Free Fat, Fate, and Disease : Why we are losing the war against obesity and chronic disease by Mark Hanson Peter Gluckman

produced a big change, it was small compared to the changes in our diets over the past 200 years. The industrial revolution brought with it an agricultural revolution, which gave us a greater dependence on large-scale farming of grain, corn, sugar cane, and beet. The industrial revolution also saw the dawn of the modern food-processing industry. Food changed from being composed of simple natural ingredients to increasingly processed and refined products. Salt, sugar, and fats were added to improve taste and preserve the food. The food industry grew as cities expanded, so that fewer and fewer people across the planet could grow their own food. The relationship between food as it was sold and its original ingredients became more remote. In the 1860s,Emperor Louis Napoleon III of France offered a prize for the development of a substitute for butter suitable for use by the armed forces and the lower social classes (don’t ask what went into the winning recipe), and since then synthetic spreads and cooking oils have become a common part of our diet. For many years some processed foods have contained trans-fats, which were a direct result of the processing of the ingredients. Corn oil and corn starch became nearly universal ingredients, and so fructose and omega-6 fatty acid levels in foods started to rise.
    Then along came the fast food industry, the soft drink industry, our expanded intake of confectionary and alcohol—all excess calories that are easier to turn into fat than energy. And the cheapest foods now are often those that are most calorie-dense—so the more impoverished people in our societies eat less balanced diets than those who are better off.
    Technology has changed our lives in other ways too, of course. Few of us now hunt or fish to feed ourselves or wander the forests in search of tubers and seeds. Fewer and fewer of us even walk to a shop to buy our food—we are more likely to drive or to take a bus or train, or just to pick up the phone or order online. Manual work is increasingly replaced by machines. Leisure is spent in front of a computer or television, rather than walking or playing a game or a sport outside. Our children are more likely to be driven to school than to walk or ride a bike.
    Of course we do not know how much energy our hunter-gatherer ancestors expended each day—some anthropologists think that it was much more than we do now; others are less certain. The estimates are based on hunter-gatherer communities which still exist, but they have changed their lifestyles over the last 10,000 years too, and many of them are not free of modern influences. But if we look at more recent times, the situation is clearer. Most of us expend much less energy in living our lives than our great-grandparents did a century ago. Studies in countries such as Japanshow a direct correlation between the number of motor cars and the number of people who are obese. Other studies find the same correlations with the average number of hours spent watching television. While it is tempting to draw a cause and effect relationship, there is considerable debate about this. Would increasing exercise at a population level reduce the rate of obesity? Logic suggests that it would, although the size of the effect may be much smaller than might be expected—for reasons which will become apparent.
    We have grown up eating three meals every day with one or two snacks in between them. It was somewhat different in Victorian times, as many people had large meals at breakfast and in the evening but little for lunch. But as we now live and work in heated buildings and need to metabolize very little to keep warm, and as many of us spend our working days and leisure time sitting and being transported about the world by mechanical means, we can see how easily a mismatch between what we eat and how we burn it up can occur.
Active kids
    Many parents bemoan the fact that children just do not seem to engage in as much physical activity at