Attempts to treat established obesity in adulthood may be too late to have important impacts on disease prevention or health improvements as there is evidence that obesity in children and adolescents has already resulted in long-lasting metabolic and vascular abnormalities, write Dr Debbie Lawlor (Bristol University) and Dr Nish Chaturvedi (Imperial College, London) .
They argue that targeting the prevention of obesity during key periods of a child's development could be the way to reduce subsequent risks of adult obesity and associated chronic disease.
The perinatal period and puberty/adolescence could be two critical periods during which interventions might have long-term effects.
There is increasing evidence that intrauterine over-nutrition predicts life-long obesity. High maternal glucose, free fatty acid and amino acid plasma concentrations result in over-nutrition of the foetus which, through permanent changes in appetite control, neuroendocrine functioning or energy metabolism in the developing foetus, leads to obesity in later life. Strict glycaemic control during pregnancy could held to prevent this.
Adolescence may also offer a unique opportunity to modify the risk of future obesity, perhaps via short-term interventions as behaviours such as dietary patterns and levels of physical activity are largely formed in adolescence and persist into adulthood.
Dr Lawlor said: "New behavioural, environmental and pharmacological approaches for the prevention and treatment of obesity in children are needed. However, the epidemic of childhood obesity is unlikely to be resolved without concerted political action."
Debbie A Lawlor and Nish Chaturved: Commentary: Treatment and prevention of obesity – are there critical periods for intervention? Int J Epidemiol., doi: 10.1093/ije/dyi309
2. Smoking during pregnancy increases risk of overweight offspring
Maternal smoking during pregnancy increases the risk of overweight in children before the age of eight years, according to a new study by Dr Aimin Chen and colleagues at the US National Institutes of Health.
Using data for 34,866 children enrolled in the US Collaborative Perinatal Project, the researchers examined maternal pregnancy smoking in relation to weight, height and body mass index (BMI) in offspring at ages one, three, four, seven and eight years.
Although children of mothers who smoked during pregnancy were found to weigh less at birth, their weight quickly equalled or exceeded that of other children. In the period up to eight years old, the children of smokers were more likely to be overweight, particularly the girls. Maternal smoking in the third trimester of pregnancy was more strongly associated with child overweight than maternal smoking in the first trimester.
Dr Chen said: "Lower birth weight among infants of prenatal smokers results in greater post-natal catch-up growth which is associated with increased risk of diabetes, hypertension, and cardiovascular diseases.
"In addition, maternal smoking during pregnancy may be associated with poor appetite control in offspring. Just as adults who stop smoking can experience weight gain, babies who experience withdrawal from in utero smoking exposure after birth may also be susceptible to increased weight gain."
Aimin Chen, Michael L Pennell, Mark A Klebanoff, Walter J Rogan and Matthew P Longnecker: Maternal smoking during pregnancy in relation to child overweight: follow-up to age 8 years Int J Epidemiol., doi: 10.1093/ije/dyi218
3. Tackling obesity in the developing world
Obesity will continue to spread in the developing world where governments and health services have few effective public health levers with which to arrest the trend, writes Andrew Prentice of the London School of Hygiene and Tropical Medicine.
Profound alterations in the structure and composition of diets across the globe, coupled with very rapidly changing patterns in physical activity have resulted in a macro-environment that is highly conducive to obesity.
The recent World Health Organisation (WHO) report on Diet, Nutrition and the Prevention of Chronic Diseases placed obesity at the top of the public health agenda. Its argument for action is based partly on the economic consequences of inaction, for example heart disease, stroke and diabetes could cost China $4556 billion in the period 2005-15.
Dr Prentice said: "Major new initiatives by governments worldwide are needed to combat the external factors that contribute to the obesity pandemic such as the low cost of highly refined oils and carbohydrates, the encouragement towards motorized transport and the growth of sedentary forms of employment. These aspects of globalisation are infiltrating traditional lifestyles even in the poorest of developing countries.
"However, the prospects of halting the obesity pandemic within the foreseeable future appear remote as most countries will not be able to afford any measures to tackle the problem beyond public education campaigns warning of the health consequences of very high levels of body fat."
Andrew M Prentice: The emerging epidemic of obesity in developing countries Int J Epidemiol., doi: 10.1093/ije/dyi272
Notes to Editors
This issue of the IJE was overseen by associate editors, Dr Debbie Lawlor (Bristol University) and Dr Nish Chaturvedi (Imperial College, London).
For copies of the papers, please contact barbara.coatesworth@bristol.ac.uk
Contact details for Dr Debbie Lawlor: 0117 928 7267, d.a.lawlor@bristol.ac.uk
The International Journal of Epidemiology is a key journal in the field of epidemiology and public health, published six times per year by Oxford University Press. It is edited at the Department of Social Medicine, University of Bristol, which is a leading centre for epidemiology, health services research and public health in the UK and was one of only three to be awarded the top 5* grade in the 2001 Research Assessment Exercise.
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