Something has gone horribly wrong in our relationship with food, the source of our physical energy. Until the 1970s the average human body weight had been remarkably constant over time suggesting the operation of a balanced biological system with effective appetite control mechanisms at work. But then everything changed rather suddenly producing the biggest epidemic the world has seen – the obesity epidemic. Thirty years ago less than one person out of ten people in income-rich countries was clinically obese (Body Mass Index 30+*). Today one in four people is clinically obese. In the US today 64% of people are classified as overweight or obese (BMI 25+) and it is estimated that, at current rates of increase, this will reach 75% by 2015. South Africa is not far behind with 50% of its population over 15 years considered to be overweight or obese. What is even more disturbing is the explosion of weight gain amongst children and adolescents. In South Africa 17% or nearly one out of every five children aged 1-8 is overweight. Studies indicate overweight children are highly likely to grow into overweight adults who are then at increased risk of heart disease, diabetes, hypertension, kidney disease, some forms of cancer and psychological problems. In fact, many obese children are starting to experience such problems, even before they reach adulthood.
What has happened that has relatively quickly added millions of kilograms to millions of people throughout the world? There are several possible explanations: food has become more readily available; average portion sizes and calorie contents have increased; more food is now eaten away from home; and we are exercising far less. But why are our appetite control mechanisms no longer effective and what is driving so many of us to eat much more food than our bodies need? Many people, including healthcare professionals, still believe weight gainers simply lack will power or perhaps have self-esteem problems. However, a small but growing number of scientists are starting to focus on other possible explanations for this ‘loss of control’ over eating. Several studies have shown that higher sugar, fat and salt levels in food lead to overeating. People do not overeat foods that are low in sugar, fat and salt. The same pattern is true in animals. Rats given balanced ‘rat chow’ eat what they need; rats given the sort of smorgasbord of junk food that we are exposed to on a daily basis overeat horribly and quickly become obese.
The triad of sugar, fat and salt are what make a food highly compelling. High amounts appear to stimulate the release of dopamine, a neurotransmitter which forms part of the brain’s reward system and underpins every behaviour pattern that is compulsive or addictive. Cocaine stimulates the release of dopamine, also known as the pleasure chemical, which gives us some idea of the compulsion of any activity that involves the dopamine pathway.
Many of us have what’s called a ‘bliss point’ at which we get the greatest pleasure from sugar, fat or salt. Combined in the right way, these three ingredients make a food product compulsive or what is being termed hyperpalatable. Food manufacturers, restaurants and fast-food outlets are responsible for the explosion of hyperpalatable irresistible foods. Sugar, fat and salt are either loaded into a core ingredient (such as meat, vegetables, potato or bread), layered on top of it, or both. The food industry designers refer to it as an ‘optimised fat pick-up system’ and many fast foods now have less meat than ever before, such as popcorn chicken and nuggets, and an increased percentage of fat pick-up. This keeps the food both cheap and compulsive.
When layers of complexity are built into food, the effect becomes more powerful and the rewards greater. Carbonating sweet drinks is one example of titillating a product to make it hyperpalatable. We tend to habituate to even these sorts of products if we eat or drink them on a very regular basis which means that the rewards and desires diminish. However, if the stimulus is sufficiently powerful, habituation may not occur, much in the way that it does not occur with cocaine use. This means the brain does not alter its dopamine response and desire remains elevated.
As David Kessler says in his book The End of Overeating: Taking Control Of Our Insatiable Appetite, “There’s still a lot we don’t know about the relationship between the dopamine-driven motivational system and our behaviour in the presence of rewarding foods. But we do know that foods high in sugar, fat and salt are altering the biological circuitry of our brains. Rewarding foods are rewiring our brains and we can no longer control our responses to highly palatable foods because our brains have been changed by the foods we eat”. The reward we get from these foods is so great it is overruling natural appetite control mechanisms, which previously ensured that we ate the amount of calories that we expended and maintained a stable weight
Much as there was a gradual societal shift in attitudes to smoking which changed individual behaviour, so there needs to be a shift in our attitudes to the type of food we are eating or overconsumption will become the norm and we will pay a high price in our health and quality of life, as all addicts do.