Fat, Fate, and Disease : Why we are losing the war against obesity and chronic disease (4 page)

If battling infectious disease is complicated, battling diabetes and cardiovascular disease is proving to be even more complex. Until recently it was hoped that discoveries of genetic differences would explain the variation in disease risk which we find between individuals. However, while variation in our genes accounts for some of our differences in risk, it is not as much as we had previously hoped, or as advocates of genetic medicine had prophesied. Not only is the effect of our genes on our risks of obesity, diabetes, and cardiovascular disease small, but it does not easily explain the patterns of obesity and non-communicable disease that we observe around the world.

Besides, if the problem lay solely in our genes we would have little capacity beyond the implausible use of gene therapy to change our fate. This would be a depressing scenario. But fortunately there is much more to health and disease than our genes. Nonetheless, if individual variation in the settings of our appetites and our metabolic controls can be explained at least in part by genetic variation, we might, through genetic research, get some clues to the complex processes by which diabetes and cardiovascular disease develop. And indeed such science is finding new and exciting explanations that do offer hope for intervention.

We now recognize that even some children and young people who are not obviously fat may already be on a path to diabetes and
cardiovascular disease later in their lives, and that it is not easy to switch them to a healthier path. In the last two decades there has been an explosion of knowledge which shows that what happens even before we are born can put us on the path to obesity and risk of non-communicable disease.

We will explain in the second half of this book that there are several developmental paths to obesity and to diabetes and cardiovascular disease, and that obesity and disease risk are starting to appear in childhood more and more. A woman who is obese may have children who are more likely to become obese; the incidence of diabetes in pregnancy is rising, and the effects of this on the fetus can lead to a higher risk of obesity and diabetes in the next generation. Babies who are born prematurely or small are at greater risk; twins, which are increasingly common in a world where women have their babies later and where the need for techniques such as in-vitro fertilization is becoming common, are at greater risk. And fathers may have something to do with it as well. There is much to think about here.

Perhaps from this list we can begin to see how important it is to understand the fundamental biology of how risk is set up during our individual development as fetus and infant. We do not leave this part of our lives behind when we are born or when we are weaned. We carry all this biological history, unremembered, around with us for the rest of our lives. No wonder that we all differ as adults in our risk of obesity and in our responses—or lack of responses—to simple interventions such as dieting or exercise. No wonder that this leads to differences in our risk of diabetes and cardiovascular disease.

It used to be thought that most of these developmental risks could be captured in the measurement of birth weight, because this seemed to indicate how well the mother’s womb had provided the resources needed for the baby to grow to his or her genetic potential. As research has progressed, however, we find that many much more subtle influences on fetal development, which are not reflected in
changes in birth weight, also affect later disease patterns. Many of these influences reflect the mother’s nutrition or health, often even before she became pregnant. Sometimes they even depend on the health of
her
mother. They may be affected by the health and lifestyle of the father too. We will explore this very important new research in this book because it leads us to the conclusion that a very high percentage of us have echoes of developmental factors in our bodies which play a major role in our later risk of ill health.

These developmental influences may appear subtle, but they are also commonplace. One somewhat surprising but important example is that recent research shows that first-born children are at greater risk of developing obesity than subsequent children of the same woman. Think of the questions which this observation, which is statistically robust, raises. Should women have different diets before or during their first pregnancy? Should we treat first-born children differently to reduce their risk? What are the socio-economic implications of this in urban China, where legislation has restricted family size to one child?

Such descriptive observations are all very well but they may not actually be very helpful if we do not know the underlying biology—in other words, what is cause and what is effect. Increasingly, however, we are gaining insights into how such effects work, and we realize that they are part of fundamental biological processes which many other species use in their development too. Those who work in this field are convinced that here lies an important missing link in the problem of variation between people in risk of obesity, diabetes, and cardiovascular disease. This new knowledge may help us to mount an effective set of strategies to address the problem.

There is a large body of scientific evidence for these ideas, yet somehow we feel that we are being controversial in voicing them.
The developmental perspective on diabetes and cardiovascular disease appears to go against the grain of current wisdom in this area. We can see this from a very recent example. In October 2010 the Organisation for Economic Co-operation and Development, the intergovernmental think tank of advanced nations on economic issues, produced a report on obesity. It runs to many pages, and was the culmination of years of work. Yet despite its apparent sophistication, it failed to mention development once, despite the overwhelming scientific evidence for its importance. Nor did it discuss the problems of inadequate or excessive weight gain, obesity, or diabetes in pregnancy. Although we single this report out for example, it is typical of a body of work and a tradition in public health. The blinkers seem to fit very comfortably, it seems. Why?

The practicalities of modern science and policy formation provide an explanation in part. The methods for studying risk factors in populations of adults are often limited by allowing us to look only at current factors such as smoking, diet, and exercise. They do not let us look backwards from adulthood into early life readily, if at all. The research needed to do this takes many years and is expensive. It is perhaps not surprising that it has taken time for a sufficient body of knowledge to be built up to demonstrate the importance of early development. But now that we have such knowledge, there is no excuse for ignoring its implications any longer.

There are vested interests as well as these down-to-earth practicalities which have hindered progress here too. Some drug companies would much rather focus on treating disease than preventing it, especially if prevention has to start in childhood when drug therapy is undesirable. Much of the food industry focuses on the profits to be made from fast foods and energy-dense fatty and sweet foods and drinks. Politicians and the electorate would, understandably, rather focus on the here and now than see their tax revenue directed towards interventions to prevent disease likely to occur more than ten years later.

Unfortunately, if we ignore the developmental perspective, we may miss the biggest opportunity for effective intervention. Indeed, a recent UK government think tank, the Obesity Taskforce of the Foresight Group, identified development in early life as the only time when effective strategies to deal with the problem of obesity are likely to be successful. And we have some pretty good ideas of strategies—some practical, some still on the horizon—which give us hope.

But to get to the point of actually implementing these strategies means thinking beyond our biases and taking our blinkers off.

And here we meet other cultural and social factors in operation. In Western countries those of lowest socio-economic status are most at risk. Is this simply because poorer people buy cheaper food, which is often of lower nutritional quality, or are there more complex factors operating? We will have to discuss this in this book. Moreover, there are big cultural differences in how people perceive their body shapes. So, when we try to reduce obesity in a population, are we addressing concepts of body shape or the wish to prevent disease? Certainly, for most people in developed countries it is the former—after all, the diet industry is built upon images of glamour and sexuality, not on preventing disease. We need to consider the implications of this too.

We wrote this book with two goals in mind. First, we wanted to show that the problem of obesity and the all too common non-communicable diseases actually looks different if we take off our blinkers—suddenly we see that we need to do more than talk about diet and exercise, bemoaning the shortcomings of people for whom these do not work. And we see that new scientific discoveries about human development give new insights into why the incidence of diabetes and cardiovascular disease is increasing, and novel ways of detecting early in their lives the people who will be most at risk later.

Our second goal is to lay down a challenge—especially to governments, to NGOs, and to many agencies—to think outside the box, to take a more holistic view which extends beyond entrenched biases.
They need to consider the enormous social and cultural variations that limit personal motivations. They need to understand that the issue is not simply about choosing to be slothful and gluttonous. They need to understand that a healthy world starts with healthy parents, which leads to healthy fetuses, healthy infants, healthy children, healthy adolescents, and then to healthy adults.

We will argue that until such a life-course perspective, along with a deeper understanding of why people live their lives in the ways that they do, has been incorporated into policy we will not change substantially the fate of many of us around the world. We will be destined to get fatter and more of us will suffer from disease.

If we live in a developed country where the average income is high, it is impossible to ignore the collective and entirely justifiable hysteria about fat. There is story after story about how our population is getting more obese. And this does not apply just to adults, for children and even infants are becoming obese too. Governments are being urged to tackle the problem, to give it a much greater priority, because the human cost of obesity is enormous.

Take a walk on the Bund in Shanghai or in the Zócalo in Mexico City. You come across well-dressed young children being walked to a museum by their teachers. The children are lively, animated, and excited, but one thing stands out—they look increasingly like children in London or Chicago or Sydney—many of them are plump. Sit in a cafe in a provincial town such as Arequipa in Peru, or in Udaipur in India, and again you will see many young adults who look on the fat side. Does this really matter? Isn’t it just a matter of
aesthetics? We live in today’s world, and today humans tend to be fat. Shouldn’t we just stop worrying about it?

No.

Excess fat, depending where it is in the body, is a major risk factor for disease. The lifespan of someone who is obese (with a body mass index or BMI of 40–45) is eight to ten years shorter than that of someone who is not. The effects are graded, getting worse as fat builds up in our bodies. Someone of average height who is overweight will increase their risk of death by about 30 per cent for every 15 kg of excess weight they carry. The chances of disability—from whatever cause—are twice as great in people who are obese as in those who are not.

Adult onset diabetes, heart disease, high blood pressure, and stroke are all much more likely if we are obese. The same is true of joint disease, kidney and reproductive problems, and even some mental illnesses. Most people in the world will die from one of these non-communicable diseases, and because their detrimental effects start well before death occurs, their impact on both an individual’s life and their ability to contribute to society is enormous. The cost to the health sector and to the broader economy of a nation is almost immeasurable. Most attempts to put a price on the problem are horrifying, but are almost certainly underestimations. The World Economic Forum recently calculated that non-communicable disease will cost the world more than US$50 trillion over the next ten years.

These diseases are now as much of a problem in the developing world as in the developed world. And as people in the developing world live longer when other aspects of their lives improve, the rate will rise even more. And there is now evidence that being obese is a risk factor for some cancers of the breast, colon, and perhaps the uterus, oesophagus, and kidney. It has been calculated that 25 per cent of premature deaths of women over the age of 50 in the United States would be prevented every year if they were not so fat.

But we have to be careful about how we interpret such figures. Obesity on a global scale itself was rarely a health problem in its own right until recently. We see television stories about 300-pound people suffering from morbid obesity who cannot move from their homes, who cannot breathe properly, and whose skeletons cannot support their weight. These are real problems and often there is an underlying medical explanation for this extreme obesity. But increasingly, we also tend to stigmatize fat people and people with relatively lower degrees of obesity. This does not help, of course, for it can affect their mental health and, paradoxically, increase their obesity.

But morbid obesity is not the prime focus of this book. In relation to the magnitude of the chronic disease problem, it is still small. We will focus on the issues of diabetes and cardiovascular disease and their relationship to much lower degrees of obesity. Too many people in every country on the planet are being affected, or will be affected, by these diseases. What is worrying is that these diseases are striking at much younger ages. Thirty years ago a child with type 2 diabetes was a medical rarity—now in Western countries more than half the children attending a diabetes clinic suffer from type 2 diabetes.