Dr Sarah McMullen gives her views on childhood obesity

MUCH attention has been given to the issue of childhood obesity, but what does being overweight as a youngster mean for your wellbeing in later life?

Dr Sarah McMullen

MORE and more children are becoming obese, and the impact of this on their future health is a huge concern.

We know that being obese as an adult is a bad thing – you are much more likely to develop diabetes, high blood pressure, heart disease and cancer if you are overweight or obese as an adult.

The World Health Organisation has estimated that around a third of coronary heart disease and stroke cases are due to excess body weight.

What about children? Well, they are also at much greater risk too.

Type II diabetes used to be considered an adult-onset disease, but it is appearing in younger and younger children. Early signs of heart disease are also more common in children who are obese.

It is commonly stated in the media that the current generation of children will be the first to be outlived by their parents. Is this really true?

So what can new research possibly tell us?

We know that obesity is a bad thing, and we know what we need to do about it – get people to eat less and exercise more.

Unfortunately it is not that easy. We live in an environment with a plentiful supply of foods high in sugar and fat, which are very appealing to our tastebuds, and where most of us are not required to do much exercise as part of our daily routine.

Almost everything about the environment we live in pushes us towards eating too much in the way of high energy and unhealthy foods, and drives us towards piling on the pounds.

Some of us are more able to resist this temptation than others, and we’re only just starting to understand why this is the case.

I get very frustrated when I hear people (particularly politicians) saying that individuals should take full responsibility for their own health and just eat less. If it was that easy, we wouldn’t be seeing nearly half of our population becoming overweight or obese.

As a Nutritional Scientist, my job involves conducting research into how diet and obesity impacts on health and what we should be doing about it.

We do this by studying groups of people, and by using laboratory experiments to understand what happens in the body when we eat different diets.

I need to keep up-to-date with the huge amount of evidence available from studies worldwide, so I also spend a lot of time reading and reviewing scientific papers. Sometimes there isn’t clear evidence and reaching a conclusion about whether something is good or bad can be very difficult.

Together with my colleagues, Louise Lloyd (a nutrition graduate from the University of Nottingham) and Professor Simon Langley-Evans (a professor in human nutrition at the University of Nottingham), I was interested to know what the long-term effects of obesity during childhood are.

We know that having too much body fat has negative effects on our health, but how far into the future do the effects last?

If you are overweight as a child but lose weight to become an adult with a healthy body mass index, do the effects of your childhood obesity disappear, or are there permanent effects on your adult health which you can’t reverse?

We collected all of the evidence which has been published on the effect of childhood obesity on long-term adult disease, to try to find a balanced answer to these questions.

The evidence included tens of thousands of studies of people leaving in Westernised countries, and our unbiased, systematic reviews were published in the International Journal of Obesity.

Our analysis of the research as a whole goes against many of the conclusions from the individual studies, showing how important it is to look at the evidence as a whole.

The good news is that our research suggests that the long-term effects can be reversed.

The research showed that those who are overweight as children, but of healthy weight as adults, are at no greater risk than people who have been at a healthy weight throughout childhood and adulthood.

So this strengthens the argument for tackling obesity during childhood, as it suggests that this will remove any risk of lasting harm.

There was something even more fascinating in the data, though. It seems as if people who are a relatively thin during childhood and then overweight as adults are at greatest risk of high blood pressure, type-2 diabetes and heart disease.

This was an unexpected finding, as we tend to assume that those who are at greatest risk are those who’ve been overweight for the longest time.

Quite rightly, a lot of focus has been placed on tackling childhood obesity. However, those who are thin as children are at an even greater risk if they go on to become obese adults.

This is a very important finding, as our results suggest that the work of nutritionists and dietitians might be missing an important at-risk group.

Unexpectedly the work suggests that there could even be a slight protective effect if we are overweight as children and reduce our body mass index in adulthood.

There is a dangerous message here. Should we be suggesting that the best approach is to be overweight as a child, then to lose the excess fat to become a healthy weight adult?

I will answer this with a resounding no! Children who are overweight are much more likely to be obese as adults, and are developing food preferences and behaviours which will affect how well they can control their diet in adult life.

So this strategy is far too risky, as we are seeing all over the developed world at the moment – obese children becoming obese adults and developing obesity related diseases.

We also don’t have an explanation for this surprising finding, and this is something we will be working hard on over the coming years.

So what message comes out of this new research? The key message is still the same – the consequences to our health of being obese are huge and we need to tackle the levels of obesity in the whole population. However, children are particularly vulnerable to becoming overweight, as they actually have quite little control over the foods available to them.

They also haven’t yet developed the capacity to make rational decisions based on the long term consequences of their actions.

We really do all need to take responsibility for the health of future generations, and this is a shared responsibility. It needs the support and involvement of parents and carers, the food industry, and the education and social support systems, local and central government. So think about the role you can play, and take part.

Dr Sarah McMullen, who is originally from Durham, is a lecturer and researcher in human nutrition in the Division of Nutritional Sciences at the University of Nottingham.

FOR MORE INFORMATION

To find out if your child is a healthy weight, see your GP.

They will check your child’s weight and height.

Your GP may also ask about how much activity your child does and their eating habits, any family history of weight problems. Check the Food and Diet section on the NHS Choices website for more information.

This research was funded by the Organix Foundation (charity number 1127780), a grant-giving body that funds research projects that focus on the links between food quality and children’s health. The research was published as two systematic reviews in the International Journal of Obesity.

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