Two very different but valuable crops are grown in Central and South America. After hours of toil, each is carefully harvested. But it's not the plant itself that is prized: it's the product inside. So both crops are subject to a process of extraction. The aim is to have a high concentration of pure product. One of the crops is sugar cane and the other is the coca plant, which contains cocaine alkaloid.
Consuming either sugar or cocaine stimulates the brain’s pleasure centres. When they are purified, this effect is heightened, producing an exaggerated biological response. For example, coca leaf has been chewed in Central and South America for hundreds of years. It's used as a local anaesthetic, to increase stamina and to fight fatigue. It contains the neurotransmitter precursors tryptophan and tyrosine and essential minerals. In short, coca leaf chewing is not a problem but a socially advantageous adaption. However, once it’s processed down to pure cocaine it becomes notoriously addictive. This is thanks to the rate at which cocaine enters the bloodstream, which triggers the brain’s reward system in a way that the slower-acting, diluted cocaine in the coca leaf does not.
Researchers at the University of Michigan and New York Obesity Research Centre think the same thing is happening when we eat food processed to yield artificially high concentrations of sugar and fat. For example, in rats, the development of obesity and overconsumption of 'hyper-palatable' foods was found to cause changes in the brain similar to those created by drug addiction. Dopamine is released, which is the brain's way of teaching you that whatever you just did is good, and you should do it again.
This reward system taught us behaviour that improved our chances of survival and reproduction. But now that the foods we have available are so energy-rich, this system has become pathological. Foods laced with high levels of sugar and fat hijack the feeling of pleasure that was designed for foods with far less sugar and fat. And too much dopamine leads the brain to adapt to it – which means you need even more to create the same level of pleasure.
One of the researchers who argues that certain foods can be addictive is Ashley Gearhardt. She completed her PhD in psychology at Yale and formulated and validated the Yale Food Addiction Scale against the DSM5 criteria of addiction. Now an assistant professor at the University of Michigan, she recruited 128 students for a study of food addiction and a further 398 for a community questionnaire. She found that a higher score of food addiction was strongly associated with an increase in body mass index. The most 'addictive' snacks were – and this may not come as a huge shock to you – pizza, chocolate and chips. The least addictive were cucumber, carrots and beans (no sauce).
But the theory of food addiction is still controversial. Critics say we can't be addicted to something that is necessary for our survival and which we cannot avoid. Gearhardt agrees that not all foods trigger addictive eating – but some highly processed foods do, and indeed share characteristics with drugs of abuse. For example, cocaine and chocolate come in high doses and are absorbed rapidly.
Regardless of whether you buy into the concept of food addiction, the results of eating unhealthy, high-energy foods are self-evident. A quarter of adults in England are obese. Admissions to hospital with a primary diagnosis of obesity increased nine-fold between 2003 and 2013. That's an astonishing statistic. Obesity is reckoned to cost our economy £47 billion a year. But while selling cocaine is illegal, selling sugar and fat is fine, apparently.
I don't think it is fine. And now I'm going to make a suggestion that the libertarians among you will really hate. We cannot outlaw sugar and fat in the same way as cocaine, but the food and drink industry needs to be treated with the same heavy hand as the tobacco industry.
It is time the Government took radical action. At the moment, the only public health initiative involving the food and drink industry is the Department of Health's Responsibility Deal, a voluntary scheme that asks companies to sign up to pledges 'to support healthy choices'. According to a recent report in the British Medical Journal, this initiative has failed to meet its target of reducing the nation’s calorie consumption by five per cent. Actually, 'failed' is putting it mildly. Total calories purchased per household were nearly 12 per cent higher in 2014 than in 2006. Meanwhile, companies have failed to keep their promise to reform advertising and product placement.
As I say, we need radical action. Forget a sugar tax – that doesn't go nearly far enough and would simply put an added economic burden on the poor without necessarily changing behaviour. High taxes on tobacco have added to falling smoking rates, but it remains a habit that disproportionately affects those on a low income. (In 2009, only 14 per cent of 'managerial and professional households' smoked, compared with 33 per cent of households with 'manual and routine' occupations.) What we need is a blanket ban on advertising processed food and drink, plus tax cuts for 'ethical' food companies that don't add sugar or fat to their products.
But even this isn't enough – not if we're serious about halting the public health disaster happening right in front of us. So let's consider using an American model, with a few important tweaks. The food stamps programme, now called the Supplemental Nutrition Assistance Program (SNAP), provides low-income households with money exchangeable for food. But what it doesn't do is set nutritional standards. This is a missed opportunity. People on the SNAP programme eat slightly more fruit than the average American, but their overall score on the healthy eating index is lower.
This should be a lesson for the UK. Setting aside a portion of monthly welfare payments that can only be spent on non-processed food would improve people's eating behaviour (and reduce their risk of being rushed into A&E with a heart attack). This money needn't cover the whole of someone's food expenditure, but it would ensure that a core amount goes towards foods that promote a balanced diet. This would also have a knock-on effect on industry. In the US, companies such as Coke and Pepsi receive a significant portion of their revenue through the SNAP program. If processed foods were out of bounds, this would put real pressure on manufacturers to produce food and drink that, put simply, is safe to consume.
Highly processed foods, with all the nutritional value stripped out and sugar and fat thrown in, should be treated in the same way as alcohol or tobacco. They are ruining our health and draining the NHS. In suggesting this I'll be accused of wanting to extend the reach of the nanny state. But the alternative is to sit back and watch people eat themselves to death.