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Childhood obesity is bad news for heart disease in the future

Carl Heneghan
Last edited 26th September 2012

Apart from stating the obvious, we are in big trouble. Health services costs are rising and we can’t afford it. There are no new drugs to counteract the growing increase in chronic disease which cost us a fortune. Yet, to counteract all this we are getting fatter and fatter, and presenting a future steeped with dire consequences for our children.

Results from 63 studies of 49,220 children aged 5 to 16, published in today’s BMJ by our group, starkly illustrates the effect obesity has upon increasing risk of cardiovascular disease for future generations of children. We know that being overweight in adulthood increase your risk of heart disease and stroke, we now know that for children, these very same risk factors are increased markedly at a very young age.

Obese children have a blood pressure greater by 7.5mmHg than normal weight children. This rises to 11.5 mmHg when the more accurate ambulatory blood pressure readings are used. The increase seems to be greater for girls than boys: but the reason for this additional increase is unknown. Also, other important risk factors for heart disease are raised in obese children: blood lipids (cholesterol and triglycerides) are raised; fasting insulin and insulin resistance are worse and the left ventricular mass of the heart is increased when compared to normal children.

Being overweight as a child corresponds to a Body Mass index (BMI) of 25 to 30 and obesity as a BMI of over 30. BMI is a number calculated from a child's weight and height, and is weight in kg divided by height in metres squared (kg/m2). Although BMI does not measure body fat directly, it correlates with accurate measures of body fat, such as underwater weighing, and can be used as a simple measure for screening children.

Many countries use reference points in children to classify obesity, taking into account age, sex and a reference population. Whilst this data calculates an average for the population, and classifies obesity according to the degree of variation from this mean it may mask worrying trends due to increasing average weight of children over time. In 2007, the US obesity rates have nearly quintupled among 6- to 11-year-olds since the 1970s. Worryingly, in the UK school year, 2010/11, one third of children aged 10 to 11 were overweight or obese.

Like climate change, we know the problem is coming, but because the effects are at some point in the future, we are burying our heads in the sand, hoping the problem might just go away. For what is an easy situation to prevent: we need concerted action now. Jamie Oliver, once said "we're losing the war against obesity," We may have already lost it: 1 in 3 adults and 1 in 6 children are currently obese.

Just a spoonful of sugar, to help the obesity epidemic go down

Kamal Mahtani
Last edited 19th October 2011

Teaching on an Evidence Based Practice workshop recently I came across a truly jaw-dropping projection. A participant used a clinical scenario about obesity to bring up a paper about the US Obesity epidemic.The study is three years old now, but the authors use data on adults and children from the National Health and Nutrition Examination Study (NHANES), between the 1970s and 2004. The projections are frightening for the burden and health-care costs of obesity and overweight in the US if current trends continue. By 2048, all American adults would become overweight or obese. Depending on your ethnic background it could even be worse with the authors stating that Black women and Mexican-American men are likely to reach that state even earlier. However, the authors point out that they make a number of assumptions. Firstly they assume that the increase in obesity will be at its current rate. They also ignore the effect that all future policy, environmental and behavioural changes may have. Finally they ignore the possibility that some individuals may be genetically protected from becoming obese.

In the UK the predictions are not that much better. A recent four part series on obesity in The Lancet journal included a paper co-authored by Professor Klim McPherson of The University of Oxford. Their study stated that by 2030 there would be an additional 11 million more obese adults in the UK. This would have a knock on effect of an extra 6-8 million cases of diabetes, 5—7 million cases of heart disease and stroke and approximately 600,000 additional cases of cancer. This sort of news travels fast with The Daily Mail being one of the first to report these finding to the public.

So is it all doom and gloom? Not necessarily. In the same paper the authors go on to suggest that a 1% reduction in BMI (equivalent to a 1kg loss) across the entire population could avoid up to 2 million incident cases of diabetes, nearly 2 million new cardiovascular disease cases, and 73 000–127 000 cases of cancer. The authors further infer that this could be achieved through a reduction of 20kcal/day sustained over 3 years i.e. less about a teaspoon of sugar a day. Better still, if we were all able to give up 200 to 400 kcal/day, obesity levels would drop to 1990 prevalence levels.

So small changes may be the best way to start beating this epidemic. Something to think about before adding that spoon of sugar to your next tea or coffee.

Obesity: Inequalities in EBM, medical research and policy

Ami Banerjee
Last edited 26th August 2011

Today’s main news story is that obesity is on the up and will continue to rise if coordinated action is not taken at local, national and international levels. A Lancet series of articles examines the evidence for the growing burden and cost of obesity globally and the policy steps needed to prevent 65 million more adults in the USA and 11 million more adults in the UK becoming obese by 2030. Successive governments have allowed the food industry to self-regulate and the evidence clearly suggests that this does not work, since the industry’s interest are profits.

What strikes me is that instructive lessons learned from a strikingly similar case-in-point over the last 60 years, namely the tobacco industry, are not being put into practice. There was good medical evidence for smoking and its detrimental effects of health since the work of Richard Doll and Austin Bradford Hill showed the link with lung cancer in the early 1950s, but it was not until 2005 that the World Health Organization adopted the Framework Convention for Tobacco Control, the world’s first and only public health treaty. Our policymakers smugly talk about tobacco as a tackled problem, but it was less than 10 years ago that UK policy started moving in the direction of smoke-free public places.

We have an obese body of evidence (pun intended) to show that the pathophysiology and epidemiology of obesity is bad for our health, and we have enough evidence to show that current methods of tackling industry problems are not working. Governments are quick to say that the food industry is different but what are the incentives for the food industry to behave differently? Is it going to be acceptable to wait 50-60 years before governments and global health policymakers put evidence into practice? Evidence-based medicine aims, at the end of the day, to institute changes which make the health of individuals better. It seems that there are inequalities in the way evidence is put into practice, based not just on societal interests, but on conflicts of interest, particularly multi-billion dollar industries. If we are serious about EBM and evidence-based policy, we should take lessons learned from other sectors and apply them accordingly.

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