
Further information is available from Professor Greg Atkinson
Professor Greg Atkinson
Email: G.Atkinson@ljmu.ac.uk
Early origins of obesity and the Gateshead Millennium Study
(Professor Ashley Adamson, Newcastle University: April 2006 – July 2008)
Childhood obesity is a major public health challenge for the UK and we need to know more about how and when it develops. The Gateshead Millennium Study (GMS) recruited mothers of 1,029 newborn babies in 1999-2000 to better understand infant feeding and growth. With funding from NPRI, the children were visited between 2006 and 2008 when aged 6-8 years old to determine the lifestyle factors and early characteristics of the children and their parents, and to explore how these may be involved in the development of childhood obesity. Direct measures of the body composition, physical activity and food intake of 619 GMS children and their parents were taken.
Overall, 24 per cent of the children were overweight or obese according to international classifications, as were 50 per cent of their mothers.
Multiple measures of body composition were combined to create an Adiposity Index, which was found to be highly correlated with the more simple measure of adiposity, BMI. This finding supports the use of BMI, at least in a clinical setting, as a useful measure of adiposity in children.
Only 7 per cent of the children were meeting the guideline of 60 minutes moderate to vigorous intensity physical activity each day. Parents overestimated how active their children were by up to two hours a day. Children ate on average 1.7 portions of fruit and vegetables daily compared to the 5-a-day recommendation.
More than 50 parents of GMS children also took part in focus groups or interviews about overweight or obesity in children and the potential for future preventive interventions. These revealed that parents’ ability to identify whether their child was overweight was limited. Parents neither used nor trusted current standards of childhood overweight and instead used alternative approaches which relied heavily on extreme cases as a reference point. Parents generally accepted that childhood obesity was a problem but thought that the scale of the problem was ‘overhyped’ and failed to recognise the problem either in their own children or in the local population.
Analysis is ongoing, and the work funded by NPRI is being extended through a UKCRC-funded PhD studentship which will develop and test obesity prevention interventions incorporating physical activity and diet in pre-school children.
The project has had important impacts, including significant coverage in the media, and citations in the Health Survey for England 2008: Physical activity and fitness and the National Obesity Observatory report Physical activity surveillance in England: what is measured and where are the gaps? (both published in 2009).
Further information is available from Professor Ashley Adamson
Professor Ashley Adamson
Email: A.J.Adamson@ncl.ac.uk
The influence of incentives on children’s consumption of vegetables
(Dr Lucy Cooke, UCL: September 2008 – September 2011)
The quality of children’s diets is cause for serious concern in the light of increasing awareness of the impact of diet on health in childhood and adulthood. For very young children, the feeding strategies used by parents or caregivers are an important influence on food choice. Using rewards to encourage children to eat healthy foods is common among parents but there is some evidence to suggest that this may not have the desired effect. However, research is scant and results mixed, and it is still not clear how best to use rewards to encourage positive changes in children’s diets.
This on-going three-year project, being carried out by the Health Behaviour Research Centre at UCL, is designed to compare the effects of verbal rewards (praise), tangible rewards (stickers) and no rewards (repeated tasting alone) on children's liking and intake of disliked vegetables. Four hundred and eighty south London 4-6 year olds took part in the first of two studies to test how these feeding strategies affected acceptance of a vegetable that was initially disliked.
Preliminary results indicate that children who received rewards, either as stickers or praise, significantly increased their liking and intake of their target vegetable and these changes were maintained for three months. There was also a slight increase in intake in the sticker group as compared with the praise group, and this too was maintained for the post-intervention period. Children who were exposed to their target vegetable without rewards liked their vegetable more but did not eat more of it and, as expected, children in a no-treatment control group did not like or eat more of their target vegetable after the intervention period.
An important contribution of this research will be to provide scientifically-based guidance to improve the child feeding advice given to parents and others involved in feeding young children, and to inform future healthy eating interventions.
Further information is available from Dr Lucy Cooke
Dr Lucy Cooke
Email: lucy.cooke@ucl.ac.uk