It’s a long time now since I was teased with the old nursery rhyme about what little boys are made of and, to be honest, I quite liked slugs and snails. On the other hand I couldn’t deny that sugar and sweet things, which were rationed then, were nice but in short supply. Since there was no television, we also ran around a lot, played football and climbed trees, so we avoided too much obesity.
When, aged 30, I went to the USA, the first thing that struck me was the relative obesity of so many of the students I taught. Over subsequent decades I have watched our young people catching up with their American contemporaries. Why have we as a population got so fat? We know that overweight is associated with increased risks of diabetes, heart disease, accidents and arthritis, even of dementia, and is thus a major cause of premature mortality and disability. It is therefore an important question.
Some facts can easily be ascertained as national and international statistics are available, and there is no doubt that the UK and Scottish populations are on average getting heavier in proportion to their height; it is pretty obvious that this isn’t simply greater muscle mass. In general, England fares slightly better than Scotland, and the Welsh are worse off than either. Obesity is defined as a Body Mass Index (weight in kilograms/height in meters squared) of more than 30. If you work out your own, be sure to square your height or you’ll get a nasty shock!
Some figures: in the USA obesity prevalence went from 15% of adults in 1978 to 35%. In the UK, the corresponding figures were from 7% to 25%. This contrasts with Finland (7% to 14%) and Japan (2% to 3%). First apparent in children in the 1970s, obesity had risen to 17% of five year olds and 25% of 11 year olds by the mid-2000s. Obesity also shows marked social and economic gradients. In poor countries generally the wealthier are fatter, as might be expected, but this is reversed in rich countries like ours.
In British five year olds, 6% of the least deprived are obese compared to 12% of the most deprived; corresponding figures for 10 year olds are 12% and 24%. Obesity persists throughout life, so that now we see much more obesity in the middle-aged, up to over 30% of those with no qualifications and 20% of those with degrees. Think of the figures of workers in Lowry’s paintings of the 1940s and 1950s in comparison with pictures of tattooed British workers on holiday on the Costa Brava today. There are also racial differences, obesity being more frequent in Afro-Caribbean and less frequent in Chinese British. From these observations it appears that the rise in obesity is likely to stem from changes in lifestyle, and we know that right from the time of conception diet is able to influence the expression of our genes, a so-called epigenetic effect. So even though obesity like many other physical characteristics obviously runs in families, let’s forget genes and look at lifestyle.
What changes have occurred over the last five decades? We have become less physically active and we eat much more. Unfortunately, it requires a lot of vigorous exercise to lose any weight and exercise gives you a greater appetite. If you go to a gym, try running on a treadmill or cycling for 30 minutes and read off the calories you have used up, then read on the bottle the calories in the drink that you felt the need for afterwards. So while it is true that more exercise is good for you in reducing risks of heart disease and dementia, it seems unlikely that it is the answer to the problem of obesity in a population.
The other dramatic change in lifestyle has been our food intake and particularly its composition, again a matter of national statistics. We all on average eat much more carbohydrate-containing food and drink, and less fruit and vegetable than we did 50 years ago. So we can plot a graph that shows a correlation between both total caloric intake and carbohydrate intake and changes in population body mass. This is called an ecological association and suggests that if we were to eat less in total or in carbohydrate, we would on average get thinner. It also suggests strongly that action to reduce obesity is likely to be more effective the earlier in life it is started and it may even be that a bad diet during pregnancy could begin to programme obesity in the unborn child.
Hard experience at an individual level suggests that dieting works for a while but then we gradually relapse. Dieting on a population level works in conditions of starvation but is not feasible in other circumstances. However, if we can identify the factors in the diet that bear the greatest level of responsibility there is a chance that a national intervention could work, if there is a convincing incentive. This has happened, for example, in Finland where a high fat diet was associated with very high death rates from heart disease and a public health campaign, inter alia, to reduce fat intake has had beneficial effects on mortality. This is about as close we can usually get to an experiment in this field of epidemiology; a trial of intervention. The proof of the pudding is in the eating.
Sugar has a chequered history. I recall as a child being taken on Sunday walks by my father to look at the rich people’s houses up the hill. ‘They got their money from the slave trade’, he used to say. I later learned that he was right, that the big old houses on Merseyside (and in London, Glasgow, Bristol and many other cities) were indeed built from the profits of slave labour (and widespread slave ownership – see ucl.ac.uk/lbs ) in the sugar plantations of the West Indies. It appears that the profits from recompense for losing slave ownership gave a huge boost to UK’s prosperity in the early 19th century.
Sugar at that time was essential for providing the quick, easily absorbed calories required to labour hard and long in the mills and mines. It still provides those easily absorbed calories and also, by stimulating appetite from insulin production, readily allows us to get hooked on it. And its incorporation into many foods attractive to children, sweets, chocolates, baked beans, biscuits and soft drinks makes it all too readily available and tempting. Herein lies the probable explanation of the social differences in obesity prevalence; it is easy to make foods and drinks sweet, so they are relatively cheap and also addictive, and the sugar industry takes full advantage of our susceptibility in order to maintain its profits. Few of us can resist a second and third chocolate out of a box. On the other hand, if you are aware of the problem, it is easy to avoid buying a box when you are shopping. Crucially, once children are programmed to obesity they are likely to remain obese throughout life or be condemned to permanent dieting.
There is now evidence that strict reduction of carbohydrates in diet leads to loss of fat and weight reduction. The easiest way to reduce carbohydrate intake is by cutting out sugar and things that contain refined sugar and this points to a public health measure that could make a big contribution to solving the obesity problem. So we can tell people, persuade the food and drink manufacturers, apply a targeted tax, or combine all three. Experience with the tobacco industry teaches us that telling people has only a small effect and persuading companies whose primary responsibility is to increase profits for their shareholders is little better. On the other hand, taxes and governmental regulation do reduce consumption. We have the example of tobacco; taxing and regulation work and improve health, and Scotland has led in this. Ultimately such action should also cut costs on the NHS, especially in treatment of diabetes and its many complications. Here is an opportunity for an enlightened government to benefit the population and also increase its revenue. What could possibly be wrong with that?
The most important message, until our governments take effective action, is to explain to parents and prospective parents the importance of limiting sweet things in their and their children’s diets. Look at the sugar/carbohydrate content of all processed foods and drinks when you buy them and keep the children’s hands off the sweets in the supermarket. There’s one good piece of news that I have kept back: for the first time since the war, over the past decade there has been a fall in childhood obesity among British children, from 25% to 20% in 11-15 year olds and from 17% to 12% in 2-10 year olds. Still far too much, but the message is slowly getting through and this is a trend to which we can all contribute.
By Anthony Seaton | September 2015