A report in the latest issue of The Lancet shows that Australia’s rate of obesity has risen the fifth fastest in the world since 1980. The global rate of obesity worldwide is twice what it was in 1980, and more than 65 per cent of the world’s population live in countries where being overweight kills more people than being underweight.
The weight of evidence indicates that the primary driver of the obesity epidemic has been eating too much, although sedentary behaviour is also part of the equation. Unsurprisingly then, the focus of much research has been on the source of these extraneous calories, with vigorous and ongoing debate over whether fats or carbohydrates (especially refined sugar) are the main culprits.
Fats and sugar contribute, of course, but focusing on a single culprit misses a fundamental point. The obesity problem is best understood not as the result of eating too much of a single nutrient, but because of the way highly processed foods have skewed the proportions of nutrients in our diets. Our diet is out of balance with our physiology, and the consequences are dire. We are losing the language of food and delegating our nutrition to the processed food industries, whose primary motivation is not our better health.
In particular, the dwindling ratio of protein to carbohydrates and fats in processed foods is of real concern, effectively driving us to overeat as our bodies scramble to get the amount of protein we need.
Research at the University of Sydney’s Charles Perkins Centre has shown that humans, like other animals, have evolved to possess an in-built appetite system to control the consumption of proteins, carbohydrates and fats, as well as micro nutrients like calcium and sodium. These systems compel us to eat a balanced diet – a lack of one nutrient will signal “eat more”, while an excess of another will signal ”eat less”.
Unfortunately, these basic biological signals are being circumvented because we now live in a foodscape barely recognisable to our ancestors. The range of processed food becoming available is evolving faster than our appetite control systems. Simple sugars and fat were a rare luxury in our evolutionary past, which may be why humans tend to favour the fatty and sugary foods that now surround us.
Pure economics is also part of the reason we are diluting protein in our diets with more carbohydrates and fats. Food manufacturers have a financial incentive to replace protein with cheaper forms of calories.
Worse still, processed foods such as savoury snacks are manufactured to make our bodies think we’re eating protein-rich foods, despite the fact they are loaded with fat and carbohydrates. When we need protein we crave savoury and salty flavours, since in nature these are cues for high-protein foods. Coupling such flavours with deep-fried starch, as in potato chips, creates a protein decoy, luring us to eat yet more fat and carbs but leaving us still seeking protein.
In the agricultural sector, the emphasis has long been placed on producing more food. Yet malnutrition among children in developing countries is not significantly diminishing, despite increases in production. We need to rebuild the human food chain to ensure nutritional quality and well as quantity.
Our built environment is also a major factor in the obesity epidemic, having been designed for convenience instead of positive health outcomes. Among other issues, a lack of viable public transport and active transport options, increased fast food availability, social isolation and a shortage of public spaces all play a part.
Our work structure means most of us spend most of our day sitting still, with prolonged sitting now emerging as a major health concern around the world. Obese Australian women average just one hour of vigorous exercise a year, while obese men average less than four hours.
It is clear that we need to take a multifaceted approach if we are to overcome the obesity epidemic. The University of Sydney has launched its world-leading Charles Perkins Centre hub, a $385 million research and education facility which aims to find integrated, real-world solutions to obesity, diabetes, cardiovascular disease and related conditions.
Instead of looking for a silver bullet solution, the centre looks for solutions at the junctions between disciplines – clinicians, nutritionists and health scientists work with philosophers, educators, marketers, agriculturalists, architects, economists and many others.
We need to move fast. If we don’t change the course of our nation, a shuddering 80 per cent of all Australians will be obese or overweight in a decade, while diabetes is set to become the major cause of morbidity and mortality in Australia by 2016.
Professor Stephen Simpson is Academic Director of the Charles Perkins Centre at the University of Sydney, which opened on Thursday.
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