Zombies, exams and childhood obesity

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I, like most paediatricians you will ever encounter, have a truly comprehensive plan of action in the event of a zombie apocalypse. Bear with me.

Doctors have to do a lot of exams. By my rough estimation I’d say that they are required to do approximately all of the exams in the world, ever. Give or take one or two. This makes my colleagues and I experts, if in nothing else, on the practice of these, aforementioned, exams. Now, given the extent of my rather portentous knowledge in this area, I am willing to share with you, lucky reader, three absolute truths regarding exams: if the word ‘never’ or ‘always’ is in a true/false question, the answer is universally ‘false’; to be honest it is never, ever, likely to be option C; and finally, (make no mistake, this is by far and away the most important thing I have ever gleaned from years of studious efforts) following an examination people generally divide into two groups: sadists and ostriches.

The ostrich is a pleasure to be around. Having had information forcibly extricated from the dull grey matter sloshing around between his temporal bones he will calmly and charmingly proceed to forcibly stick his head into the proverbial sand and, much like a politician enjoying his university years, resolve never to speak of it again. I am an ostrich. All the very best people are ostriches in my humble opinion.

Sadly, there remains the sadist. These despicable individuals are to be avoided. Your ongoing pain is their raison d’être. They will insist on dissecting every single question, and, indeed, your ongoing will to live. They will alert you to the fact that you confidently answered that you would prescribe a drug that would, in fact, have caused the patient to stop breathing embarrassingly quickly and mistook a life-threatening rash for simple eczema. They will cause you to doubt whether you really can tell the difference between a blood gas result showing a hypochloraemic hypokalaemic alkalosis and your nan’s shopping list. Awful folk.

By the way, as is no doubt clear by now, this is a blog post about the childhood obesity epidemic.

After one particularly brutal exam (imagine the end physical result of having called the boxer, Floyd Mayweather, a ‘really rather tiresome fellow’, directly to his face*) I pushed through those people whom I knew to be sadists and sought out the company of a good, ostrich, friend. Our Royal College, in an effort to maximise our examination performance and enjoyment, had asked that we drive a couple of hours down the road in order to sit our little test. This then necessitated a long car journey back home, wherein we two ostriches would need to do all that we could to avoid speaking of the mental torment we had just been through. And t’was thus that Rachel and I developed a very, very detailed plan regarding how exactly we would proceed should our nearest and dearest start to expire into flesh-eating monsters. Let me just say this: the babies on the neonatal unit who were under our care at that time would have almost certainly have survived to found our new society.

I’m pretty sure most paediatricians, with the exception of the sadists (who, let’s face it, we could all do without come the end times) will have been through exactly the same thing and thereby ended up having exactly the same conversation.

Which leads me to segue (quite naturally, I think you’ll agree) to the British Library. You see, in my spare mental moments I’ve often continued planning for the impending apocalypse. And it is clear to me that I don’t know anywhere near enough about anything. Sure, I could take a pop at intubating you and know what antibiotics to give my surviving friends, but I certainly don’t know how to fly a helicopter away from an approaching ravenous horde of walking dead, or, probably more crucially; how to farm. Fortunately, for my plans at least, the British Library is a legal deposit library: this means that every book ever published in the UK is required, by law, to be stored there. So, fellow future survivors, let us be clear: somewhere just outside of Boston Spa lies an enormous repository of almost all human knowledge (there isn’t enough space to house it in London). Bingo. We just need to make it there once all the fuss has died down. But, when we get there, how on earth will we know where to start?

Our genomes, housed inside the nuclei of all of our cells, contain vastly more information than any legal deposit library. Your genome stores reams and reams of information, a great deal of which is just ‘junk DNA’, left-over from our evolutionary ancestor’s past lives and of no use to us – this is non-coding DNA. It’s not being used. It is the biological equivalent of the instruction booklet sitting in your kitchen drawer, for the appliance you no longer own. What remains is the DNA our cells utilise to build the proteins that make you, you. But it turns out that, just like post-apocalyptic me, our cells are required to make decisions about what information is likely to be important and useful for their survival. This, rather simplistically, is ‘epigenetics’, and this, rather importantly, changes what we think we know about obesity in children.

In 2014, a team from the University of Cambridge published a study in the journal Science that looked at what happened to the offspring of mice who had been starved during the latter part of their pregnancy. Interestingly, the offspring of these starved mice were more likely to gain weight and develop diabetes than the offspring of mice who had not been starved. When they compared the genomes of these two groups of offspring they found significant differences in the ‘methylation’ of various regions of DNA (methylation is one chemical process that acts to effectively silence or ‘switch off’ genes). It seems that the cells of mice born to starved parents were potentially being geared up to survive in harsh conditions, leaving them with a propensity to gain weight and develop diabetes despite later being fed a normal diet. In the age-old philosophical battle of nature vs. nurture, it transpires that nurture can significantly alter nature.

This finding is borne out by observational findings seen in human populations. The children of a Second World War Dutch population who had faced appalling starvation during the winter of 1944-45 were born underweight, as you might expect. But as they aged they were found to have an abnormally high chance of developing obesity and diabetes. It’s as though in the womb they were primed for tough times ahead.

At this point you’d be quite right to point out that most obese children don’t have significantly underweight mothers; and you’d be right. But, interestingly, further studies have found that being overweight or eating a poor diet can influence your offspring’s epigenetics. Take a German study published in Nature Genetics this year that looked at the progeny of mice who had been fed a high-fat diet. Their offspring were much more likely to gain weight on a normal diet, i.e. a diet that normal mice would eat and not gain weight on. Most worryingly, this effect persisted in subsequent generations, even when the next generation of mice ate a normal, healthy, diet.

And it’s not just diet. Some more contentious studies have implicated day-to-day environmental chemicals, such as those used in common plastics, in epigenetic changes.

This might all sound like pseudoscience were it not for the fact that, this year, the World Health Organisation report from the Commission on Ending Childhood Obesity listed epigenetics as a significant contributing factor in the development of childhood obesity. And it made it clear that this isn’t just a Western disease. In terms of pure numbers, the developing world has far more obese children than developed nations.

Why do I care about this, as a paediatrician? Well, firstly, obese children go on to become obese adults. Furthermore, obesity in childhood can lead to significant health problems: more and more children present with type-2 diabetes each year. But, and this is crucial, it most concerns me because the children I care for are powerless to do anything about the environment they were born into or their parents’ circumstances at birth. The potential role of epigenetics means that lifestyle advice alone won’t cut it. Exercise and diet might not be quite as effective as we’ve maintained. This isn’t just a problem for the medical profession. This requires a wholesale rethink about how we can change our obesogenic environment of sedentary lifestyles and plentiful energy dense foods into one that protects future generations. This is a public health crisis orders of magnitude greater than anything we’ve ever faced before.

Rachel and I have a plan in case of zombie apocalypse. I’m not sure we’ve got a plan for this yet.
*NB: Dear Floyd, I just want to clarify that I don’t actually think this.

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